%+t
ROOTSIMU V4.0
A dynamic 
simulation of 
root growth,
water uptake, and 
biomass partitioning
in a soil-plant-atmosphere 
continuum:
update and documentation
June 1986 Agronomy and Soils Departmental Series No. 109
Alabama Agricultural Experiment Station Auburn University
David H. Teem, Acting Director Auburn University, Alabama
I , . II - - I

TABLE OF CONTENTS
Page
LIST OF TABLES................................................................... 4
LIST OF FIGURES.............................................................................. 4
INTERPRETIVE SUMMARY.................................. ...................................... 4
INTRODUCTION ................................................................................ 5
MODEL DESCRIPTION ................................................................. 5
MODEL MODIFICATIONS...................................................................... 6
Weather Data .................................................................... 7
Carbon Balance.................................................................. 8
Water Balance.................................................................... 8
MODEL INITIATION........................................................................... 8
Weather Data ................................................................... 8
Plant Material................................................................... 9
Soil Conditions.................................................................. 12
MODEL RESTRICTIONS ........................................................................ 12
MODEL PREDICTIONS......................................................................... 12
Environmental Conditions......................................................... 12
Plant Growth ................................................................... 13
SIMULATION INSTRUCTIONS.................................................................... 16
Mainframe or Mini-Computer...................................................... 16
Micro-Computer................................................................. 16
DISCUSSION ................................................................................. 18
CONCLUSIONS ................................................................................ 20
BIBLIOGRAPHY ............................................................................... 21
APPENDIX A, CSMP-LiSTING OF SIMULATION MODEL.................................... ..... 23
APPENDIX B, FORTRAN-LISTING OF SIMULATION MODEL...................................... 45
APPENDIX C, ACSL-LiSTING OF SIMULATION MODEL (VERSION 1.5)......................... 63
APPENDIX D. GLOSSARY OF TERMS USED IN SIMULATION MODEL............................... 75
FIRST PRINTING 950, JUNE 1986
Information contained herein is available to all persons without
regard to race, color, sex, or national origin.
LIST OF TABLES
Page
1. Input Data File for Weather Data ................ ............................ 10
2. Input Data File for Plant and Soil Parameters ...... ... ....................... 11
3. Output Data Files on Disk .............................................. 17
4. Output Data Sent to Screen or Printer During Initiation of the Model .................... 18
5. Output Data Sent to Screen or Printer During Current Simulation Run .................. 19
LIST OF FIGURES
Page
1. Hypothetical soybean plant growing in a one-dimensional layered soil, consisting of
uniform layers in the horizontal direction. ............. ............................. 5
2. Forrester flow diagram for carbon balance algorithm . .............. ........................ 6
3. Forrester flow diagram for water balance algorithm ................ .................... 6
4. Simulated rate of instantaneous global radiation from day 230 to day 240, computed by
WAVE algorithm....... .............................................................. 7
5. Simulated air and soil temperatures during days 230 to 240 ................................. 7
6. Soil water conditions for the 1983 growing season......................................... 9
7. Simulated water potential at a depth of 0.4 m from day 150 to day 250 ..................... 12
8. Simulated canopy water potential from day 230 to day 240 ................................. 13
9. Simulated canopy apparent photosynthesis from day 230 to day 240 ........................ 13
10. Simulated partitioning factor for dry matter from day 230 to day 240.................... 13
11. Simulated growth and death rates of the shoot system from day 230 to day 240............. 13
12. Simulated growth and death rates of the root system from day 230 to day 240 .............. 14
13. Simulated dry matter accumulation in the whole plant, the shoot system, and the root
system from day 150 to day 250. ................................. .. ............ 14
14. Simulated increase in leaf area from day 150 to day 250 .............. ...................... 14
15. Simulated increase in total root length from day 150 to day 250 ............................ 14
16. Simulated root growth from day 150 to day 250. ................ .................... 15
17. Simulated net change in root length between day 230 and 240 ............................. 15
18. Simulated soil water uptake between day 230 and day 240 ................................. 16
INTERPRETIVE SUMMARY
ROOTSIMU is a computer simulation model which de-
scribes the complex of interactions between the shoot and
root systems of a crop growing vegetatively in a soil-plant-
atmosphere continuum. The model contains both a carbon-
balance algorithm to account for many fundamental plant pro-
cesses and a water-balance algorithm to account for water
movement through both the plant and bulk soil. Maintenance
of a functional balance between shoot and root size is facili-
tated by partitioning growth between new root and shoot tis-
sue according to plant water potential. Readers are referred
to Huck and Hillel (21) for additional, detailed discussions of
the model logic. The model was originally developed on a
mainframe computer, but versions are now available for mini-
and micro-computers.
ROOTSIMU V4.0
A Dynamic Simulation of Root Growth, Water Uptake, and Biomass Partitioning
in a Soil-Plant-Atmosphere Continuum: Update and Documentation
1
GERRIT HOOGENBOOM and 
M.G. HUCK
2 ,3
INTRODUCTION
A N EARLY VERSION of the model ROOTSIMU (ver-
sion 1.5) has been described by Huck and Hillel (21). They ex-
plained their underlying assumptions and presented exam-
ples based on the use of a sine-function as the driver for the
calculation of air and soil temperature and radiation inter-
cepted by the canopy. The original version of the model per-
mitted testing the plausibility of assumptions, but its predic-
tions could not be tested against measured data because no
provision for input of climatic data was included in the code.
ROOTSIMU version 1.5 of the model was developed in Con-
tinuous System Modeling Program, an IBM computer simu-
lation language referred to as CSMP3 (24,36). CSMP con-
tains integration and plotting subroutines and several other
special functions and, therefore, it facilitates easy modifica-
tions and expansions of the source code.
A modification of the model is presented which permits the
use of measured climatic data as driving functions. Arbitrary
functions are generated by interpolation between known data
points as described earlier (21). This new revision of the
model (ROOTSIMU version 4.0) permits a comparison of
predictions from the computer run under simulated condi-
tions with experimentally determined data. The discrete
daily input data, which are used to simulate the continuous
weather conditions, are almost identical with those observed
in actual experiments from which measurement data were
obtained. However, the daily summation of each input vari-
able is now adjusted to match observed values. Sections of
the model which calculate photosynthesis and shoot and root
growth also were revised.
The primary purpose of this publication is to incorporate
the real weather capability into the model ROOTSIMU and
to describe further modifications in other sections of the
model. It includes a listing of the model ROOTSIMU version
4.0 in CSMP and FORTRAN and instructions to run the
model on either a mainframe, mini-, or micro-computer.
Examples comparing predicted soybean root growth and
water movement with actual experimental data from the 1981
growing season will be published by Hoogenboom et al. (17).
Presented herein are some examples of soybean plant growth
'Part of a dissertation submitted by the senior author in partial fulfillment
of the requirements for the Ph.D. degree.
'Graduate Research Assistant of Agronomy and Soils 
(presently, Post-
doctoral Associate, Department of Agricultural Engineering, University of
Florida) and USDA Soil Scientist (presently at Department of Agronomy,
University of Illinois), respectively
'Mention of a trade name is solely for the convenience of the reader and
does not imply endorsement of that product to the exclusion of others by the
U.S. Department of Agriculture or by Auburn University or its employees.
data predicted by the simulation model for the 1983 growing
season. Soybean (Glycine max [L.] Merr.) shoot and root
growth as measured under experimental conditions during
the 1983 growing season will be published elsewhere (18,23).
In the following examples, data recorded by a standard Class
"A" weather station during the summer of 1983 (1) and sum-
marized on a daily basis were used as a driver for the climate
sections of the model.
MODEL DESCRIPTION
The quantitative model ROOTSIMU, Appendix A-C, is a
set of equations which describes the complex of interactions
between the shoot and root systems of a crop growing vege-
tatively in a one dimensional soil profile, arbitrarily divided
SOIL SURFACE Boundary 1
Flx 
1- 
_ Boundary 
2
aept.3_-Boundary 4
Dis tance
I i ac t------ -------- - -
Flux 4
Layer 4 
_ Boundary 5
Boundary n+1
_ Boundary n+2
FIG. 1. Hypothetical soybean plant growing in a one-dimensional lay-
ered soil consisting of uniform layers in the horizontal direction.
into discrete layers, figure 1 (20). The 
model contains both
carbon-balance and water-balance algorithms to describe r----
such fundamental processes as photosynthesis, 
respiration,
vegetative growth of shoot 
and root tissues (computed inde- 
WATER VAPOR
pendently), transpiration and soil water uptake 
by roots, and
water movement through bulk soil including effects of irri- 
CANOPY WATER
gation, rainfall, and drainage. EVAPORATION TRANSPIRATION POTENTIAL
The carbon-balance section computes a photosynthetic 
rate
per unit leaf area from regression-based 
temperature andPLANTWATER
photosynthetic active 
radiation (PAR) functions. 
Self-shading,
when the leaf area index (LAI) is greater than 1, and stomatal 
ROOT LENGTH
closure, induced by low plant water potentials (p,,lant), reduce POT. RRADIEN
photosynthesis. Soluble carbohydrates derived from 
photo-
synthesis accumulate in a labile pool accessible to each 
or-
gan. The soluble carbohydrates are withdrawn from this pool LAYERF
and are used in growth and respiratory processes at indepen- |SOL WATER
dently computed rates for each process. Maintenance respi-
ration depends only on temperature and 
tissue mass, but LAYER2
growth respiration also depends upon the size of the reserve- ISO1L WATER FLOW
carbohydrate pool, figure 2. Shoot tissue necrosis 
is a func-
tion of leaf age and LAI, because at an LAI greater than 1 the LAYER 3
lower leaves on the canopy are shaded by the upper leaves.
Root death rate is a function of root age and carbohydrate re- +
serve level. Maintenance of a functional balance betweenLAYERn
shoot and root size is facilitated 
by partitioning growth be- 
ISOL WATER FLOW
tween new root and shoot tissue according to Jplant (computed
from tissue relative water content). 
As ,pIant plant declines 
LAYER n+1
with depletion of stored soil water reserves, root growth in-
creases and shoot growth declines. Roots grow more rapidly DRAINAGE RATE MATRIC POTENTIAL
TCANADI PHTOYNHES--- -- -FIG. 3. Forrester flow diagram for water balance algorithm.
POTENTIAL
in wetter parts of the soil profile than in the drier parts of the
soil profile, so younger roots with higher tissue conductivity
SOLUBLE CARBOHYDRATES form in wet soil, while 
older, non-functioning roots die in dry
soil.
The water-balance section computes evaporative demand
from incoming solar radiation and partitions water loss be-
- ROOT RESPIRATION RATE TEMP. TEMP. HOOT RESPIRATION RATE - tween transpiration 
and soil surface evaporation, according
CANOPY to LAI (soil shading) and hydraulic conductivity of the soil
WATER
POTENTIAL surface layer (a function of its water content). Internal water
co
2  
CO redistribution and sub-surface drainage are computed from 4t
FRACTION gradients in bulk soil, while soil water 
uptake by roots is a ca-
tenary function of tj differences between leaves, root surface,
RESERVE LEVEL TEMPERATURE and the water held in each soil layer, figure 3. A more detailed
---- ROOT GROWTH RATE 
SHOOT GROWTH RATE SERVE LEVEL 
description of the basic logic 
of the carbon-balance and 
water-
balance section of the model is given by Huck and Hillel (21).
H MS MODEL 
MODIFICATIONS
RESERVE LEVEL TEMPERATURE 
The descriptions and code of the aboveground (shoot) por-
-- ROOT DEATH RATE SHOOT DEATH RATE AGE....... tions of the 
model have been extensively revised to include
recorded weather data for driving the model. Modules were
taken from the published work of de Wit et al. (40) and Goud-
riaan and van Laar (11) and revised to fit this model, Appen-
DEAD ROOTS) DEAD LEAVES dix A. The automatic 
sort algorithm, which is a feature of
CSMP, facilitated revisions to the CSMP simulation language
FIG. 2. Forrester flow diagram for carbon balance algorithm. source code (41). The UPDATE subroutine generated by the
[6]
CSMP translator was kept, modified, and stored as FOR-
TRAN code.
This version of the model will run on a wide variety of
mainframe, mini-, and micro-computers as an independent
FORTRAN language program, Appendix B. Machine-
readable copies of either source code are available from the
authors on a 5.25-inch diskette or by direct transmission elec-
tronic mail. An earlier version of the model (ROOTSIMU
version 1.5) is available in Advanced Continuous Simulation
Language identified as ACSL, Mitchell and Gauthier Assoc.
(28), Appendix C. Basically, the simulation languages ACSL
and CSMP are similar. However, in contrast to the simulation
language CSMP which can only run on an IBM mainframe
computer, the simulation language ACSL is available on a
broader range of computers, including micro-computers.
4
In m
ated cr
weather
meteor
was wri
discrete
from st
tion fun
continu
(macro
posed b
CSMP,
continu
temper
use of si
nal ter
model,
named
the fori
model.
Inter
irrigati(
temper
trated h
a const
A new
cation on
12C
I)
cN
E
")
z
0
a
cr
FIG. 4. S
to day 2'
Weather Data
any applications when soil water relations and associ-
op performance are simulated, the only long-term
1 A - .,__ A -- -- 11 , 1_L _ 1 1 -_ . 1
ci:
0
LU
I-
CALENDAR DAY
FIG. 5. Simulated air (TEMP) and soil temperatures (STEMP) during
days 230 to 240. Both temperatures are calculated by forcing a sine
function through the daily maximum air (MAXTEM) and soil temper-
atures and daily minimum air (MINTEM) and soil temperatures.
Sata avaiiabe are tose colected y a conventional corded. The instantaneous potential evapotranspiration (ET)
ological observation station. Therefore, this model rate was interpolated from daily 
total pan evaporation mea-
tten to include sections for interpolating between the surements and proportioned 
according to the instantaneous
points (usually recorded 
at daily intervals) obtained 
radiation. Shaw and Laing 
(34) reported that, at full 
canopy,
andard weather observations. 
The CSMP interpola- 
the evapotranspiration rate 
of soybeans is 90 percent of 
open-
ctions AFGEN and NLFGEN 
were used to generate 
pan evaporation. Similar 
observations were reported 
by
ous data between measured 
data points. A macro 
Hanks (13) and Mason 
et al. (27). Alternative 
methods for
is the equivalent of a subroutine) 
named WAVE, pro- 
computing ET rate, such 
as the energy-balance 
method of
)y de Wit et al. (40), has been 
incorporated into the 
Penman (30), can be substituted 
by the user if adequate mea-
version of our model, Appendix 
A. This produces a surement 
data to support the desired 
computation method
ous sine curve 
connecting maximum 
and minimum 
are available.
ature values. Floyd and 
Braddock (8) reported 
that Length of the 
daily light period (LSNHS), 
height of the sun
ne curve fitting can be an accurate way to model diur- 
(SNHSS), and the time of sunrise (RISE) are computed 
each
aperature curves. The FORTRAN version of the day from geometrical calculations based on latitude (LAT)
Appendix B, includes a homologous subroutine 
and season (declination of the sun [DEC]). 
Daily totals for
WAVE which produces continuous-function 
output of maximum 
and minimum solar radiation, 
for a completely
rm required by the defining 
equations used in the 
clear day (DRC,DRCP) 
or for a completely overcast 
day
(DRO, DROP), respectively, are 
estimated as a function of
polation schemes for solar radiation, rainfall (and/or sun height, based on the assumptions of de Wit et al. (40).
on events), open-pan evaporation, and air 
and soil These computed daily solar 
radiation totals are then com-
ature are included in the versions of the model 
illus- pared with the measured solar radiation 
(DTRR, DTR) ob-
ere. Rainfall was assumed to infiltrate the 
surface at served for that day, and 
the ratios between measured radia-
ant rate over the full 24-hour day when 
it was re- tion and that expected for 
a clear day or for an overcast day
version of CSMP called PCSMP has become available for appli- are computed (LFCL, LFOV). Finally, an instantaneous rate
micro-computers. for solar 
radiation (RADIAT) is computed along a half-sine
)0 curve using the proportions of diffuse and clear-sky radiation
computed earlier. The net effect of these computations de-
fines a continuous function, figure 4, which resembles figure
3 of Huck and Hillel (21) except that each day's total radiation
0 is now adjusted to match that observed by the meteorological
instrumentation.
Linear interpolation between successive daily minimum
Do- 
and maximum air temperatures (MINTMPMAXTMP) 
pro-
vides a variable-width band, figure 5, within which WAVE
generates a sinusoidal air temperature function with period-
icity determined by the length of the daily light period. The
0 . . -. same WAVE function is used to generate instantaneous soil
230 232 234 236 238 240 
temperatures between successive daily minimum 
and maxi-
CALENDAR DAY mum soil temperatures (MNSTMP, MXSTMP). 
It is assumed
imulated rate of instantaneous global radiation from day 230 that 
the daily minimum and maximum soil temperatures oc-
40, computed by WAVE algorithm, cur with a delay of 3 hours, compared to the minimum and
[7]
8(
4(
maximum air temperatures, and that the same soil tempera-
ture is observed throughout the whole soil profile.
Carbon Balance
One of the principal changes from version 1.5 of the model
is the inclusion of a section for predicting photosynthesis and
plant growth patterned after the BACROS model of de Wit et
al. (40) and presented in simplified form by Goudriaan and
van Laar (11). The model ROOTSIMU computes two photo-
synthetic rates: PHOTC, the maximum canopy photosyn-
thetic rate under a completely clear sky, and PHOTD, the
maximum possible photosynthetic rate under a completely
overcast sky. Adjustments for shading within the canopy
(based upon LAI) are made according to the method de-
scribed by Goudriaan and van Laar (11). Based on data re-
ported by Shibles and Weber (35), it is assumed that 100 per-
cent of the incoming radiation is intercepted by the soybean
canopy if the LAI is larger than three. Respiration, assimi-
lation, and growth are treated as in the earlier version 1.5 of
this model.
Version 1.5 of this model (21) considered partitioning of
carbohydrates only between the root system (ROOTW) and a
shoot system (SHOOTW) consisting of a single compartment.
The shoot system compartment has been expanded to include
separate compartments for leaf (LEAFW) and for 
stem tissue
(STEMW), which permits a more accurate representation of
canopy architecture, figure 1. It 
is assumed that stems only
respire and that their photosynthetic capacity is small com-
pared with the leaves, because of the relatively small surface
area of the stems. It is assumed that the leaves, on the other
hand, carry on both photosynthesis and respiration. Although
it is known that the specific leaf area of soybean leaves varies
with time and position (25), a constant specific leaf area is as-
sumed in this model (12,33).
Additional constraints have been imposed on root growth
in the model. For instance, a maximum root density is im-
posed: the total volume of roots in any soil compartment can
never exceed a set fraction of the total pore-space. This allows
for incorporation of a plow layer and other factors which in-
crease soil strength and cause a reduction in root growth (10).
Taylor and Klepper (37) reported that the rooting volume de-
pends on both species and environment. The volume of roots
(ROOTVL) is computed from root mass (ROOTWT), diam-
eter (LNGFAC), and density (PRTL). Soil porosity (POROS)
also is computed for each layer, based on bulk density
(BULKDS), which is a function of depth (DEPTH) and par-
ticle density (PARTDS).
It is further assumed that the propensity for new root
growth (BIRTH) and extension of existing roots (EXTENS) is
inversely proportional to depth, which takes into account the
longitudinal resistance to carbohydrate and water transport
in the phloem tissue. Vertical extension of roots into a new
layer can only occur when root length in the other layer ex-
ceeds a minimum threshold, MINRTL. No root growth is
permitted in the lowest soil layer, which is assumed to rep-
resent a buffer between the water table and the soil layers in
which the roots are growing actively, figure 1. Because sim-
ulated root growth is highly responsive to soil moisture con-
ditions, a soil layer which is saturated with water might show
an excessive amount of root growth, compared with the other
drier soil layers. In the previous version (1.5) of the model, an
unreasonably large mass of root tissue was predicted in the
undrained bottom layer.
Water Balance
Validation data were obtained from the experiments of
Huck et al. (22,23) in which soybean shoot and root growth
was measured in the Auburn rhizotron under two different
water regimes. The nonirrigated treatment (NI) was simu-
lated by adding only the observed rainfall (RAIN) to the sur-
face soil layer. In addition to observed rainfall, 250 c m3 
-3 
of
irrigation water (IRQUAN)was automatically (PULSSW)
added to the simulated irrigated treatment (IR) every 30 min-
utes (PULSIR) whenever the computed soil water potential
(soii) at a depth of 0.4 
m dropped below -15 kPa 
(IRMIN). In
the rhizotron experiments, the trickle irrigation system was
switched on for 3 to 5 minutes at hourly intervals whenever
the tensiometer readings at a depth of 0.4 m fell below -10 to
-15 kpa (23). An example of the soi measured by tensiome-
ters at a depth of 0.4 m during the 1983 growing season is pre-
sented in figure 6.
The Darcian flow equations used to compute unsaturated
water flow (NFLW) between layers has been retained in this
version of the model, but infiltration is based on the assump-
tions of Green and Ampt (12). Water flows from the surface
into deeper layers at a rate controlled by saturated conductiv-
ity (SATCON), but only when the matric potential of the con-
ducting layer is near 0. Since each increment of added water
begins percolation in the surface layer, the FLPFLP (flip-
flop) function used in version 1.5 of the model (12) was elim-
inated. Each iterative calculation to balance water uptake by
the roots, water flow in the soil and the plant, and transpir-
ation now begins at the surface. When soil water content of
any layer reaches saturation, flow through that layer is as-
sumed to occur at the maximum (saturated conductivity)
rate. Water is allowed to drain from the bottom layer to pre-
vent accumulation in the soil profile (DRAING).
Relative conductivity was redefined as proposed by van
Genuchten (38), and calculated as a function 
of soil matric po-
tential. The constants 'a' (ALPHA) and 'n' (NU) were deter-
mined by nonlinear least-square analysis fit of the soil water-
retention data (38). Possible vapor phase transport and the ef-
fects of entrapped air were ignored.
MODEL INITIATION
Weather Data
Weather data used as drivers for the model included: daily
total solar radiation (RADN; Watt hours day
-1 
or Joule day-l);
daily minimum and maximum air temperatures (MINTEM,
MAXTEM; degree Celsius or Fahrenheit); daily minimum
and maximum soil temperatures (MINSTM, MAXSTM; de-
gree Celsius or Fahrenheit); daily rainfall (CMRAIN; cm
day
-
' or inches day
-
') and daily open pan evaporation (PEVAP
cm day
-1 
or inches day -). Because the units in which weather
data are recorded vary from weather station to weather sta-
tion, the numbers must be converted into SI units for the
model to function. Weather generators can be used if one or
more input variables are missing. For instance, when no soil
[81
170 180 190 200 210 220 230 240 250 260 210 280 290
0 i "i , ._ j ... 1
10
20
E 
30
0
? - 40
qt
0
a-
50
I 60
70
80
170 180 190 200 210 220 230 240 250 260 270 280 290
CALENDAR DAY
VO VI V2 V3 V5
I- VEGETATIVE
V8RI R2
I
R3 R4 R5 R6 R7
REPRODUCTIVE I
GROWTH STAGES
FIG. 6. Soil water conditions for the 1983 growing season. Above: Measured soil water potential at a depth of 0.4 m during the 1983 growing
season (tensiometer readings below -50 kPa are subject to error). Below: Rainfall 
during the 1983 growing season and growth stages (6). 1
temperature data are available, it might be assumed that the
soil temperature has a lag phase of 3 hours relative to air tem-
perature.
The weather data used in demonstrating version 4.0 of the
model were recorded during 1983 by the weather station at
the Alabama Agricultural Experiment Station (1) located in
Auburn. An example of the raw weather data for 1983 in the
model is given in table 1. For calendar days 150 to 174, the val-
ues shown represent, from left to right, in units as reported
by the weather station, daily total radiation (Watt hours),
daily maximum air temperature and daily minimum air tem-
perature (Fahrenheit) measured at a height of 5 feet (1.5 m)
above the soil surface, daily total rainfall (inches), daily total
open pan evaporation (inches), and daily maximum soil tem-
perature and daily minimum soil temperature (Fahrenheit)
measured at a depth of 4 inches (0.1 m). The year and cal-
endar day are given at the far right on each line. In the model,
the units of the input variables are converted into SI-units.
Plant Material
ROOTSIMU is a general root-growth model and can be
used to simulate any type of plant, providing initiation vari-
ables and growth parameters are available. However, the in-
put plant parameters used for this demonstration were cho-
sen to match those of soybeans used for the validation data
set collected at the Auburn rhizotron (18,19,22,23). The
starting day of the year (PARAM START = 150), the number
of simulation hours (FINISH HOURS = 2400 hours), and the
site of the crop (PARAM LAT = 32.5 degree) were defined
to match the actual crop grown. The initial shoot mass
(PARAM ISHOOT - 0.010 kg m
- 
2) was set to a value repre-
senting the mass of the first trifoliolate leaf as it was observed
on day 150. A partitioning factor for weight distribution be-
tween the leaves and the stem (PARAM STWTR = 0.25) and
a specific leaf area parameter (PARAM LEAFTH = 30m
2
kg 1)
were defined (33). For the roots, an initial root mass (PARAM
[9]
6.0
0
4.0 E
2. J
2.0,,i.
z
Table 1. Input Data File for Weather Data
From left to right, daily 
total solar radiation (RADN), 
daily
maximum air temperature (MAXTEM), daily minimum 
air temperature
(MINTEM), daily total rainfall (CMRAIN), daily total open pan
evaporation (PEVAP), daily maximum 
soil temperature (MAXSTM), 
daily
minimum soil temperature (MINSTM), year (YEAR), 
and calendar day
(DAY)
RADN MAXTEM MINTEM CMRAIN PEVAP MAXSTM MINSTM YEAR DAY
W.hour F F Inches Inches F F
5518 87.0 62.0 0.15 0.29 92 70 083 150
7397 88.0 62.0 0.00 .46 89 69 083 151
7377 83.0 59.0 0.00 .33 93 70 083 152
5666 78.0 53.0 0.00 .24 89 69 083 153
7700 83.0 60.0 0.00 .27 95 70 083 154
6943 88.0 64.0 .09 .30 96 74 083 155
5463 84.0 62.0 0.00 .20 92 75 083 156
4399 84.0 62.0 0.00 .16 91 75 083 157
5080 82.0 65.0 .48 .21 90 70 083 158
1511 72.0 58.0 .57 .09 76 68 083 159
7127 80.0 59.0 0.00 .26 86 68 083 160
6084 82.0 61.0 0.00 .23 86 68 083 161
7294 82.0 59.0 0.00 .31 89 68 083 162
7622 83.0 61.0 0.00 .33 92 70 083 163
7741 83.0 63.0 0.00 .38 94 71 083 164
7910 84.0 61.0 0.00 .37 97 73 083 165
6878 86.0 56.0 0.00 .26 97 73 083 166
6670 88.0 61.0 0.00 .26 97 74 083 167
5753 90.0 67.0 0.00 .17 98 76 083 168
4551 85.0 65.0 .23 .21 92 75 083 169
4108 83.0 65.0 .42 .24 87 73 083 170
2826 82.0 65.0 .47 .14 82 71 083 171
4944 82.0 67.0 0.00 .20 85 72 083 172
3218 79.0 67.0 .01 .14 81 73 083 173
4728 87.0 69.0 .02 .17 89 74 083 174
IROOT = 0.002 kg m-2), factors for root growth distribution
over the top soil layers (TABLE RRL(1-10) - 0.54, 
0.38,
0.08, etc.), and root length to root mass ratio (PARAM
LNGFAC - 13000 m kg
-
1) were determined from the exper-
imental plants on day 150.
The photosynthetic parameters are defined for C3-plants in
general, but can be adjusted if necessary: maximum photo-
synthetic rate, PARAM MXPHOT = 0.82 * 10-6 kg m
-2 
S
-
1,
(39,11) a light efficiency factor of the photosynthesis process,
PARAM EFF = 0.01388 * 10-6 kg J-1 s
-
1, (3,26,11); a mainte-
nance respiration factor, PARAM RSPFAC = 1.0*10-
7
kgkg-ls
-1
(31,32); a conversion efficiency factor, PARAM CONVRT =
0.30 kg kg
-
I (31,32), and a growth factor, PARAM GROFAC =
1.0 * 10
-5 
kg kg
- 
s-1, (40).
The model also includes an aging and senescence factor
for shoot tissue (PARAM AGFAC) 
which was set at 3.0 * 10-
kg kg
-
' s
-
I and a death factor for root tissue (PARAM
DTHFAC) which was set at 1.0 * 10-8 kg kg
- 
s
-
~. Both of these
gave a good fit to the experimental data, although shoot and
root death rates were not actually measured.
FRAC is a factor which partitions dry matter between the
shoot and the roots, based on canopy water potential. The
function FRACTB, which is used to compute an instanta-
neous value for FRAC, was redefined. Similarly, the function
LAIFAC, which is the basis for computing photosynthetic rate
from LAI and partitions water loss between the canopy and
the soil, was redefined. Both functions can be adjusted when
data are available. The water stress table (FUNCTION
TRNTBL) was adapted from data for soybean plants (5), but
the data in the table can be substituted with other values for
different crops.
Root growth was divided into root branching, which was
the formation of new roots and the extension of older roots in
the same soil layer, and root extension which was the exten-
[10]
Table 2. Input Data File for Plant and Soil Parameters
(Corresponding to READ Statement in FORTRAN Program)
Time variables 1
OUTDEL PRDEL
01.0 3599.9999DO0
DELT
1800.0
BGNDAY
150.
Initial mass variables 1
ISHOOT IROOT
0.010 0.002
LGNFAC NJ RTDWPC
13000.0 10 10.
Soil variables 1
ITHETA(I), I=1,NJJ
0.200 0.200 0.200 0.200 0.200 0.200 0.200 0.200 0.200 0.230 0.300
RRL(I), I=1,NJ
0.54 0.38 0,08 0.00 0.00 0.00 0.00 0.00 0.00 0.00
TCOM(), I=1,NJJ
0.10 0.15 0.15 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20
HIPOT
-100.0
SATCON ZAM
5,OE-05 .64162
PARTDS THTAIR STHETA ALPHA
2.59 0.050 0.36 0,24890
Growth variables 1
REFTS RSPFAC MXPHOT DKPHOT EFF
25.0 1,OE-01 0,8200E-6 
0.OOE-6 0,01388E-6
REFT
25.0
CON VRT
.3
DELAY FRG
21600 0,666
GROFAC DTHFAC PB
1.OE-05 1.OE-08 21.8258
.BR EXTNRT AA
1.OE-04 3,OE-03 8.OE-03
URRS UARS MAXPOT
1,OOE+11 1.OOE+11 -2.0
POTCR
-2.00
LSNHS DRCI
-0,500 3,5E+07
CF ERROR
0.100 0.010
AGFAC
3.OE-7
LEAFTH STWTR
30.00 0.25
BRMIN EXTMIN MINRTL
-1.0 -2.0 5.0
BB
2.0
B DEPTHG
1.OE-02 10.
OUTF
3. 024 ECS
DROI DRADI
6,6E06 1.OE-10
LAT
32.5
[1]
FINTIM
4320000
IPER
0.03
LOPOT
-110.0
DTRDEM
0.01
NU
1.,21555
'Definition and unit for each variable are given in Appendix D.
sion of root from one layer into the next layer. A relative
branching factor (PARAM BR) was set at 1.0 * 10-4 m s
-1 
and
the minimum soil at which root branching terminates
(PARAM BRMIN) was defined as -10 kPa. A relative exten-
sion factor (PARAM EXTNRT) was set at 3.0 * 10
-3 
m s
-1 
and
a minimum soil at which root extension from one layer into
the next layer terminates (PARAM EXTMIN) was defined as
-20 kPa. A factor to reduce root growth at increasing depth
(PARAM DEPTHG) was set to 10 m m1.
Although measured root water uptake is more closely re-
lated to total root surface area (7), in this model, root resis-
tance and water uptake rates are based on root length, which
assumes a linear relationship between root length and root
surface area (7). For root water uptake, an axial resistance
(PARAM UARS = 1.0 * 1011 smm 1), a radial resistance
(PARAM URRS = 1.0 * 1011 s m), and a factor relating soil
conductivity, root length, and root conductivity, PARAM B =
0.01 m-1 (9) are required. The input parameters needed to de-
fine the initial plant conditions are shown in table 2, which is
set up in the format to be read by the FORTRAN program in
Appendix B and can be adjusted by the user. For instance,
the first line in table 2 shows, respectively, the finished con-
dition in seconds for the simulation run (FINTIM), the out-
put intervals for plotting (OUTDEL) or printing (PRDEL),
the time step of each simulation interval (DELT), and finally
the starting day of the simulation run (BGNDAY).
Soil Conditions
Soil conditions are an important part of the model and
greatly influence the results of the simulation. The experi-
mental plants were grown in the A-horizon from a Dothan
loamy sand (fine loamy, siliceous, thermic Plinthic Paleu-
dult). A soil-water retention curve for this soil material was
experimentally measured in the laboratory and used as a ba-
sis for defining the function SUTB. Saturated water content
(PARAM STHETA = 0.36 m
3 
m- 3), air dry water content
(PARAM THTAIR = 0.050 m
3 
m-3), bulk density as a func-
tion of depth (FUNCTION BULKF), and particle density
(PARAM PARTDS = 2.59 Mg m
-
3) were also measured in the
laboratory and used as input parameters in the model (4). To
calculate water flow, a saturated conductivity (PARAM
SATCON = 5.0 * 10-
5 
m day
-
1) and the constants to define the
van Genuchten (38) equation for calculating relative conduc-
tivity must be defined (PARAM ALPHA = 0.24890; PARAM
NU = 1.21555).
In this revision of the model, the homogeneous soil profile
was arbitrarily divided into 10 layers (PARAM NJ = 10) of
0.20 m (TABLE TCOM(1-20) = 0.10, 2*0.15, 17*0.20 m) ex-
cept for the three top layers, which were 0.10, 0.15, and 0.15
m, respectively. The thickness of each layer can easily be ad-
justed if necessary.
The model provides an option for simulating irrigation
treatments. A minimum soil threshold matching the tensiom-
eter readings (PARAM IRFAC = 10 kPa) and the amount ap-
plied per irrigation pulse (PARAM IRQUAN = (0.0, 250.0
cm
3 
m
-
2) were defined.
Most of the initial soil conditions are shown in table 2,
which represents an input file read on device #8 for the
FORTRAN version (Appendix B) of the model. When the
CSMP version of the model is used, both the IR and NI treat-
ments can be run simultaneously and the results can be over-
layed on plots.
MODEL RESTRICTIONS
One of the main limitations of this revision of the model is
that it has no provisions for partitioning dry matter into re-
productive structures such as flowers, pods, or seeds. Be-
cause Braxton (maturity group VII) soybean plants continue
vigorous vegetative growth throughout the full-bloom (R2)
and beginning pod-set (R3) stages (6), this portion of the
growing season was included in the simulation examples pre-
sented below. When plants began full pod development (R4)
and early-seed-filling stages (R5), most of the available dry
matter was stored in pods and seeds. Thus, this version of the
model, which accounts for vegetative growth only, cannot ad-
equately describe carbon partitioning during seed formation
and maturation. Therefore, only the first 100 days of the
growing season, during which most of the vegetative soybean
growth occurs, were simulated.
Because the model was developed mainly to simulate the
effect of water stress on plant growth, it was assumed that the
supply of nutrients would be optimal and that growth would
not be inhibited by insects, diseases, or weeds. The model
also did not account for soil environmental constraints (21),
such as poor aeration, temperature extremes, salinity, or
chemical toxicity, although they could be included if data
were available. Some of these simplifications and assump-
tions of the model will be replaced by newly coded algorithms
as the model is extended.
MODEL PREDICTIONS
Only predictions for the 1983 growing season are pre-
sented herein. Detailed trial simulation runs for the 1981
growing season, including comparisons between observed
and simulated data, are described by Hoogenboom et al. (17).
Environmental Conditions
Figure 4 shows the intensity of solar radiation expressed as
a continuous function over a 10-day period of the growing sea-
CALENDAR DAY
0
CC
175 250
POTM (4)
o Irrigated
* Nonirrigated
FIG. 7. Simulated water potential (POTM(4)) at a depth of 0.4 m from
day 150 to day 250.
[12]
son as interpolated by the computer from measured daily to-
tals. Soil and ambient-air temperature over the same 10-day
period are shown in figure 5 (TEMP,STEMP), including the
daily maximum (MAXTEM) and minimum (MINTEM) air
temperature. Rainfall events as measured at the Auburn rhi-
zotron are presented in figure 6. This figure also presents the
experimentally measured qsoil for the 1983 growing season,
while the simulated W,o is shown in figure 7. The data for ex-
perimental and simulated NI treatments show low soji during
the period without rainfall from day 205 to 215 and from day
225 to 250. Detailed model predictions from day 230 to 240
are presented in the next simulation examples, because dur-
ing this period strong differences between IR and NI plants
were observed.
Plant Growth
Because little rain was observed between days 230 and
240, figure 6b, canopy water potential ( anopy) of the simu-
lated NI plants reached lower values than canopy of simulated
IR plants as the drought period continued, figure 8. Although
simulated canopy and therefore water stress levels were differ-
ent with the two treatments, no differences were observed
between simulated photosynthetic rates, figure 9. The lower
.anopy of the simulated NI plants induced an increasing pro-
CALENDAR DAY
c" 230 232 234 236 238 240
-
Z -0.2
CL
~ -0.4 POTCR
o Irrigated
n> *Nonirrigated
0
z
< -0.61
FIG. 8. Simulated canopy water potential (POTCR) from day 230 to
day 240.
PHOTSN
2.4. o Irrigated
Nonirrigated
0
0.8.
0
I 230 232 234 236 238 240
CALENDAR DAY
FIG. 9. Simulated canopy apparent photosynthesis (PHOTSN) from
day 230 to day 240.
0
CC
LL
CALENDAR DAY
FIG. 10. Simulated partitioning factor for dry matter (FRAC) from day
230 to day 240.
portion of the available dry matter to be used by the roots, as
shown by the partitioning factor FRAC, figure 10. Although
predicted shoot growth of both treatments was similar during
this period, figure 11A, predicted root growth, especially in
the NI plants, increased markedly, figure 12A. Predicted
shoot death rates, figure 11B, increased during this period,
while predicted root death rates had similar maximum rates
every day, figure 12B.
Long term growth of shoot and root mass as predicted by
x
-m
o
CC
0
SHOOTD
0.3
0.2
0.1
Ai
o Irrigated
* Nonirriaated
B
230 232 234 236 238 240
CALENDAR DAY
FIG. 11. Simulated growth and death rates of the shoot system from
day 230 to day 240. A: Growth rates (TOPGRO). B: Death rates
(SHOOTD)
[13]
II ,,,
TOTRG
o
Cl
E
(0
&
x
Lu
I-
O
cc
0
c
(.0
co
x
Lu
LU
0
o Irrigated
* Nonirrigated
A
E
U)
U)
Du
U)
U)
7iTH
250
CALENDAR DAY
FIG. 13. Simulated dry matter accumulation in the whole plant
(DRYWT), the shoot system (SHOOTW), and the root system
(ROOTW) from day 150 to day 250.
12
CALENDAR DAY
FIG. 12. Simulated growth and death rates of the root system from
day 230 to day 240. A: Growth rates (TOTRG). B: Death rates
(ROOTDY).
the model is presented in figure 13. Although there was no
difference in simulated total dry weight of the two treat-
ments, simulated IR plants had a larger shoot and therefore
more leaf area, figure 14. On the other hand, simulated NI
plants had a heavier root system with larger total root length,
figure 15. The difference between the predicted root lengths
of the two treatments was mainly found in the deeper soil lay-
ers, figure 16D, similar to experimental observations (18,19).
No root growth was predicted in the surface layer for either
treatment, figure 16A. Most of the predicted root growth was
found between a depth of 0.25 and 1.00 m, figure 16B and C.
The simulated IR plants had a larger root system between a
depth of 0.60 and 1.00 m, while simulated NI plants had a
larger root system between 1.00 and 1.40 m, figure 16C and
D.
During the drought period between days 230 and 240, fig-
ure 6, a decrease in simulated net root growth occurred
above 0.40 m, figure 17A, in the NI treatment. Simulated IR
plants formed roots mainly between 0.25 and 0.80 m, while
simulated NI plants formed roots mainly between 0.80 and
1.40 m, figure 17. The model predicted no water extraction
from the top layer, because it was extremely dry due to evap-
oration. It therefore contained only the tap root and no small
feeder roots, figure 17A. Simulated IR plants mainly ex-
tracted water between 0.25 m and 0.80 m, figure 
17A and B,
while NI plants mainly extracted water between 0.80 and
1.20 m, figure 17C and D. Predicted water extraction pat-
N
E
x
w
z
uJ
w
U-
w
UJ
rr1
LAI
* Nonirrigated
8- o Irrigated
4-
0 ... 
..
175 200 225 250
CALENDAR DAY
FIG. 14. Simulated increase in leaf area index (LAI) from day 150 to
day 250.
2.4-
EO ROOTL
Or * Nonirrigated
X 1.6 o Irrigated
E
0
Z 0.8
Lu
E-
0
O0
CC 0
150 175 260 225 250
CALENDAR DAY
FIG.15. Simulated increase in total root length (ROOTL) from day 150
to day 250.
[14]
150
0.21 0.0Oto0.1lM
9 *Nonirrigated
0oIrrigated
0.1
x
E
o 0.6-
CC
(5
o 0.3-
0
It
01
0.1 to0.25m
A Irrigated
Irrigated A
1 T A
0.6 to 0.8m 0.8to.4m
* Nonirrigated ANonirrigated
o Irrigated tAJrrigated
234 236 238 240
CALENDAR DAY
230 232
I
H-
0
cE
(9
0
0.6-
0.31
1.0 to 1.2m
0 Nonirrigated
o IrrgatD
230 232 *234 236 238 240
CALENDAR DAY
FIG. 16. Simulated root growth from day 150 to day 250. A: Between 0.00-0.10 m and between 0.10-0.25 m. B: Between 0.25-0.40 m and between
0.40-0.60 m. C: Between 0.60-0.80 m and between 0.80-1.00 m. D: Between 1.00-1.20 m and between 1.20-1.40 
m.
750 0.25 to0.4m
e Nonirrigated 
* Nonirrigated
o Irrigated o Irrigated
80- 
500-
0.4 to 0.6 m
A Nonirrigated
40- 0.1 to 0.25 m o 250- 'n Irrigated
E A Nonirrigated E
E Z% 
IrrigatedIE 
1B
wz60 .6 toO0.8 
M 
z1.0to1.2 
m
Noni0igaed 
W 200D
.j 9 Nnirrigted*oNonirrigated 
D
H- ] 0 Irrigated1 o Irrigated
0 A 150-
o 4001 0.8 to1.0Om 
0 1 1.2 to1.4 m
A Nonirrigated
& Irrigated
175 200 225
CALENDAR DAY
A Nonirrigated
&Irrigated
225 250
CALENDAR DAY
FIG. 17 Simulated net change in root length between day 230 and 240. A: Between 0.00-0.10 m and between 0.10-0.25 m. B: Between 0.25-
0.40 m and between 0.40-0.60 m. C: Between 0.60-0.80 m and between 0.80-00 m. D: Between 1.00-1.20 mn and between 1.20-1.40 m.
[15]
.. ..
I I ---- r-
I II\
A
0.6 to 0.8 m 0.8 to 1.0 m
0)
o
x
E
LU
LU
CALENDAR DAY CALENDAR DAY
FIG. 18. Simulated soil water uptake between day 230 and day 240. A: Between 0.00-0.10 m and between 0.10-0.25 m. B: Between 0.25-0.40 m
and between 0.40-0.60 m. C: Between 0.60-0.80 m and between 0.80-1.00 m. D: Between 1.00-1.20 m and between 1.20-1.40 m.
terns, figure 17, were similar to predicted root growth pat-
terns by the simulation model, figure 18.
These examples show some of the capabilities of the model
ROOTSIMU, version 4.0. Other variables, which represent
either an environmental or plant parameter, are involved in
the simulation process. The list of variables included in the
model is given in Appendix D.
SIMULATION INSTRUCTIONS
The examples illustrated herein were generated by the
CSMP version of the model. The UPDATE subroutine gen-
erated by the CSMP translator was kept and stored on disk
on a mainframe computer so that the model could be run in-
dependently. The FORTRAN version of the model has been
adapted and tested, so that results from this version of the
model are the same as those obtained by running the CSMP
version.
Mainframe or Mini-Computer
If a CSMP-package is available on a larger mainframe or
mini-computer, the program can be run in a background
mode, using the proper job control language and weather file
as input data set, table 1. Plant and soil parameters are in-
cluded in the CSMP version of the model. Because CSMP
has a built-in plotting routine, output data sets need not be
explicitly defined, and results will be plotted as specified on
the XYPLOT statements. A similar strategy is applicable if an
ACSL package is available (28).
If no simulation languages are available, the FORTRAN
version of the model can also be run on any larger mainframe
computer with a FORTRAN compiler. This FORTRAN ver-
sion is less dynamic and subroutines must be included for
many of the calculations which are performed automatically
by CSMP or ACSL. The FORTRAN version of the model gen-
erally can be run in a background mode, while specifying
UNIT 8 as input for the plant and soil parameters, table 2,
and UNIT 12 as input for the weather data, table 1. Other de-
vice addresses can be specified as output files. After comple-
tion of the simulation, the output files are saved and then
used for plotting with X-Y plotting routines adapted to the
computer system available. An example of an output file is
presented in table 3. Shown are rates of photosynthesis
(PHOTSN), respiration (RESP), growth (GROWTH), tran-
spiration (TRANSP), evaporation (EVAP), and water uptake
from all soil layers (SUMR) on an hourly (HOURS) basis for
the first 24 hours of simulation, starting on day 150.
Micro-Computer
The following instructions to run the FORTRAN version of
the model on a micro-computer apply only for an IBM
3
-PC or
compatible computer. The FORTRAN source code of Appen-
dix B is compiled, linked, and stored in a binary field named
[16]
"7,
0a)
x
E
w
:D
Ir
w
Table 3. Output Data Files on Disk
From ]eft to right, hours of simulation (HOURS), photosynthetic rate
(PHOTSN), growth rate (GROWTH), respi-ration rate (RESP), tota] water
uptake by the roots (SUMR), evaporation rate ([yAP), and transpiration
rate (TRANSP).
HOURS
1  
PHOTSN GROWTH RESP SUMR EVAP TRANSP
h kg m-
2
s-1 kg m-
2
s-
1 
kg m-
2
s-1 m s-1 m 541 m 541
O.OOOE+O O,754E-18 O.279E-08 O.934E-09 O,228E-09 O9805E-09 O.480E-1O
,100E+01 .754E-18 .241E-08 9162E-08 .235E-09 .824E-09 .492E-10
o200E+01 .754E-18 .214E-08 .146E-08 .242E-09 .844E-09 o504E-1O
,300E+01 *754E-18 *195E-08 .135E-08 .248E-09 .863E-09 *516E-1O
*400E+O1 .754E-18 .184E-08 .129E-08 .254E-09 .883E-09 .528E-10
.500E+01 .754E-18 .178E-08 .126E-08 .255E-09 .903E-09 .540E-10
.600E+O1 .173E-07 .197E-08 .128E-08 .218E-08 .368E-07 .220E-08
.700E+01 .214E-O07.243E-08 .145E-08 .486E-08 .826E-07 .495E-08
,800E+01 .231E-07 .304E-08 .171E-08 7148E-08 .128E-06 7167E-08
.900E+01 *238E-07 .377E-08 .206E-08 .967E-08 .167E-06 .999E-08
.100E+02 .242E-O07.457E-08 .246E-08 .113E-07 .197E-06 .118E-07
,110E+02 .243E-O7 .546E-08 .291E-08 .124E-O07.215E-06 .129E-07
,120E+02 .243E-07 .635E-08 .335E-08 .126E-O07.220E-06 .133E-07
.130E+02 .242E-O07 .718E-08 .373E-08 .123E-07 .215E-06 .130E-07
.140E+02 .240E-O07 .789E-08 .400E-08 .115E-07 .197E-06 .119E-07
.150E+02 .237E-07 ,859E-mO8 .424E-08 .975E-08 .167E-06 .101E-07
,160E+02 .229E-07 .909E-08 .442E-08 7153E-08 .128E-06 .776E-08
.11OE+02 *214E-O7 .919E-08 .449E-08 .491E-08 .826E-O07.502E-08
,180E+02 *175E-O1 .895E-08 .439E-08 .223E-08 .369E-O07.225E-08
*190E+02 .751E-18 .801E-08 .413E-08 .104E-09 .118E-08 *717E-1O
.200E+02 7154E-18 .687E-08 o361E-08 .108E-09 .120E-08 7130E-10
,210E+02 .754E-18 .581E-08 .322E-08 *113E-09 *122E-08 .743E-10
.220E+02 .754E-18 .490E-08 .281E-08 .118E-09 .124E-08 .756E-10
.230E+02 7154E-18 .416E-08 .246E-08 .125E-09 .125E-08 .768E-1O
,240E+02 .391E-18 .355E-08 .216E-08 .129E-09 .127E-08 .781E-10
lDefinition and unit for eac h variable are given in Appendix D.
ROOTSJMU. EXE. To run this FORTRAN -compiled version
of the model simply type:
ROOTSIMU
The program will respond with:
File name missing or blank
Please enter name : UNIT8 ?
Then type:
INPUTSG.FIL (inputs as in table 2)
to read the plant and soil parameters, presented in table 2.
UNIT12 ?
Then type:
DAT1983.FIL (inputs as in table 1)
to read the weather data, presented in table 1.
UNIT6 ?
Then type:
CON for console (display or keyboard) or
LPT1 or PRN for printer.
The program will now start reading the data and weather files
and will print the first line of the weather data set
150.0 0.20E?+08 30.56 16.67 0.38 0.74 33.33 22.11 5 30
followed by:
INITIATE
and the input weather data as presented for the first 25 days
in table 4. After the program has read the last data line, it will
come back and ask for an output file name
UNITi ?
Then type:
B:OUTPUT.FIL assuming a 2-drive machine; use
C:OUTPUT. FIL if hard disk is available.
The program will inform the user that it has finished the in-
put and initiation process:
INITIATION NOW COMPLETE. ENTER DYNAMIC
LOOP
and will write the results of the simulation at the fixed time
[17]
Table 4. Output Data Sent to Screen or Printer During Initiation
of the Model
From left to right, calendar day (SIMDAY), daily total solar radiation
(RADN), daily maximum air temperature (MAXTEM), daily minimum air
temperature (MINTEM), daily total rainfall (CMRAIN), daily total open
pan evaporation (PEVAP), daily maximum soil temperature (MAXSTM), 
daily
minimum soil temperature (MINSTM), month (MONTH), and day of 
the month
(DATE)
SIMDAY1 RADN MAXTEM MINTEM CMRAIN PEVAP MAXSTM MINSTM MONTH DATE
day J m-
2  
?C ?C m day-1 m day-
1  
oC ?C
150.0 0.20E+08 30.56 16.67 0.38 0.74 33.33 21.11 5 30
151.0 .27E+08 31.11 16.67 0.00 1.17 31.67 20.56 5 31
152.0 .27E+08 28.33 15.00 00 0 .84 33.89 21.11 6 1
153.0 .20E+08 25.56 11.67 0.00 .61 31.67 20.56 6 2
154.0 .28E+08 28.33 15.56 0.00 .69 35.00 21.11 6 3
155.0 .25E+08 31.11 17.78 .23 .76 35.56 23.33 6 4
156.0 .20E+08 28.89 16.67 0.00 .51 33.33 23.89 6 5
157.0 .16E+08 28.89 16.67 0.00 .41 32.78 23.89 6 6
158.0 .18E+08 27.78 18.33 1.22 .53 32.22 21.11 6 7
159.0 .54E+07 22.22 14.44 1.45 .23 24.44 20.00 6 8
160.0 .26E+08 26.67 15.00 00 0 .66 30.00 20.00 6 9
161.0 .22E+08 27.78 16.11 0.00 .58 30.00 20.00 6 10
162.0 .26E+08 27.78 15.00 0.00 .79 31.67 20.00 6 11
163.0 .27E+08 28.33 16.11 0.00 .84 33.33 21.11 6 12
164.0 .28E+08 28.33 17.22 0.00 .97 34.44 21.67 6 13
165.0 .28E+08 28.89 16.11 0.00 .94 36.11 22.78 6 14
166.0 .25E+08 30.00 13.33 0.00 .66 36.11 22.78 6 15
167.0 .24E+08 31.11 16.11 0.00 .66 36.11 23.33 6 16
168.0 .21E+08 32.22 19.44 0.00 .43 36.67 24.44 6 17
169.0 .16E+08 29.44 18.33 .58 .53 33.33 23.89 6 18
170.0 .15E+08 28.33 18.33 1.07 .61 30.56 22.78 6 19
171.0 .1OE+08 27.78 18.33 1.19 .36 27.78 21.67 6 20
172.0 .18E+08 27.78 19.44 0.00 .51 29.44 22.22 6 21
173.0 .12E+08 26.11 19.44 .03 .36 27.22 22.78 6 22
174.0 .17E+08 30.56 20.56 .05 .43 31.67 23.33 6 23
175.0 .10E+08 25.56 18.33 .03 .33 27.78 22.22 6 24
1
Definition and unit for each variable are given in Appendix D.
step interval read from unit 8 into this output file. For every
hour of simulation it will also print the information presented
in table 5 on the screen, to keep the user up to date with the
progress of the current simulation run. The output file, table
3, can be read after the simulation is finished, and can be split
into different data sets according to the output specification.
These data sets can then be plotted by the X-Y plotting rou-
tines, available on the micro-computer.
Without an 8087 coprocessor, it takes about 14 seconds to
simulate 1 hour of plant growth on an IBM-PC
3
. To speed up
the simulation process, longer time steps can be used or less
output can be generated. Another option is to use different
math coprocessors or another micro-computer.
DISCUSSION
An update of the model ROOTSIMU version 4.0 described
by Huck and Hillel (21) is presented. The major changes
made in the model are inclusion of input statements, which
read daily observed climatic data, and algorithms which cal-
culate instantaneous values from given daily totals. The shoot
was divided into a stem part and a leaf part and a new canopy-
[181
Table 5. Output Data Sent to Screen or Printer During Current
Simulation Run
From left to right, calendar day (JULIAN), shoot 
dry matter (SHOOTW),
root dry matter (ROOTW), leaf area index (LAI), 
root length (ROOTL),
photosynthetic rate (PHOTSN), canopy water potential (POTCR), and
transpiration rate (TRANSP)
JULIAN : day SHOOTW : kg m-
2  
ROOTW : kg m
2  
LAI m
2 
m
2
ROOTL : m m-
2  
PHOTSN : kg m-
2
s-1 POTCR m TRANSP: m s-1 1
JULIAN=150.00 SHOOTW= 0.01000 ROOTW= 0.00200 LAI= 0.225
ROOTL= 26.009 PHOTSN= 0.75E-18 POTCR= -2.00 TRANSP= 0.48E-10
JULIAN=150.04 SHOOTW= 0.01001 ROOTW= 0.00200 LAI 0.225
ROOTL= 25.993 PHOTSN= 0.75E-18 POTCR= -2.00 TRANSP= 0.49E-10
JULIAN=150.08 SHOOTW= 0.01002 ROOTW= 0.00200 LAI= 0.225
ROOTL= 25.976 PHOTSN= 0.75E-18 POTCR= -2.00 TRANSP= 0.50E-10
JULIAN=150.12 SHOOTW= 0.01002 ROOTW= 0.00200 LAI= 0.225
ROOTL= 25.959 PHOTSN= 0.75E-18 POTCR= -2.00 TRANSP= 0.52E-10
JULIAN=150.17 SHOOTW= 0.01003 ROOTW= 0.00200 LAI= 0.226
ROOTL= 25.941 PHOTSN= 0.75E-18 POTCR= -2.00 TRANSP= 0.53E-10
JULIAN=150.21 SHOOTW= 0.01004 ROOTW= 0.00199 LAI= 0.226
ROOTL= 25.923 PHOTSN= 0.75E-18 POTCR= -2.00 TRANSP= 0.54E-10
JULIAN=150.25 SHOOTW= 0.01004 ROOTW= 0.00199 LAI= 0.226
ROOTL= 25.906 PHOTSN= 0.17E-07 POTCR= -12.70 TRANSP= 0.22E-08
JULIAN=150.29 SHOOTW= 0.01005 ROOTW= 0.00199 LAI= 0.226
ROOTL= 25.901 PHOTSN= 0.21E-07 POTCR= -27.69 TRANSP= 0.49E-08
JULIAN=150.33 SHOOTW= 0.01006 ROOTW= 0.00199 LAI= 0.226
ROOTL= 25.912 PHOTSN= 0.23E-07 POTCR= -42.57 TRANSP= 0.76E-08
JULIAN=150.37 SHOOTW= 0.01007 ROOTW= 0.00200 LAI= 0.226
ROOTL= 25.943 PHOTSN= 0.24E-07 POTCR= -57.11 TRANSP= 0.98E-08
JULIAN=150.42 SHOOTW= 0.01008 ROOTW= 0.00200 LAI= 0.227
ROOTL= 25.989 PHOTSN= 0.24E-01 POTCR= -71.17 TRANSP= 0.llE-07
JULIAN=150.46 SHOOTW= 0.01009 ROOTW= 0.00200 LAI= 0.227
ROOTL= 26.053 PHOTSN= 0.24E-07 POTCR= -83.54 TRANSP= 0.12E-07
JULJAN=150.50 SHOOTW= 0.01010 ROOTW= 0.00201 LAI= 0.221
ROOTL= 26.137 PHOTSN= 0.24E-07 POTCR= -92.39 TRANSP= 0.13E-07
1
Units are given for information only and are not generated during
the actual simulation run.
[19]
photosynthesis section was added. The root-growth and
water-uptake sections were further refined and a section
which reduces root growth under severe soil impedance con-
ditions was added. Finally, an option was added to the model
to simulate plant and root growth under irrigated and nonir-
rigated conditions, corresponding to experimental conditions
at the Auburn rhizotron.
Detailed validation studies, using ROOTSIMU version 4.0
(CSMP-model) and 1981 experimental data, will be published
by Hoogenboom et al. (17). For examples presented in this
publication, 1983 weather data were used as input functions.
The model was run in background mode on a mainframe com-
puter. Although a large amount of CPU time was required,
several simultaneous runs, which were needed to calibrate
the model, could be executed at the same time. Trial runs on
a micro-computer took several hours of actual simulation
time. Depending on the resources available, the best perfor-
mance of the model will be obtained by using the CSMP or
ACSL version of the model on either a mainframe or mini-
computer.
In these trial simulation runs, 
4
c....opy was a critical value in
determining total growth. After a rain, upper layers of soil
rewet quickly, while water percolated slowly into deeper soil
layers until a new equilibrium water potential was estab-
lished. Plant water potential was high when many roots were
present in wet soil, but as soil water reserves diminished,
plant water stress increased. An increasing fraction of soluble
carbohydrates was used in the formation of new root tissue as
water was depleted from the soil. During the calibration runs
of the model, it was observed that under extreme drought
conditions plants lost turgor and finally died, usually from
carbohydrate starvation because CO
2 
exchange was blocked
when stomata could not open due to water stress.
CONCLUSIONS
Based on calibration runs with the model ROOTSIMU
version 4.0, it can be concluded that:
The approach used to handle climatic data provided good
algorithms to input real weather data into the model.
The infiltration procedure, together with the Darcian flow
equation, was successful in that the predicted below-ground
water regime compared reasonably well to experimentally
recorded values.
As with the Huck and Hillel (21) version, this model gave
plausible indicators of plant response to climatic variables
and selected soil variables.
The run time was not excessive on any large system. The
model can be run on a personal computer, but considerable
time is required.
The simulation languages CSMP and ACSL provided the
best languages for running the model.
[20]
BIBLIOGRAPHY
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4 
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(17) HOOGENBOOM, G., M. G. HUCK, AND C. M. PETERSON.
1986a. Comparisons Between Experimental Data and Predic-
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1986b. Root Growth Rate of Soybean as Affected by Water
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(21) AND D. HILLEL. 1983. A Model of Root
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(23) , C. M. PETERSON, G. HOOGENBOOM, AND C.
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the Soybean Canopy. Crop Sci. 12:180-183.
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assimilation Light Response Curves of Leaves: Some Exper-
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(27) MASON, W K., H. R. ROWSE, A. T. P BENNIE, T. C. KASPAR,
AND H. M. TAYLOR. 1982. Responses of Soybeans to Two Row
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(28) MITCHELL AND GAUTHIER, ASSOC. 1981. Advanced Continu-
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Manual. Mitchell and Gauthier, Assoc., Inc., Concord, Mass.
(29) MONTEITH, J. L. 1973. Principles of Environmental Physics.
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Bare Soil, and Grass. Proc. R. Soc. London, Ser. A, 193:120-
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H. VAN LAAR. 1974. Products, Requirements, and Efficiency
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45:339-377.
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A. S. HEAGLE, D. W. ISRAEL, J. M. SMITH, K. A. SURANO
AND J. E THOMAS. 1980. Field Studies of Plant Responses to
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sponse of Vegetation to Carbon Dioxide. No. 001, USDA and
USDOE, Washington, D.C.
(34) SHAW, R. H. AND D. R. LAING. 1966. Moisture Stress and
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[21]
(35) SHIBLES, R. M. AND C. R. WEBER. 1965. Leaf Area, Solar Ra-
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Crop Sci. 5:575-577.
(36) SPECKHART, E H. AND W. L. GREEN. 1976. A Guide to Using
C. S. M. P-the Continuous System Modeling Program. Pren-
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(40) , ET AL. 1978. Simulation of Assimilation,
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[221
APPENDIX A:
CSMP-LISTING OF SIMULATION MODEL
* *-CONTINUOUS SYSTEM MODELING PROGRAM** *
TITLE WATER UPTAKE AND ROOT GROWTH IN A HOMOGENEOUS SOIL PROFILE *
* NEW PHOTOSYNTHESIS RESPONSE AND ROOT GROWTH FUNGTIONS *
* WEATHER DATA :1981 - AUBURN RHIZOTRON *
* * VERSION 4.0 * *
* GERRIT HOOGENBOOM & M.G. HUGK; AUBURN UNIVERSITY,ALABAMA *
APRIL 1984
* AREA IS UNITY (M**2). UNITS SI (MKS).
*ORGANIG MATTER PRODUGTION NORMALIZED TO 1 KG/M**2/YEAR *
t WHIGH IS 10 GM/M**2/DAY OR 0.01 MG/M**2/SEG, ON AVERAGE
** SETTING UP ARRAY VARIABLES **
/ DIMENSION PTOTL(20)
* NOTE THAT PTOTL NOW IS EQUAL TO HPOT,AS OSMOTIC GONTRIBUTION NEGLEGTED
/ DIMENSION LINE(101), RK(20), DEPTH(20)
/ DATA IX/'*'/,IB/' '/,LINE(1)/'l'/
STORAGE RSRT(20), DIST(20), THETA(20), RRS(20), ARS(20)
STORAGE FLW(20), COND(20) , AVGOND(20) , POTRT(20)
STORAGE POTH(20), POTM(20), RSSL(20), Y(20), SGALE(20)
STORAGE TGOM(20), RRL(20), SMIN(20), SMAX(20), ITHETA(20)
STORAGE BIRTH(20), EXTENS(20), RTGRO(20), RTDTH(20)
STORAGE DAYS(13),POROS(20),BULKDS(20)
FIXED T, ISEED, DAYS, MONTH, I, J, IY, K, JDAY
FIXED NJ,NJJ,NNJ,LINE,IX,IB,JJ,KK,IFUN,RUNS
,to
IIf
INTITLE WATER UPPOLATION OF TEMPERATURE ALONG SINE PROFILE ( DE WIT ET AL.)
MARO TEMP = WAVE(JULIANHOURMNTBMXTBRISE)T
0%, WEATHER DATA 1981 AUBURN RHIZOTRN0
TIM = INSW(HOUR-14.,HOUR+0,HOUR-14.1
GERRITMAXT = AFGHOOEN(MXTB,(JULIAN-14/24.)) & M.G HUCK; AUB
APRMINT = AFGEN(MNTB,(JULIAN-RISE/24.))
VALAV= 0..5*(MAXT+MINT)
,to
VALAMP=0 UNIT 5*(MAXT-MINT)SI (MKS
TE ORGANIC MATTER PRODUCTION NORMALIZED TO 1UR-RISE)/(14.-RISE))
*TEMPERATURE DURING RISING OF THE SUN
WHICTEMPSH IS 10 M/M= VALAV+VALAMP*Y OR 001 OS(PI*TIM/(10.+RISE))
VARIBE
SDIMENSION 
J-
NOTE THAT PTOTL NOW IS EQUAL TO HPOT,AS OSMOTCCNRBTO ELCE
SDIMENSION LINE0101), 
SDATA IX/"F ,IB/
THETA(20),RS2) R(0
COM(20) RRL(20, SMIN(0), SMA(20), IHETA(20
[23]
TEMPERATURE DURING SETTING OF SUN
TEMP = INSW(AND(HOUR-RISE,14.-HOUR)-0.5,TEMPSS,TEMPSR)
ENDMAC
DAILY TOTALS (DE WIT ET AL.)
MACRO DTOT = DLYTOT(DTOTI,RATE)
DTOT1 = INTGRL(DTOTI,RATE)
DTOT = DTOT1-ZHOLD(IMPULS((AMAX1(DELT,60.)),86400.)*KEEP,DTOT1)
* THE ACCUMULATOR IS EMPTIED AFTER MIDNIGHT,
* SO CONTENTS ARE AVAILABLE FOR PRINTING
ENDMAC
MACRO MONTH, J = MTIME(JDAY)
MONTH = (JDAY/29) + 1
J = JDAY - DAYS(MONTH)
IF (J.GE.1) GO TO 775
MONTH = MONTH - 1
J = JDAY - DAYS(MONTH)
775 CONTINUE
TABLE DAYS(1-13)=0,31,59,90,120,151,181,212,243,273,304,334,365
* NOTE THAT THE NUMBER OF DAYS AT THE END OF EACH MONTH SHOWN ABOVE
* IS ONLY CORRECT FOR NON-LEAP YEARS. ADD 1 FEB-DEC FOR LEAP YEARS.
ENDMAC
SYSTEM GEN
SYSTEM NPOINT=6000
*DECK
TABLE SMAX(1-6) = .35 , 1.0E10 , .004 , 2.0,+0.3E-7, 5.0E2
TABLE SMIN(1-6) = .05 , -0.5 , 0.0 , -.1,-0.3E-7, 0.0
* SCALE FACTORS FOR VERTICAL GRADIENT PLOTS
$%^ % 0 0%* $%INITIAL SEGMENT 1 4 % I J%* **
INITIAL
ZYX = DEBUG(01,0.0)
LOAD FUNCTIONS FOR REAL WEATHER DATA
PROCEDURE MONTH,DAY,MAXTEM,MINTEM, CMRAIN,RADN,SIMDAY = AAA(TIME)
* XX = DEBUG(01,0.0)
* READ(11,511) ISHOOT,IROOT,IDAY,ICHO
* READ(11,512) (ITHETA(I),I=1,11)
*READ(11,512) (RRL(I),I=1,10)
* WRITE(06,511) ISHOOT,IROOT,IDAY,IGHO
* WRITE(06,512) (ITHETA(I) ,I=1 ,11)
* WRITE(06,512) (RRL(I),I=1,10)
511 FORMAT(08G10.4)
512 FORMAT(11G07.2)
JULIAN = START + TIME / 86400.
SIMDAY = JULIAN
[24]
1853 FORMAT(/,' INITIATE ',/,4X,'SIMDAY',8X,'RADN',7X,'MAXTEM')
* WRITE(6,1853)
IF (START.GT.400) GO TO 500
FUNCTION MAXTMP
CALL FGLOAD(MAXTMP,.,19.,1)
DO 01 K=1,365
READ(4,91,END=301) RADN, MAXTEM, MINTEM, CMRAIN, PEVAP ,...
MAXSTM,MINSTM,SIMDAY
* READ IN HISTORICAL WEATHER RECORDS OF INTEREST
91 FORMAT(F3.0,1X,F5.1,F6.1,F6.2,F7.3,F3.0,F3.0,T76, F3.0)
JULIAN = SIMDAY
JDAY = JULIAN
MONTH, J = MTIME(JDAY)
IF (SIMDAY.GT.400) GO TO 101
* WRITE(6,92) SIMDAY, RADN, MAXTEM, MINTEM, CMRAIN, PEVAP,MONTH,...
* MAXSTM,MINSTM,J 
, JDAY
92 FORMAT(11G10.4)
101 MAXTEM = ( MAXTEM - 32. ) * 5. / 9.
CALL FGLOAD(MAXTMP,JULIAN,MAXTEM,1)
* LOADING INPUT FILES INTO APPROPRIATE FUNCTIONS FOR INTERPOLATION
01 CONTINUE
301 CALL FGLOAD(MAXTMP,400.,MAXTEM,1)
* GO TO 500
REWIND 4
FUNCTION MINTMP
CALL FGLOAD(MINTMP,0.,15.,1)
DO 11 K=1,365
READ(4,91,END=302) RADN, MAXTEM, MINTEM, CMRAIN, PEVAP ,...
MAXSTM,MINSTM,SIMDAY
* READ HISTORICAL WEATHER RECORDS AGAIN (FGLOAD CAN LOAD ONLY ONE
FUNCTION AT A TIME).
JDAY = SIMDAY
JULIAN = JDAY
MINTEM = ( MINTEM - 32. ) * 5 / 9.
IF (SIMDAY.GT.200) GO TO 1011
* WRITE(6,92) SIMDAY, 
MINTEM,
1011 CALL FGLOAD(MINTMP,JULIAN,MINTEM,1)
* LOADING OF MINTEM VALUES INTO FUNCTION MINTMP
11 CONTINUE
302 CALL FGLOAD(MINTMP,400.,MINTEM,1)
* GO TO 500
88 REWIND 4
JDAY, JULIAN
FUNCTION RADFCN
CALL FGLOAD(RADFCN,0.,100.,1)
DO 12 K=1,365
READ(4,91,END=303) RADN, MAXTEM, MINTEM, CMRAIN, PEVAP ,...
MAXSTM,MINSTM,SIMDAY
* READ HISTORICAL WEATHER RECORDS YET ANOTHER TIME
JDAY = SIMDAY
JULIAN = JDAY
RADN = RADN * 4.2 * 10000
IF (SIMDAY.GT.365) GO TO 1012
* WRITE(6,92) SIMDAY, RADN, JULIAN, JDAY
1012 CALL FGLOAD(RADFCN,JULIAN,RADN,1)
[25]
* LOADING OF RADN VALUES 
INTO FUNCTION RADFCN
12 CONTINUE
303 CALL FGLOAD(RADFCN,400.,RADN ,1)
* GO TO 500
89 REWIND 4
FUNCTION RNFALL
CALL FGLOAD(RNFALL,0.,0.1,1)
DO 13 K=1,365
READ(4,91,END=304) RADN, MAXTEM, MINTEM, CMRAIN, PEVAP
MAXSTM,MINSTM,SIMDAY
* READ HISTORICAL WEATHER RECORDS YET ANOTHER TIME
CMRAIN = CMRAIN * 2.54
* CMRAIN = 0.0
JDAY = SIMDAY
JULIAN = JDAY
IF (SIMDAY.GT.200) GO TO 1013
WRITE(6,92) SIMDAY, CMRAIN, JDAY
1013 CALL FGLOAD(RNFALL,JULIAN,CMRAIN,1)
* LOADING OF RADN VALUES INTO FUNCTION RADFCN
13 CONTINUE
304 CALL FGLOAD(RNFALL,400.,CMRAIN,1)
500 CONTINUE
90 REWIND 4
FUNCTION PEV
CALL FGLOAD(PEV,0.,O.1,1)
DO 14 K=1,365
READ(4,91,END=305) RADN, MAXTEM, MINTEM, CMRAIN, PEVAP
MAXSTM,MINSTM,SIMDAY
* READ HISTORICAL WEATHER RECORDS YET ANOTHER TIME
PEVAP = PEVAP * 2.54
JDAY = SIMDAY
JULIAN = JDAY
IF (SIMDAY.GT.200) CO TO 1014
* WRITE(6,92) SIMDAY, PEVAP, JDAY
1014 CALL FGLOAD(PEV,JULIAN,PEVAP,1)
* LOADING OF PEVAP VALUES 
INTO FUNCTION PEV
14 CONTINUE
305 CALL FGLOAD(PEV,400.,PEVAP,1)
501 CONTINUE
191 REWIND 4
FUNCTION MXSTMP
CALL FGLOAD(MXSTMP,0.,19.,1)
DO 1115 K=1,365
READ(4,91,END=306) RADN, MAXTEM, MINTEM, CMRAIN, PEVAP ,...
MAXSTM,MINSTM,SIMDAY
* READ IN HISTORICAL WEATHER RECORDS OF INTEREST
JULIAN = SIMDAY
JDAY = JULIAN
MONTH, J = MTIME(JDAY)
MAXSTM = ( MAXSTM - 32. ) * 5. / 9.
IF (SIMDAY.CT.200) GO TO 1015
* WRITE(6,92) SIMDAY, RADN, MAXTEM, MINTEM, CMRAIN, PEVAP,MONTH,...
* MAXSTM,MINSTM,J , JDAY
1015 CALL FGLOAD(MXSTMP,JULIAN,MAXSTM,1)
[26]
LOADING INPUT FILES INTO APPROPRIATE FUNCTIONS FOR INTERPOLATION
1115 CONTINUE
306 CALL FCLOAD(MXSTMP,400.,MAXSTM,1)
GO TO 500
192 REWIND 4
FUNCTION MNSTMP
CALL FGLOAD(MNSTMP,0.,15.,1)
DO 16 K=19365
READ(4,91,END=307) RADN, MAXTEM, MINTEM, CMRAIN, PEVAP
MAXSTM,MINSTM, SIMDAY
*FINAL READING OF HISTORICAL WEATHER RECORDS AGAIN
JDAY = SIMDAY
JULIAN = JDAY
MINSTM = ( MINSTM - 32. )*5. /9.
IF (SIMDAY.GT.200) GO TO 1017
WRITE(6,92) SIMDAY, 
MINTEM,
1017 CALL FGLOAD(MNSTMP,JULIAN,MINSTM,1)
*% LOADING OF MINSTM VALUES INTO FUNCTION 
MNSTMP
16 CONTINUE
307 CALL FGLOAD(MNSTMP,400. ,MINSTM,1)
* GO TO 500
193 REWIND 4
JDAY, JULIAN
JJ j J
T =MONTH
TT=T
11 DOUBLE LETTERS ARE REAL NUMBER REPRESENTATION FOR OUTPUT 
VARIABLES.
% ZY DEBUG(01,0.0)
ENDPRO
PARAM PI = 3.14159
PARAM ECON= 2.71828
RAD =P1/180.
SSTANDARD MATHEMATICAL CONSTANTS
LOCATION TO BE SIMULATED
PARAM LAT= 32.5
CSLT = COS(RAD*LAT)
COSINE LATITUDE
SNLT =SIN(RAD*LAT)
SINE LATITUDE
- AUBURN ALA., USA.
[271
** * * * * * * * * * * RUN CONTROL * * * * * * * * * * * * * * * * * *
TIMER FINTIM= 4320000000., OUTDEL =03600.,PRDEL=3600.,...
DELT=03600.,DELMIN=1.00,DELMAX=3600.
JULIAN = START + TIME/86400.
* BASIC TIMER UNITS ARE SECONDS. SEE TIME DEFINITIONS IN DYNAMIC SECT.
OUTF = 3.024E05
OUTPUT FUNCTION FOR VERTICAL GRADIENT PLOTS MADE DURING EXECUTION --
* --INITIAL FREQUENCY FOR VERTICAL GRADIENT PLOTS IS INCREMENTED LATER.
*FINISH HOURS=2160.,POTCR= 
-300., SOLCHO = +.0E-07, 
SHOOTW=0.0001, ...
FINISH HOURS=2400.,POTCR= -460., SOLCHO = +1.0E-07, SHOOTW=0.0001, ...
TOPGRO = -1.OE-10, TOTRG = -1.OE-18 ,JULIAN=365.
* THE SIMULATION WILL TERMINATE WHEN THE PLANT WATER POTENTIAL DROPS
* BELOW -460 METERS WATER POTENTIAL (OR -4.5 MPA) (BOYER, 1970),
* OR WHENEVER SOLUBLE CARBOHYDRATE IS EXPENDED (NO FOOD IN STORAGE).
MTH = MONTH - 0.5 + ((DAY/30))
* REAL-NUMBER REPRESENTATION OF MONTH, FOR INDEXING TABULAR FUNCTIONS.
*METHOD RECT
METHOD RKS
RELERR SOLCHO = 1.0E-02
ABSERR SOLCHO = 1.0OE-02
RELERR POTCRD = 1.0OE-01
ABSERR POTCRD = 1.0OE-01
ABSERR LSNHS = 0.1
RELERR LSNHS = 0.1
RELERR SHOOTW = 1.OE-04
ABSERR SHOOTW = 1.0OE-04
RELERR CUMRAD = 1.OE-03
ABSERR CUMRAD = 1.0OE-03
* SPECIFICATION OF CONVERGENCE CRITERIA FOR VARIABLE TIME-STEP INTGRLS
RUNS = 0
FLPFLP = -1.0
PARAMETER ERROR = 0.01
PARAMETER CF = 0.10
* CORRECTION FACTOR AND ERROR PARAMETERS FOR ITERATIVE LOOP
* ** INITIATION OF PLANT-GROWTH PARAMETERS
PARAM IPER = 0.03
ICHO = (ISHOOT + IROOT) * IPER / ( 1. - IPER )
* INITIAL CARBOHYDRATES (KG/M**2), AS DECIMAL FRACTION OF TOTAL WGT.
PARAM ISHOOT = 1O.0E-03
PARAM IROOT = 02.00E-03
* INITIAL SHOOT AND ROOT WEIGHTS, RESPECTIVELY (KG/M**2)
DRYWT = ISHOOT + IROOT
STEMW = STWTR * ISHOOT
LEAFW = ISHOOT - STEMW
LAI = LEAFW * LEAFTH
IRTL = IROOT * LNGFAC
[28]1
* METERS OF ROOT/SQUARE 
METER GROUND AREA AT INITIATION
PARAM RTDWPC = 10.
* PERCENTAGE DRY MATTER OF ROOTS
PARAM LNGFAC = 13000.0
* LENGTH FACTOR, AS METERS OF ROOT PER KG ROOT WEIGHT
* (A FACTOR OF 1000 CORRESPONDS TO ABOUT 1 MM ROOT DIAMETER)
LEAF AREA INDEX -- AREA OF LEAF SURFACE/UNIT LAND AREA
TABLE RRL(1-10) = 0.54, 0.38, 0.08, 0.00, 0.0,...
0.0 , 0.0, 0.0, 0.0, 0.0
*TABLE RRL(1-10) = 2.7E-01, 2.5E-01, 2.4E-01, 2.1E-01, 0.03, ...
* .00, 0.0, 0.0, 0.0, 0.0
* RELATIVE ROOT LENGTH (AS FRACTION OF TOTAL)
C1=2
C2=1
01=2
02=1
* ** INITIATION OF WATER-BALANCE 
PARAMETERS
TABLE ITHETA(1-11) = 0.200, 0.200, 0.200, 0.200, 0.200,
0.200, 0.200, 0.200, 0.200, 0.230,0.300
INITIAL SOIL WATER CONTENT (VOLUME FRACTION)
* (INITIATED TO VALUES FOUND AFTER 12 DAYS OF DRAINING FROM
* SATURATION AT 20% WATER IN ALL LAYERS)
PARAM STHETA = 0.36
SATCON = 5.00E-03 / 100
*PARAM SATCON = 10.00E-03 / 100
* SATURATED CONDUCTIVITY, AS M/SEC
ETA = 2.0 + 3.0 * ZLAM
PARAM ZLAM = 0.64762
* Z(LAMBDA), AFTER LALIBERTE, BROOKS, & COREY
PARAM ALPHA = 0.24890
PARAM NU = 1.21555
MU = 1 - ( 1 / NU )
* A,N,M FOR HYDRAULIC CONDUCTIVITY CALCULATIONS AFTER VAN GENUCHTEN,1978
PARAM PARTDS = 2.59
* PARTICLE DENSITY
FUNCTION BULKF = ((0.0,1.52),(1.0,1.52),(2.0,1.52))
* BULKDENSITY AS A FUNCTION 
OF DEPTH
TABLE TCOM(1-20) = .10, 2 * .15 ,17 * .20
* THICKNESS OF EACH VERTICAL LAYER (COMPARTMENT), METERS
NOSORT
**PROCEDURE DEPTH,DIST,PRTL,RSRT,IVOLW = INTLZ(TCOM,RRL)
* ZYX = DEBUG(01,0.0)
PARAM NJ = 10
NJJ = NJ+1
* ONE MORE THAN THE NUMBER OF LAYERS IN THE SOIL PROFILE (NJ)
NNJ = NJ - 1
* ONE LESS THAN THE NUMBER OF LAYERS IN THE SOIL PROFILE (NJ)
DO 15 I = 1,NJJ
15 FLW(I) = 0.0
* FLOW OF WATER PAST BOTTOM OF EACH LAYER, INITIATED TO 0.0
[29]
* THE NUMBER OF LAYERS(J) IN THE SOIL PROFILE
DEPTH(1) = .5*(TCOM(1))
DIST(1) = DEPTH(1)
IVOLW(1) = ITHETA(1)*TCOM(1)*1.0
DO 20 I = 2,NJJ
DIST(I) = .5*(TCOM(I-1)+TCOM(I))
DEPTH(I) = DEPTH(I-1) + DIST(I)
IVOLW(I) = ITHETA(I)*TCOM(I)*1.0
* INITIAL VOLUME OF WATER IN EACH SOIL LAYER
20 CONTINUE
853 FORMAT(/,' INITIATE ',/,9X,'I',3X,'IPRTL',5X,'RSRT',8X,'IVOLW')
WRITE(6,853)
* 853 FORMAT(/, ' INITIATION ', , 8X, 'I', 
5X, 'IPRTL', 5X, ...
* 'RSAT', 6X, 'IVOLW', 5X, 'TCOM', 4X, 'ITHETA', 
5X, 'IRTL',
* 6X, 'RRL', 5X, 'DEPTH', /)
DO 30 I = 1,NJ
IPRTL(I) = IRTL * RRL(I)
* PARTIAL ROOT LENGTH, AT INITIATION
IRTWT(I) = IPRTL(I) / LNGFAC
* ROOT WEIGHT, AT INITIATION
IRTVL(I) = IRTWT(I) * 100. / (RTDWPC*1000)
* ROOT VOLUME, AT INITIATION
RRS(I) = URRS / (IPRTL(I) +NOT(IPRTL(I))*1.OE-10)
* RADIAL RESISTANCE TO WATER 
FLOW IN THE ROOT
ARS(I) = UARS * DEPTH(I) / (IPRTL(I) + NOT(IPRTL(I))*1.E-10)
* AXIAL RESISTANCE -- ALONG THE XYLEM TRANSPORT SYSTEM
RSRT(I) = RRS(I) + ARS(I)
* RESISTANCE OF THE ROOTS
WRITE(6,454) I,IPRTL(I),RSRT(I),IVOLW(I),TCOM(I),ITHETA(I),...
IRTL, RRL(I), DEPTH(I)
454 FORMAT(3G10.3, 3F10.5, G10.3, 2F10.5, 3G10.3)
30 CONTINUE
**ENDPRO
POTCR = -20.000
* POTENTIAL OF THE CROWN (SHOOT), 
INITIATED BELOW DRIEST SOIL 
LAYER
* (-20 METERS 
= -0.2 MPA)
FUNCTION SUTB = (0.00,60.),(0.0674,40.81),(0.0940,21.21),...
(0.1119,15.27),(0.1263,7.325),(0.1363,4.11),(0.1531,2.01),...
(0.1705,0.99),(0.2063,0.425),(0.2461,0.264),...
(0.36,0.0),(0.42,0.0),(0.50,0.0)
* IN - SITU RHIZOTRON DATA 1982
NOSORT
DO 10 I = 2,101
10 LINE(I) = IB
* INITIATES PRINT-LINE FOR VERTICAL PLOTS TO BLANK CHARACTER-STRING
ZZZ = DEBUG(01,0.0)
[301
** * * * * * * * * 
* DYNAMIC SEGMENT
DYNAMIC
f* YYY 
=DEBUG(100,1359000.)
f* ZZ 
= DEBUG(01,86400.)
** 
** TIME CALCULATIONS 
**
PARAM START = 150.
* BEGINNING DATE FOR THIS SIMULATION RUN
JULIAN = START + TIME/86400.
DAY = JULIAN
* JULIAN DATE OF SIMULATION
JDAY = JULIAN
* INTEGER REPRESENTATION OF JULIAN DAY, FOR INPUT TO MTIME
PROCEDURE MONTH, J = AAA(JDAY)
MONTH, J = MTIME(JDAY)
ENDPRO
T = MONTH
TT = T
* INTEGER AND REAL-NUMBER REPRESENTATIONS, RESPECTIVELY.
MTH = MONTH - 0.5 + ((AGE/30))
* REAL-NUMBER REPRESENTATION OF MONTH, FOR INDEXING AND OUTPUT
JJ = J
* CALENDAR DAY OF THE MONTH
AGE = HOURS / 24.00
* DAYS OF SIMULATION (CUMULATIVE, SINCE BEGINNING OF 
RUN).
HOURS = TIME/3600.0
* CUMULATIVE HOURS OF SIMULATION TIME
HOUR = AMOD(HOURS,24.0)
* CLOCK TIME, IN HOURS
RUN = RUNS
* CREATES A REAL-NUMBER COUNTING VARIABLE FOR PRINTER OUTPUT
* DIRECTION OF THE SUN
DEC = -23.4*COS(2.*PI*(JULIAN+10.)/365.)
* DECLINATION OF THE SUN
SNDC = SIN(RAD*DEC)
* SINE DECLINATION
CSDC = COS(RAD*DEC)
* COSINE DECLINATION
SNHSS=SNLT*SNDC+CSLT*CSDC*COS(PI*(HOUR+12.)/12.)
* SINE OF THE HEIGHT OF THE SUN
LSNHS=INTGRL(-0.5,(SNHSS-LSNHS)/DELT)
* SUN HEIGHT AT LAST TIME STEP
RISE = ZHOLD(AND(SNHSS,-LSNHS)-0.5,HOUR-SNHSS*DELT/
((NOT(SNHSS-LSNHS)+SNHSS-LSNHS)*3600.)-RISEI)+RISEI
* TIME OF SUN RISE TODAY, IN HOURS, ESTIMATED FOR TOMORROW
INCON RISEI = 4.8
[31]
** ESTIMATION OF TEMPERATURE EFFECTS **
TMPFCS = 10.0 ** ((TEMP-REFT) * 0.030103)
TMPFCR = 10.0 ** ((STEMP-REFTS) * 0.030103)
BIOLOGICAL Q-10 -- DOUBLING REACTION RATE AT EACH 10 DEGREE TEMP CHNG
TEMP = WAVE(JULIAN,HOUR,MINTMP,MAXTMP,RISE)
* AIR TEMPERATURE, AS DEGREES C.
REFT = 25.
AVAT = (MAXTEM + MINTEM) * 0.500
* AVERAGE AIR TEMPERATURE, FROM DAILY MEASUREMENT DATA
MAXTEM = AFGEN(MAXTMP,JULIAN-(14./24.))
MINTEM = AFGEN(MINTMP,JULIAN-(RISE/24.))
* LINEAR INTERPOLATION FROM INPUT DATA-FILE
RANGE = (MAXTEM - MINTEM) * 0.500
* AIR TEMPERATURE, AS DEGREES C.
STEMP = WAVE((JULIAN-0.16),(HOUR-4.),MNSTMP,MXSTMP,RISE)
REFTS = 25.
AVST = (MAXSTM + MINSTM) * 0.500
* AVERAGE SOIL TEMPERATURE, FROM DAILY MEASUREMENT DATA
MAXSTM = AFGEN(MXSTMP,JULIAN-(14.+4.)/24.)
MINSTM = AFGEN(MNSTMP,JULIAN-(RISE+4.)/24.)
* LINEAR INTERPOLATION FROM INPUT DATA-FILE
RANGES = (MAXSTM - MINSTM) * 0.500
* AMPLITUDE OF DAILY TEMPERATURE OSCILLATIONS
PARAM DELAY = 21600.
* DELAY FUNCTION, BASED UPON SOIL HEAT CAPACITY (HALF-TIME FOR
* EQUILIBRATION, IN RECIPROCAL SECONDS).
? ** RESERVE LEVELS 
AND TISSUE GROWTH
RESL = SOLCHO / (SOLCHO + ROOTW + SHOOTW)
RESERVE LEVEL, % FREE CARBOHYDRATE IN TISSUES
SOLCHO = INTGRL(ICHO, (PHOTSN * PHTCAR - GROWTH - RESP) )
PHTCAR = 30. / 44.
SSOLUBLE CARBOHYDRATES (FREELY MOBILE, AS METABOLIC RESERVES)
S (KG/SQUARE METER)
GROWTH = TOPGRO + TOTRG
? TOTAL GROWTH OF BOTH SHOOT 
AND ROOT SYSTEM
** ESTIMATION OF RADIATION INTENSITY **
CUMRAD = INTGRL(0.,RADN/86400.)
DAYRAD = (1-IMPULS(0.,86400.))*INTGRL(0.,RADN/86400.)
* CUMULATIVE TOTAL RADIATION RECEIVED--COMPARE WITH INPUT VALUES.
RADN = AMAX1(0.0, SIN(2*PI * (DAY - 0.250))) * MAXRAD * 3.0
* RADIATION INTENSITY (INSTANTANEOUS VALUE)
* FACTOR OF 3.0 PUTS ABSOLUTE VALUE ON SCALE WITH RIGHT UNITS
MAXRAD = AFGEN(RADFCN,JULIAN)/86400.
[321
**
RADIATION INTENSITY, INTERPOLATED FROM INPUT FILE
SNHS = AMAX1(0.,SNHSS)
HSUN = ATAN(SNHS/SQRT(1.-SNHS*SNHS))/RAD
DIFOV = AFGEN(DFOVTBHSUN)
FUNCTION DFOVTB = (0.,o.),(5.,6.),(15.,26.),9(25.45.),(35.,64.),...
(45,180. ),(55,994),(65.,105. ),(75.,112.)(9.,116)
DIFFUSE OVERCAST VISIBLE
DIFON = 0,7 * DIFOV
DIFFUSE OVERCAST INFRARED
DIFCL = AFGEN(DFCLTBHSUN)
FUNCTION DFCLTB = (o.,o.),(s.,29.),(5. ,42.),(25.,49.),(35. 
56.),...
(45.,64. ),(55.68. ),(65.,71.),(75.,75.),(90 77.)
DIFFUSE CLEAR
SUNDCL = AFCEN(SUNTB,HSUN)
FUNCTION SUNTB = (o.,o.),(5.,o.),(l5.,88.),(25.,175.),(35.,262*),...
(45o,336. 1(55.,402.),(65.,452.),(75. 483.),(90. 
504.)
DIRECT CLEAR
CRC = (SUNDCL+DIFCL)*2.
.f% CURRENT RADIATION CLEAR, ALL WAVELENGTHS
CRO DIFOV + DIFON
CURRENT RADIATION, OVERCAST
DRC = DLYTOT(DRCI,CRC)
DRO = DLYTOT(DROI,CRO)
INCON DROI = 6.6E6
INCON DRCI = 3.5E7
DRCP = ZHOLD(IMPULS(0.,86400.),DRC)
DROP = ZHOLD(IMPULS(0.,86400.),DRO)
DTRR=AFGEN(RADFCN,(JULIAN-0.0))
DTR = ZHOLD(IMPULS(0. ,86400. )*KEEPDTRR)
FCL = (DTR - DROP)/(NOT(DRCP-DROP)+DRCP-DROP)
FOV = 1. - FCL
LFOV = LIMIT(0.,1.,FOV)
LFCL = 1. - LFOV
RADIAT = LFCL * CRC + LFOV * CR0
DRAD =DLYTOT(DRADI,RADIAT)
INCON DRADI 1 .E-10
PHOTOSYNTHETIC ACTIVITY *
*PARAM MXPHOT= 0.6944E-6
PARAM MXPHOT = 08200E-6
*%' MAXIMUM PHOTOSYNTHETIC RATE -
25 MC C02 DM-2 (LEAF) H-1
PARAM DKPHOT = 0.
* NETT ASSIMIL ArnTTIO KNTHE VnDRK- DARK RESPIR)TDArTIONTOF %'rPTLANVS
[331
* TOTAL LEAF AREA IN THE SHADE
XOVC = RADOPH * EFF / ( MXPHOT * LAI )
POVC = XOVC / ( XOVC + 1. )
PHOTD = LAI * MXPHOT * POVC
SMAXIMUM CANOPY PHOTOSYNTHESIS UNDER AN OVERCAST SKY
XS = ALOG ( 1+(0.45 * EFF*RADCPH/(AMAX1(SLLA,0.0001)*MXPHOT)))
PS = XS / ( 1 + XS )
PHOTS = SLLA * MXPHOT * PS
* MAXIMUM CANOPY PHOTOSYNTHESIS UNDER A CLEAR 
SKY FOR SUNLIT LEAFAREA
XSH = ALOC( 1+(0,55 * EFF * RADCPH/(AMAX1(DLLA,0.0001)*MXPHOT)))
PSH = XSH / ( 1 + XSH )
PHOTSH = DLLA * MXPHOT PSH
* MAXIMUM CANOPY PHOTOSYNTHESIS UNDER A CLEAR SKY FOR 
SHADED LEAFAREA
PROCEDURE PHOTC,PHOTSN,PHOTSM=PROCPH(PHOTS,PHOTSH,PHOTD,WATRST,TMPFCS)
PHOTC = PHOTS + PHOTSH
IF ( LAI .GT. 03) GO TO 31
IF ( RADIAT .EQ. O ) CO TO 31
FINT = ( 1. - EXP(-0.8*LAI))
C1 = FINT * PHOTC
C2 = LAI * MXPHOT
01 = FINT * PHOTD
02 = C2
IF ( C1 .GT. C2 ) GO TO 32
CO = Cl
C1 = C2
C2 = CO
32 CONTINUE
PHOTC = C2 * ( 1. - EXP ( - C1 / (NOT(C2)+C2) ))
IF ( 01 .GT. 02 ) GO TO 33
00 = 01
01 = 02
02 = 00
33 CONTINUE
PHOTD = 02 * ( 1. - EXP ( - 01 / (NOT(02)+02) ))
31 CONTINUE
PHOTSN = WATRST * ( PHOTC * LFCL + PHOTD * LFOV)
PHOTSM = ( 1.- IMPULS(1800.,86400.))*AMAX1(PHOTSN,PHOTSM)
* PHOTOSYNTHETIC RATE (NET CARBON FIXATION, KG/SQUARE METER/SECOND
ENDPRO
ROOT AND SHOOT RESPIRATION
RESP = RESPSH + RESPRT
TOTAL RESPIRATION, INCLUDING BOTH SHOOT AND ROOT SYSTEM
RESPSH = SHMRES + SHCRES
*RATE OF SHOOT RESPIRATION (KC/SQ METER/SEC)
* (SUM OF GROWTH RESPIRATION AND MAINTENANCE RESPIRATION)
SHMRES = SHOOTW * TMPFCS * RSPFAC
CSTMRS = INTCRL( 0.0,SHMRES)
k SHOOT MAINTENANCE RESPIRATION
PARAM RSPFAC = 1.OE-07
*RESPIRATION FACTOR, CONVERTING UNITS AND PROPORTIONING
SHGRES = TOPGRO * CONVRT
[34]
* SHOOT GROWTH RESPIRATION
PARAM CONVRT = 0.30
* CONVERSION EFFICIENCY (WEIGHT OF TISSUE PRODUCED PER 
GRAM INPUT
* (INCLUDES RESPIRATION FOR TRANSPORT AND CHEMICAL CONVERSIONS)
RESPRT = RTMRES + RTGRES
* RESPIRATION 
OF ROOT SYSTEM
RTMRES = ROOTW * RSPFAC * TMPFCR
CRTMRS = INTGRL(0.0,RTMRES)
* ROOT MAINTENANCE RESPIRATION
RTGRES = TOTRG*CONVRT
* ROOT GROWTH RESPIRATION, INCLUDING CHEMICAL CONVERSION AND TRANSPORT
* ** GROWTH AND DEATH OF SHOOT TISSUE **
SHOOTW = INTGRL(ISHOOT, (TOPGRO - SHOOTD))
* WEIGHT OF LIVING SHOOT TISSUE (KG/SQ METER)
TOPGRO = TMPFCS * GROFAC * SOLCHO * FRAC
TOPGRO = TMPFCS * GROFAC * SOLCHO * FRG
* RATE AS (KG/SQ METER/SEC) OF SHOOT (STEMS, LEAVES, AND FRUIT)
* FRAC = AFGEN(FRACTB,POTCR)
FRAC = AFGEN(FRACTB,POTCRE)
* FRACTIONAL GROWTH, AS PERCENT OF CARBON GOING INTO THE SHOOT
POTCRE = AMIN1(POTCR, POTCRD)
* EFFECTIVE CANOPY WATER POTENTIAL
POTCRD = INTGRL(10.,(POTCR - POTCRD)/DELAY)
* DELAYED CANOPY 
WATER POTENTIAL
*PARAM DELAY 
= (21600., 
1800.)
PARAM DELAY = 21600.
* DELAY TIME FOR 
COMPUTING OF POTCRD, 
IN SECONDS
PARAM FRG = 0.666
*PARAM FRG = 
(0.0, 1.0, 0.666)
* FRACTION OF CARBOHYDRATES 
GOING TOWARD SUPPORT OF 
SHOOT GROWTH
FUNCTION FRACTB = -500.,.05, -200.,.20, -050.,.65, -05.,.90, ...
100.,.90
* UNITS = %, AS A FUNCTION OF CANOPY WATER POTENTIAL, POTCR
SHOOTD = LEAFW * TMPFCS * DTHBGN * AGING
* SHOOTD = SHOOTW * TMPFCS * DTHBGN * AGING
* SHOOT DEATH RATE (PRINCIPALLY LEAF-DROP DUE TO AGE AND WATER STRESS)
DTHBGN = AFGEN(DTBL, LAI)
* LEAVES BEGIN DYING AS LAI INCREASES ABOVE 2, DUE TO SELF-SHADING
FUNCTION DTBL = 0.0,0.0, 2.0,0.03, 5.0,0.33, 07.0,0.97,10.,1.00,25.,1.0
AGING = AGFAC * (AGE/30.)
*PARAM AGFAC = 3.0E-7
PARAM AGFAC = 3.0E-07
DRYWT = SHOOTW + ROOTW
STEMW = STWTR * SHOOTW
LEAFW = SHOOTW - STEMW
PARAM STWTR = 0.25
LAI = LEAFW * LEAFTH
[35]
* LEAF AREA INDEX, DIMENSIONLESS (AREA 
OF LEAF SURFACE/UNIT LAND AREA)
*PARAM LEAFTH 
=(2.5,5.0)
*PARAM LEAFTH 
= 4.0
PARAM LEAFTH = 30.
* ROGERS 
ET AL., 1982
* LEAF THICKNESS -- SQ. METERS LEAF AREA/SQ. METER SOIL, FOR EACH
* KG. SHOOT 
WGT ON THE SAME 
LAND AREA
* ** GROWTH 
AND DEATH OF AGGREGATED ROOT 
SYSTEM **
ROOTW = INTGRL(IROOT,(TOTRG-ROOTDY))
* WEIGHT OF LIVE ROOT TISSUE(ALL SOIL LAYERS)
ROOTL = ROOTW * LNGFAC
* LENGTH OF LIVE ROOT TISSUE(ALL SOIL LAYERS)
TOTRG = (1.0 - FRAC) * SOLCHO * GROFAC * TMPFCR
* TOTRG = (1.0 -
FRG) * SOLCHO * GROFAC 
* TMPFCR
* TOTAL ROOT GROWTH, 
SUM OF ROOT WEIGHT 
IN ALL SOIL LAYERS
PARAM GROFAC = 1.OE-05
* RELATIVE CONSUMPTION 
RATE FOR RESERVES -- 
AFTER DE WIT:
* (GROWTH FACTOR, CONVERTING SOLUBLE CARBOHYDRATE TO TISSUE BIOMASS)
ROOTDY = ROOTW / RESL* DTHFAC * TMPFCR
* RATE OF DYING FOR TOTAL ROOT SYSTEM -- MODULATED IN SUMMATION OF
* DEATH RATES FOR ROOTS IN EACH SOIL LAYER IN A LATER SECTION.
* INVERSELY PROPORTIONAL TO CARBOHYDRATE RESERVES--DYING OFF WHEN HUNGRY
* (RATE EXPRESSED AS KG ROOTS/SQUARE METER/SECOND -- WHOLE PLANT)
PARAM DTHFAC = 1.OE-08
*PARAM DTHFAC = (1.0E-07, 1.OE-09, 1.0E-05)
* FACTOR TO SCALE ROOT DEATH RATE
** TRANSPIRATION 
**
TRANSP = 1.0 * WATRST * PET * LAIFAC
* TRANSPIRATION LOSSES, AS METER/SECOND
WATRST = AFGEN(TRNTBL,POTCR)
* WATER STRESS IN PLANT TISSUE
FUNCTION TRNTBL = -500.,.05, -245.,.05,-163.,0.50,-112.,0.95,0.,1.0
* TRANSPIRATION TABLE FOR SOYBEAN 
( BOYER, 1970)
*FUNCTION TRNTBL = -500.,.05, -200.,.05, -010.,0.95, 
0.,1.0, 100.,1.0
* TRANSPIRATION TABLE FOR SUCCULENT 
CROPS SUCH AS MAIZE
*FUNCTION TRNTBL = -500.,0., -400.,0.02, 
-300.,0.06, ...
* -150.,0.75, -50.,0.96, 0.,1.00, 
+200.,1.00
* TRANSPIRATION TABLE FOR DROUGHT-TOLERANT CROPS-EG. COTTON OR SORGHUM
LAIFAC = AFGEN(LAITBL,LAI)
* LEAF AREA INDEX FACTOR, PARTITIONS WATER LOSS BETWEEN PLANT & SOIL
FUNCTION LAITBL =
0.,0.,2.0,0.5,4.0,0.8,6.0,0.9,10.0,0.95,25.,0.95
[36]
** ESTIMATION OF SOIL WATER BALANCE **
WATER = ZHOLD(IMPULS(0.,86400.)*KEEP,RNF)
RAIN = WATER / 86400.
DAYRAI = DLYTOT(DRADI,RAIN)
* CUMULATIVE SUM OF WATER ADDED BY RAINFALL--COMPARE WITH WEATHER DATA
RNF = AFGEN(RNFALL,JULIAN) * 0.01
* RAINFALL (M) OCCURRING ON THIS DATE, IN UNITS OF CM/DAY
PET =AMAX1(PEVV * 0.01 / 86400., RADIAT * PEVVV /...
(AMAX1(0.01,DTR * 1.0 )))
POTENTIAL EVAPOTRANSPIRATION, BASED ON TEMPERATURE (& RADIATION)
(NOT LESS THAN 1% OF AVERAGE TRANSP. DEMAND--NEGATIVES ELIMINATED)
CUMPET = DLYTOT(DRADI,PET)
CUMULATIVE POTENTIAL EVAPOTRANSPIRATION -- COMPARE OUTPUT WITH AVPET
PEVV = AFGEN(PEV,JULIAN) * 0.01
MEASURED POTENTIAL EVAPOTRANSPIRATION IN FIELD (METER PER DAY)
PEVVV = ZHOLD(IMPULS(0.,86400.)*KEEP,PEVV)
SLEVAP = PET * (1.0 - LAIFAC) * 1.0
* SOIL EVAPORATION (METER/SEC), PET REDUCED BY LEAF SHADING
* SOIL WATER MOVEMENT CALCULATIONS **
VOLW = INTGRL (IVOLW , NFLW ,12)
VOLUME OF WATER STORED IN EACH SOIL LAYER
** COMPUTE SOIL WATER CONTENT, POTENTIALS, AND CONDUCTIVITY
NOSORT
*PROCEDURE THETA, POTM, POTH, MPOT, RK, COND, C, D, E, F, C, H ...
* = PROC1(TIME, PB)
* IRRIGATION SYSTEM
PARAM IRFAC = 10.
IRMIN = 10.2118 * IRFAC / 100.
PULSIR = IMPULS(0.O,1800.)
PARAM IRQUAN = (0.0,250.0)
*PARAM IRQUAN = 250.0
PULSSW = INSW((IRMIN+POTM(3)),(IRQUAN*1.0E-6),0.)
VOLW(1) = VOLW(1) + RAIN * DELT + PULSSW * PULSIR
* VOLW(NJJ) = TCOM(NJJ) * 0.30
DO 100 I = 1,NJJ
BULKDS(I) = AFGEN(BULKF,DEPTH(I))
POROS(I) = 1 - (BULKDS(I) / PARTDS)
* POROSITY OF EACH SOIL LAYER
THETA(I) = VOLW(I)/TCOM(I)
DRAING = (AMAX1(0.0,THETA(NJJ)-STHETA))*TCOM(NJJ)/DELT
THETA(I) = AMIN1(THETA(I),STHETA)
VOLW(I) = THETA(I) * TCOM(I)
POTM(I) = -AFGEN(SUTB,THETA(I))
POTH(I) = POTM(I) - DEPTH(I)
100 CONTINUE
* WRITE (6, 854)(POTM(J),J=1,NJ)
[37]
** COMPUTE SOIL HYDRAULIC CONDUCTIVITY **
DO 85 I = 1, NJJ
MPOT = -POTM(I) * 100.0
IF (MPOT.LE. 0.0) GO TO 84
PARAM PB = 21.8258
* BUBBLING PRESSURE (AIR ENTRY VALUE FOR TOPSOIL)
AH = ALPHA * MPOT
RK(I)=(1-(AH)**(NU-1)*(1+(AH)**NU)**(-MU))**2/
((1+(AH)**NU)**(MU/2))
* RELATIVE CONDUCTIVITY (AS A FRACTION OF SATURATED CONDUCTIVITY)
GO TO 87
84 RK(I) = 1.0
* RELATIVE CONDUCTIVITY CAN NEVER BE 
MORE THAN 1.0;
* THUS, SATURATED CONDUCTIVITY APPLIES IF MATRIC POTENTIAL IS POSITIVE
87 CONTINUE
* WRITE(6,854) I, MPOT, RK(I), AH, JDAY
854 FORMAT(12G10.3)
RK(I) = AMIN1(1.00, RK(I))
* CONDUCTIVITY IS LIMITED TO A MAXIMUM OF THE SATURATED CONDUCTIVITY
COND(I) = RK(I) * SATCON
* COND(I) = RK(I) * SATCON / 8.6400E06
* SOIL HYDRAULIC CONDUCTIVITY, METERS/SECOND
85 CONTINUE
* WRITE (6, 854)(RK(J), J=1,NJ)
* WRITE (6, 854)(COND(J),J=1,NJ)
*ENDPRO
* ** COMPUTE VERTICAL SOIL WATER 
FLOW (DARCIAN) **
*PROCEDURE AVCOND, FLW, NFLW , CC, DD, EE = PROC2(POTH,FF)
DO 110 I = 2,NJJ
AVCOND(I) = 5* (COND(I-1) + COND(I))
FLW(I) = AVCOND(I) * (POTH(I-1)-POTH(I)) / DIST(I)
110 CONTINUE
FLW(NJJ+1) = DRAING
NFLW(NJJ+1) = DRAING
PARAM THTAIR = 0.050
POTMAR = - AFGEN(SUTB,THTAIR)
IF (POTM(1) .GT. POTMAR) FLW(1)=-SLEVAP
IF (POTM(1) .LE. POTMAR) FLW(1)=FLW(2)
* WATER FLOW OUT THE TOP IS LIMITED BY SUPPLY IF TOP LAYER IS DRY
DO 120 I = 1,NJJ
NFLW(I) = FLW(I) - FLW(I+1) - RTEX(I)
120 CONTINUE
* ENDPRO
* ** PARTITIONING AGGREGATE ROOT GROWTH BETWEEN SOIL 
LAYERS **
*PROCEDURE BIRTH, EXTENS ,RTGRO, SUMRG,RTDTH, SUMRD,NETGRO, ...
* W, AAA,BBB,CCC,DDD,EEE,FFF,GCG,SUMRTG,SUMRTD = PROC3(POTM,HHH)
[381
ROOT GROWTH IN EACH LAYER
*PARAM BRMIN = -1.00
*PARAM EXTMIN = 
-2.00
PARAM BRMIN = -1.00
PARAM EXTMIN = -2.00
* THRESHOLD POTENTIAL, THE DRIEST SOIL IN WHICH ROOT GROWTH CAN OCCUR
W = AMAX1(0.0, (POTM(2) - EXTMIN))
DO 1010 I=1,NNJ
X = AMAX1(0.0, (POTM(I) - BRMIN))
XX = AMAX1(0.0, (POTM(I) - EXTMIN))
PARAM DEPTHG = 10.
BIRTH(I)=(BR*(1.0-EXP(-AA*X**BB)))/(((DEPTH(I)*DEPTH))**1.)
PARAM BR = 1,OE-04
*PARAM BR = 1,OE-08
* BRANCHING RATE, FOR NEW ROOT GROWTH IN THE SAME SOIL LAYER
EXTENS(I)=(EXTNRT*(1.0-EXP(-AA*XX**BB)))/(((DEPTH(I)*DEPTHG))**1.)
IF ( PRTL(I) .LT. MINRTL * TCOM(I)) EXTENS(I) = 0.
PARAM MINRTL = 5.
PARAM EXTNRT = 3.OE-03
* EXTENSION RATE, FOR NEW ROOT GROWTH FROM ONE LAYER INTO THE NEXT,
* IN UNITS OF METERS/SECOND
PARAM AA = 8.OE-3
PARAM BB = 2.0
* COEFFICIENTS FOR SIGMOID ROOT GENERATION CURVES
1010 CONTINUE
RTGRO(1) = PRTL(1) * BIRTH(1) * (1.0 - FRAC) * TMPFCR
SUMRG = RTGRO(1)
* SUMMATION OF INSTANTANEOUS ROOT GROWTH RATES, OVER ALL SOIL LAYERS
* (EXPRESSED AS METERS ROOTS/SQUARE METER SURFACE/SECOND)
DO 647 I = 2,NNJ
RTGRO(I) = (PRTL(I-1)*EXTENS(I-1) + PRTL(I)*BIRTH(I)) *
(1.0 - FRAC) * TMPFCR
* RTGRO(I) = (PRTL(I-1)*EXTENS(I) + PRTL(I)*BIRTH(I))
* GROWTH EXPRESSED AS METERS/SEC IN 
EACH SQUARE METER OF EACH LAYER
* RTGRO(NNJ) = 0.0
SUMRG = RTGRO(I) + SUMRG
647 CONTINUE
RTGRO(NJ) = 0.0
* TOTAL INCREASE, WHOLE PLANT, IN METERS/SQ. METER/SECOND
SUMRTG = 0.0
DO 648 I = 1,NNJ
IF (SUMRG.EQ.0.00) GO TO 648
RTGRO(I) = RTGRO(I) * TOTRG/SUMRG * LNGFAC
* (BRINGS ACTUAL ROOT GROWTH IN EACH LAYER INTO LINE WITH TOTAL
* PHOTOSYNTHATE AVAILABLE AT ANY GIVEN TIME).
SUMRTG = SUMRTG + RTGRO(I)
648 CONTINUE
IF (YY .GT. 0.0) GO TO 751
IF (TIME.GT.300) GO TO 127
[39]
751 CONTINUE
WRITE(6, 852)
852 FORMAT( /, 15X, 'ROOT LENGTH, M/SQ.M, BY LAYER', T102, 'TIME')
WRITE (6,854) (PRTL(J),J=1,NJ), TIME
* WRITE(6, 851)
851 FORMAT(//, 35X, ' ROOT GROWTH RATE', 50 X, 'MATRIC POTENTIAL')
* WRITE (6,854) (RTGRO(J),J=1,NJ), (POTM(J), J=1,2)
127 CONTINUE
ROOT DEATH IN EACH LAYER
SUMRD = 0.0
DO 649 I = 1, NNJ
RTDTH(I) =PRTL(I) * DTHFAC * TMPFCR
SROOT DEATH, AS METERS/SECOND LOST FROM
SUMRD = SUMRD + RTDTH(I)
649 CONTINUE
RTDTH(NJ) = 0.
EACH LAYER
SUMRTD = 0.0
DO 651 I = 1i, NNJ
IF (SUMRD.EQ.0.) GO TO 651
RTDTH(I) = RTDTH(I) * ROOTDY/SUMRD * LNGFAC
SCALES ACTUAL DEATH RATE TO TOTAL AGGREGATE REQUIRED FOR C-BALANCE
SUMRTD = SUMRTD + RTDTH(I)
TOTAL FOR PLANT, AS METERS/SQ. METER/SECOND
651 CONTINUE
IF (YY .GT. 0.1) GO TO 752
IF (TIME.GT.300) GO TO 652
752 CONTINUE
WRITE (6,859)
859 FORMAT(/, 35X, 'ROOT DEATH RATE')
WRITE (6,854) (RTDTH(J),J=1,NJ)
652 CONTINUE
** SUMMARY OF GROWTH AND DEATH IN EACH LAYER
DO 653 I = 1,NNJ
NETGRO(I) = RTGRO(I) - RTDTH(I)
IF ( ROOTVL(I) .GT. POROS(I) * TCOM(I)) NETGRO(I) = 0
NETWTG(I) = NETGRO(I) / LNGFAC
NETVLG(I) = NETWTG(I) * 100 / ( RTDWPC * 1000.)
653 CONTINUE
NETGRO(NJ) = 0.
NETWTG(NJ) = 0.
NETVLG(NJ) = 0.
SNET CHANGE IN ROOT LENGTH, AS METERS/SECOND CHANGE IN EACH LAYER.
IF (YY .GT. 1.0) GO TO 753
IF (TIME.GT.300) GO TO 654
753 CONTINUE
WRITE (6,856)
856 FORMAT( 35X, 'NET GROWTH')
WRITE (6,854) (NETGRO(J),J=1,NJ)
[40]
I\* I
* WRITE(6,857)
857 FORMAT(/, 50X, 'ITERATION TO FIND POTCR', /)
654 CONTINUE
PRTL = INTGRL(IPRTL,NETGRO,10)
ROOTWT = INTGRL(IRTWT,NETWTG,10)
ROOTVL = INTGRL(IRTVL,NETVLG,10)
PARTIAL ROOT LENGTH, IN EACH SOIL LAYER -- SUM OF GROWTH LESS DEATH
*ENDPRO
J-
* ** ROOT SYSTEM RESISTANCE 
AND WATER UPTAKE **
NOSORT
**PROCEDURE RSSL, PTOTL, RSRT, AAAA, BBBB, CCCC = PROC4(COND,SUMRGoDDDD)
DO 102 I = 1,NNJ
RSSL(I) = 1./(B*COND(I)*(PRTL(I)+NOT(PRTL(I))*I.0E-10))
*PARAM B 
= 
(1.0E-04,1.0E-03,1.0E-02,1.0E-01,1.0)
PARAM B = 1.0E-02
*PARAM B = 1.0E-04
* CONSTANT, RELATING ROOT CONDUCTIVITY TO ROOT LENGTH, AFTER GARDNER.
PTOTL(I) = POTH(I)
* NOTE THAT
PARAM URRS =
* UNITS FOR
PARAM UARS =
* UNITS FOR
RRS(I)
PTOTL IS THE SAME AS HYDRAULIC POTENTIAL IN THIS VERSION
1.00E11
RADIAL RESISTANCE
1.00E11
AXIAL RESISTANCE (IN THE XYLEM)
= URRS / (PRTL(I) + NOT(PRTL(I))*1.0E-10)
~M R= ( _nF-ntl~lE-nl, E-1) _1~E ?
* RADIAL RESISTANCE TO WATER FLOW IN THE ROOT
ARS(I) = UARS * DEPTH(I) / (PRTL(I) + NOT(PRTL(I))*1.0E-10)
* AXIAL RESISTANCE -- ALONG THE XYLEM TRANSPORT SYSTEM
RSRT(I) = RRS(I) + ARS(I)
* COMBINED AXIAL AND CONDUCTIVE RESISTANCE OF ROOTS IN THIS 
LAYER
102 CONTINUE
**ENDPRO
* ** CALCULATION OF POTCR AND PARTITIONING OF ROOT WATER UPTAKE
CUMREM = INTGRL(O.0,SUMR)
* CUMULATIVE WATER REMOVAL (BY ROOT SYSTEM) FROM ALL SOIL LAYERS
**PROCEDURE SUMR,DIFF,DIF,RTEX,POTCR,POTRT,AAAAA,BBBBB = ...
* PROC5(POTH, TRANSP, RUN, RSRT, CCCCC, DDDDD)
COUNT = 0.0
* FLPFLP = -FLPFLP
115 CONTINUE
COUNT = COUNT + 1.0
IF ( COUNT .LT. 100.0 ) GO TO 116
* WRITE (6,666) TRANSP, SUMR, DIF, POTCR, COUNT, TIME
666 FORMAT ( ' T S D P C ' 7E15.5 )
GO TO 165
* IN CASE THE LOOP DOES NOT CONVERGE IN 100 TRIES, 
GO AHEAD ANYWAY
116 CONTINUE
[41]
SUMR = 0.0
DO 150 J = 1,NNJ
I = J
IF ( FLPFLP .EQ. 1.0 ) I = NJ - J + 1
RTEX(I) = AMAX1(0.0 ,(POTH(I) - POTCR) / (RSSL(I) + RSRT(I) ) )
* ROOT EXTRACTION, M/SECOND
IF (RUNS.GT.02) GO TO 117
IF (COUNT.GT.5) GO TO 117
* WRITE(6,854) J, I, POTH(I), POTCR, RSSL(I), RSRT(I), RTEX(I),
* SUMR, TRANSP, DIFF, DIF, COUNT
117 CONTINUE
SUMR = SUMR + RTEX(I)
* SUM OF WATER REMOVALS BY ROOTS IN ALL LAYERS
150 CONTINUE
RTEX(NJ) =0.
RTEX(NJJ) =0.
DIFF = TRANSP - SUMR
* IF (SUMR .LT. TRANSP) RTEX(NJ) = AMAX1(RTEX(NJ),DIFF)
* FOR EACH LAYER, WATER EXTRACTION IS ASSUMED ON THE BASIS OF CURRENT
* VALUE FOR CANOPY POTENTIAL. ITERATION WILL CONTINUE UNTIL EQUAL.
DIF = (SUMR - TRANSP) / TRANSP
IF (COUNT.GT.100.0) GO TO 165
IF(RUNS.CGT.2) GO TO 118
* WRITE(6,754)
754 FORMAT(4X, 'DIF', 7X, 'SUMR', 5X, 'DIFF', 4X, 'POTCR')
* INSERTS HEADERS BETWEEN SUCCESSIVE PASSES IN ITERATION LOOP
* WRITE(6,854) DIF, SUMR, DIFF, POTCR
* WRITE(6, 860)
* WRITE(6,858)
858 FORMAT(9X,'J',9X,'I',3X,'POTH',5X,'POTCR',7X,'RSSL',6X,'RSRT')
860 FORMAT(T65,'RTEX',6X,'SUMR',5X,'TRANSP',6X,'DIFF',6X,'DIF')
118 CONTINUE
IF ( ABS(DIF) .LE. ERROR ) GO TO 165
* ADJUSTMENT OF CANOPY WATER POTENTIAL UP OR DOWN 
AS NEEDED TO BALANCE.
160 POTCR = AMIN1((POTCR - DIF*POTCR*CF),MAXPOT)
PARAM MAXPOT = -2.0
* MAXIMUM ALLOWABLE CANOPY POTENTIAL, (-2 METERS, OR -0.2 BARS)
GO TO 115
165 CONTINUE
DO 170 I = 1,NNJ
POTRT(I) = POTCR + RTEX(I) * RSRT(I)
170 CONTINUE
**ENDPRO
** SUMMARY OF WATER MOVEMENT AND EVAPORATIVE LOSSES
CRTEX = INTGRL ( 0.0 , RTEX ,11)
* CUMULATIVE ROOT EXTRACTION
EVAP = AMIN1(-FLW(1), SLEVAP)
[42]
* EVAPORATION FROM SOIL SURFACE - LIMITED BY AVAILABILITY OF WATER
* (COMING FROM DEEPER SOIL LAYERS) OR BY THERMAL INSOLATION AT SURFACE
CEVAP = INTGRL(O.0, EVAP)
CUMULATIVE EVAPORATION FROM SOIL SURFACE
DRAIN = INTGRL (O.,DRAING)
INTERNAL DRAINAGE, AS WATER PASSES THE BOTTOM OF THE LOWEST 
LAYER
FLWNJN = - AMIN1(0.O,FLW(NJJ))
CAPRIS = INTGRL (0.,FLWNJN)
* CAPILLARY RISE, PAST THE BOTTOM LAYER
CTRAN = INTGRL (O.,TRANSP)
* CUMULATIVE TRANSPIRATION, AS M/SQUARE 
METER
IF (KEEP.NE.1) GO TO 314
WRITE(11,313) HOURS,RADIAT,TEMP,SHOOTW,ROOTW,PHOTSN,WATRST
313 FORMAT(5F8.3,G10.2,F8.3)
314 CONTINUE
RUNS = RUNS + 1
** * * * * * * * * * * TERMINAL SEGMENT
TERMINAL
PRINT DAY,HOUR, PHOTSN, POTCR, SOLCHO, SHOOTW, ROOTW,...
ROOTW, CTRAN, CEVAP, DELT
ZYY = DEBUG(01,TIME)
OUTPUT DAY,RADIAT,RAIN
LABEL RADIATION AND RAINFALL
LABEL
PAGE XYPLOT, MERGE,HEIGHT=3.,WIDTH=05.0
OUTPUT DAY,TEMP,STEMP
LABEL AIR AND SOIL TEMPERATURE
LABEL
PAGE XYPLOT, MERGE,HEIGHT=3.,WIDTH=05.0,GROUP=2
OUTPUT DAY,SHOOTW,ROOTW,DRYWT
LABEL DRY WEIGHT OF SHOOT AND ROOT (KG/M2)
LABEL
LABEL
PAGE XYPLOT, MERGE,HEIGHT=3.,WIDTH=04.0,GROUP
OUTPUT DAY,LAI,ROOTL
LABEL LEAF AREA INDEX AND ROOT GROWTH
LABEL
LABEL
PAGE XYPLOT, MERGE,HEIGHT=3.,WIDTH=04.0
OUTPUT DAY,FRAC(0.0,1.0)
LABEL BIOMASS PARTITIONING
LABEL
LABEL
PAGE XYPLOT, MERGE,HEIGHT=3.,WIDTH=04.0
OUTPUT DAY,PHOTSN
LABEL PHOTOSYNTHESIS (KG/M2/SEC)
LABEL
PAGE XYPLOT, MERGE,HEIGHT= 3.,WIDTH=04.0
[43]
OUTPUT DAY,POTCR
LABEL CANOPY WATER POTENTIAL
LABEL
PAGE XYPLOT, MERGE,HEIGHT= 3.,WIDTH=04.0
OUTPUT DAY,TOPGRO, TOTRG, SHOOTD, ROOTDY
LABEL TISSUE GROWTH AND DEATH (KG/M2/S)
LABEL
PAGE XYPLOT, MERGE,HEIGHT=3.,WIDTH=05.0,GROUP=4
OUTPUT DAY,SHMRES, SHGRES, RTMRES, RTGRES
LABEL COMPONENTS OF RESPIRATION ( KG/M2 )
LABEL
LABEL MAINTENANCE AND GROWTH OF SHOOT AND ROOT
LABEL
PAGE XYPLOT, MERGE,HEIGHT=3.,WIDTH=04.0,GROUP=4
OUTPUT DAY,NETGRO(1-8)
LABEL NET INCREASE IN ROOT LENGTH (M/M2/S)
LABEL
PAGE XYPLOT, MERGE,HEIGHT=3.,WIDTH=04.0,GROUP
OUTPUT DAY,TRANSP,EVAP
LABEL TRANSPIRATION AND EVAPORATION (M/S)
LABEL
PAGE XYPLOT, MERGE,HEIGHT=3.,WIDTH=04.0,GROUP
OUTPUT DAY,CTRAN,CEVAP
LABEL CUMULATIVE WATER UPTAKE AND EVAPOTRANSPIRATION (M)
LABEL
PAGE XYPLOT, MERGE,HEIGHT=3.,WIDTH=04.0,GROUP
OUTPUT DAY,NFLW(1-8)
LABEL NET FLOW OF WATER (M3/M2/S)
LABEL
PAGE XYPLOT, MERGE,HEIGHT=3.,WIDTH=04.,GROUP
OUTPUT DAY,RTEX(1-8)
LABEL ROOT EXTRACTION (M3/M3/SEC)
LABEL
PAGE XYPLOT, MERGE,HEIGHT=3.,WIDTH=04.,GROUP
OUTPUT DAY,POTM(1-8)
LABEL SOIL MATRIC POTENTIAL
LABEL
PAGE XYPLOT,MERGE,HEIGHT=3.,WIDTH=04,GROUP
OUTPUT DAY,THETA(1-8)
LABEL SOIL WATER CONTENT
LABEL
PAGE XYPLOT,MERGE,HEIGHT=3.,WIDTH=04,GROUP
OUTPUT DAY,PRTL(1-8)
LABEL PARTIAL ROOT LENGTH (M/M2)
LABEL
PAGE XYPLOT,MERGE,HEIGHT=103.,WIDTH=04.,GROUP
END
STOP
ENDJOB
[44]
APPENDIX B:
FORTRAN LISTING OF SIMULATION MODEL
C
C
C WATER UPTAKE AND ROOT GROWTH IN A HOMOGENEOUS SOIL PROFILE
C
G SUBROUTINE UPDATE (SUPPLIED BY CSMP TRANSLATOR)
C (AS MODIFIED BY M, G. HUCK & G. HOOGENBOOM)
C VERSION 4.0-- MAY 1985
G
C** SYSTEM SEGMENT
G
G SYSTEM SEGMENT OF MODEL
INTEGER RUNS, MONTH, JDAY, DATE
REAL*%4 IMPULSNOTTIRFAGIRMINIRQUANPULSIRPULSSWPULS1,INSW
REAL$% VOLW (20)
REAL*%8 PRTL ( 20),IPRTL(20),IRTWT(20),IRTVL(20),ROOTWT(20)
REAL*-8 CRTEX( 20),ROOTVL(20)
REAL*4 NFLW ( 20),IVOLW( 20), POROS(20),BULKDS(20)
REL*% NTGO( 20),NETWTG(20),NETVLG(20)
REAL*F'4 RTEX ( 20)
REAL*4 TIME, ZZTIME, PRDEL,LSNHSMINRTL,NU,MU
EQUIVALENCE(ZZTIMETIME )
C EQUIVALENCE(DFOVTXDFGLTX, SUNTBX)
REAL*o8 SOLCHO, CUMRAD, DAYCUM, DRCI, DROI, DRADI,
$ CSTMRS, CRTMRS, SHOOTW, POTCRD, ROOTW, CUMRAN, CUMPET,
$ CUMREM, CEVAP, DRAIN, CAPRIS, CTRAN ,SNLS
REAL*-4 RSRT ( 20)
REAL*-4 DIST ( 20)
REAL*,,4 THETA( 20)
REAL*'4 RRS ( 20)
REAL*4 ARS ( 20)
REAL*o4 FLW ( 20)
REAL*-4 COND ( 20)
REAL*-4 AVGOND( 20)
REAL*4 POTRT( 20)
REAL*f'4 P0TH ( 20)
REAL*-4 POTM ( 20)
REAL*-4 RSSL ( 20)
REAL*4 Y ( 20)
REAL*4 SCALE( 20)
REAL*,,-4 BIRTH( 20)
REAL*F'4 EXTENS( 20)
RE A '-A*4 TRO ( 2)
[45]
REAL*4 MINTMP
REAL*4 MAXSTM
REAL*4 MINSTM
REAL*8 INTGRL, OLDVAL
REAL*4 ICHO ,JULIAN, LFOV, LFCL, 
LOPOT, LAT
1,ISHOOT,IROOT ,IPER ,LEAFTH,LNGFAC,MAXFOT,MAXPOT,MAXRAD,LAITBL
1,IL ,IRTL ,LAI ,LAIFAC,MPANEV,MPOT, MXPHOT,LEAFW
C
REAL*4 SMAX(6),SMIN(6),SUNTBX(10),DFCLTX(10),DFOVTX(10),
1DFOVTY(10),DFCLTY(10),SUNTBY(10),SUTBX13),SUTB 
Y(13),
2FRACTX(5),FRACTY(5),DTBLX(6),DTBLY(6),TRANX(6),TRANY(6),
3AVPETX(2),AVPETY(2),LAITX(6),LAITY(6),TIMEX(400),RADNY(400),
4MAXTMY(400),MINTMY(400),RAINY(400),PEVAPY(400),MAXSTY(400),
5MINSTY(400),BULKX(5),BULKY(5)
DIMENSION PTOTL(20)
DIMENSION RK(20), DEPTH(20)
C
C TABLE DEFINITIONS:
DATA SUNTBX/ 0., 5., 15., 25., 
35., 45., 55., 65.,
$ 75., 90./
DATA DFCLTX / 0., 5., 15., 25., 35., 
45., 55., 65.,
$ 75., 90./
DATA DFOVTX / 0., 5., 15., 25., 35., 
45., 55., 65.,
$ 75., 90./
DATA DFOVTY / 0., 6., 26., 45., 64., 
80., 94., 105.,
$ 112., 116./
DATA DFCLTY / 0., 29., 42., 49., 
56., 64., 68., 71.,
$ 75., 77./
DATA SUNTBY / 0., 0., 88., 175., 262., 336., 
402., 452.,
$ 483., 504./
C
C FUNCTION DEFINITIONS:
C FUNCTION SUTB = (.025, 20.) , (.05 , 5.) , (.075 
, 3.0),
C (.10 , 1.7) , (.15 , 0.6) , (.20 , .25 ) ,
C (.25 , .15) , (.30 , .10)
C (.35 , .05) , (.40 , 0.01) , (.45, 0.0)
C (.50, -1.00)
DATA SUTBX/0.00,.0674,.0940,.1119,.1263,.1363,0.1531,.1705,.2063,
$ 0.2461,0.36,0.42,0.50/
DATA SUTBY/60.,40.8,21.21,15.27,7.325,4.11,2.01,0.99,0.425,
$ 0.264,0.0,0.0,0.0/
C FUNCTION FRACTB = -500.,.05, -200.,.25, -050.,.70, -10.,.95,
C 100.,.95
DATA FRACTX/-500., -200., -50., -05., +100. 1
DATA FRACTY/ .05, .20, .65, .90, .90 I
C FUNCTION DTBL = 0.0,0.0, 2.0,0.03, 5.0,0.33, 
07.0,0.97, 10.,100.
DATA DTBLX/0.0, 2.0, 5.0, 7.0, 
10.0 , 25.!
DATA DTBLY/0.0, .03, 0.33, 0.97, 
1.0 , 1.0/
C FUNCTION TRNTBL = -500.,.05, -200.,.05, -100.,0.95, 
0.,1.0, 100.,1.0
DATA TRANX/-500., -245., -163., -112., 0.001, +100. I
DATA TRANY! 0.05, 0.05, 0.50, 0.95, 1.00, 1.00 /
C FUNCTION LAITBL = 0.,0., 3.0,0.5, 6.0,0.9, 
10.0,0.95
DATA LAITX/ 0.0, 2.0, 4.0, 6.0, 10.0, 25.0 I
DATA LAITY! 0.0, 0.5, 0.8, 0.9, 0.95, 0.95 I
[46]
DATA BULKX/0.0,0.5, 1.0,1.5 ,2.O/
DATA BULKY/1.52.,52,1.52,1.52,1.52/
DATA RADNY/400*,,1 .0/
DATA MAXTMY/400*,,40. I, MINTMY/400*-'10,./
DATA RAINY/400*0,-. I, PEVAPY/400*.f I.
DATA MAXSTY/400*,30./, MINSTY/400*"1O./
C
C If*f - % % J 1 f INITIAL SEGMENT 0% I% f% f% f% f% % I% 0% % 0% f
C INITIAL SEGMENT OF MODEL
C
RUNS=0
KEEP = 1
TIME = 0.ODOO
HOURS=TIME/3600 .0
DAY=HOURS/24 .00
P1=3.14159
RAD=PI /180.
READ (8,*1) FINTIM, OUTDEL, PRDEL, DELT, BGNDAY
READ (8,*f') IPER, ISHOOT, IROOT, LNGFAC, NJ,RTDWPC
NJJ = NJ + 1
NNJ = NJ 
-1
READ (8,*o) (ITHETA(I), 11I,NJJ)
READ (8,*-) (RRL(I),I=1,NJ)
READ (8,*,,) (TcoM(I),I=1,NJJ)
READ (8,-,*) LOPOT, HIPOT
C FOR LINEAR INTERPOLATION OF POTCR, WHEN THIS IS USED.
READ (8,-*%) DTRDEM, SATCON, ZLAM, PARTDS,THTAIR,STHETA,ALPHA,NU
READ (8,*) REFT, REFTS, RSPFAC, MXPHOT, DKPHOT, EFF
READ (8,-*) CONVRT, DELAY, FRG, AGFAC, LEAFTH, STWTR
READ (81,'*) GROFAC, DTHFAC, PB, BRMIN, EXTMIN, MINRTL
READ (8,*%) BR, EXTNRT, AA, BB, B, DEPTHG
READ (89,*%) URRS, UARS, MAXPOT, OUTF
READ (81%*) POTCR, LSNHS, DRCI, DROI, DRADI
READ (8,*') CF, ERROR, LAT
C
DO 79 I1=1,400
TIMEX(I) =I
79 CONTINUE
C
C
CSLT=COS (RAD*'LAT)
SNLT=SIN( RAD*'LAT)
PHTCAR=30. /44.
C MOLECULAR WEIGHT/VOLUME RATIO FOR C02
C~
[47]
WRITE(6,92)SIMDAY,RADN,MAXTEM,MINTEMCMRAINPEVAPMAXSTM,
$ MINSTM
C
WRITE(19,1853)
WRITE(6,1853)
1853 FORMAT(/,' INITIATE ',/,'SIMDAY',3X,'RADN',3X,' MAXTEM',
$ ' MINTEM', ' CMRAIN', 
' PANVAP','MAXSTM',
$ ' MINSTM', ' MONTH', ' DATE', 
/ )
IF(SIMDAY.GT.400)GO TO 193
C
C
DO 01 KOUNT=1,365
C READ(12,91,END=193)SIMDAY, RADN,MAXTEMMINTEMCMRAINPEVAP,
C $ MAXSTM, MINSTM, MONTH, DATE
READ(12,91,END=193,ERR=193) RADN,MAXTEMMINTEMCMRAINPEVAP,
$ MAXSTM,MINSTM,SIMDAY
JDAY = SIMDAY
CALL MTIME(MONTHDATEJDAY)
C MAXSTM = MINSTM + 0.75 * (MAXTEM - MINTEM)
C (NOTE THAT THIS APPROXIMATION IS NEEDED ONLY FOR SOUTHERN HEMISPHERE)
IF(SIMDAY.GT.400)GO TO 101
92 FORMAT(F6.1,E1O.2,6F07.2,215)
101 CONTINUE
K = SIMDAY
TIMEX(K) = SIMDAY
RADNY(K) = RADN * 3600.
C CONVERTS FROM LY/SQ CM. INTO JOULES/SQ. METER
MAXTMY(K) = ( MAXTEM - 32. ) * 50/9.
MINTMY(K) = ( MINTEM - 32. ) * 5.19.
C CONVERTS FROM DECREES FAHRENHEIT INTO DECREES C.
RAINY(K) = CMRAIN * 2.54
PEVAPY(K) = PEVAP * 2.54
C CONVERTS INCHES OF RAINFALL OR EVAPORATION INTO CENTIMETERS.
MAXSTY(K) = ( MAXSTM - 32. ) * 5.19.
MINSTY(K) = ( MINSTM - 32. * 5/9,
WRITE(6,92)SIMDAY,RADNY(K),MAXTMY(K),MINTMY(K),RAINY(K),PEVAPY(K),
$ MAXSTY(K),MINSTY(K),MONTH,DATE
WRITE(19,92)SIMDAY,RADNY(K),MAXTMY(K),MINTMY(K),RAINY(K),PEVAPY(K)
$ , MAXSTY(K),MINSTY(K),MONTH,DATE
01 CONTINUE
C
193 CONTINUE
KK = START
LL = SIMDAY
C4
[48]
DRYWT = SHOOTW + ROOTW
STEMW = STWTR* SHOOTW
LEAFW = SHOOTW- STEMW
ICHO=( ISHOOT+IROOT)*f'IPER/ (1 -IPER)
SOLCHO = ICHO
I RTL=ROOTW*'LNGFAC
LAI =LEAFW*V'LEAFTH
ETA=2 .0+3 . 0*fZ LAM
C
DEPTH( 1)=. 5*f(TCOM( 1))
DIST(1)=DEPTH( 1)
IVOLW( 1)=ITHETA(1)*-TcoM( 1)
C
DO 20 I=2,NJJ
DIST(I )=.5s*(TcOM(I-1)+TCOM(I))
DEPTH( I)=DEPTH( I-i )+DIsT( I)
IVOLW( I)=ITHETA( I )*,TCoM( I)
VOLW(I =ITHETA(I *TCOM(I)
THETA(I =voLw(I/TcoM(I
BULKDS(I) =AFGEN(BULKX,BULKYDEPTH(I))
POROS(IM 1 - (BULKDS(I)I PARTDS)
20 CONTINUE
POROS(1)= POROS(2)
C
DO 30 I=1,NJ
DRAING =(AMAX1(0.0,THETA(NJJ)-STHETA))*-TCOM(NJJ)/DELT
THETA(I) = AMIN1(ITHETA(I),STHETS)
POTM( I)=-AFGEN( SUTBX, SUTBY ,THETA( I))
C POTM(I) = -0.01 * EXP(-37.31 If' THETA(I + 16.97)
C (CHOOSE LOOKUP TABLE OR FUNCTION, DEPENDING ON DATA AVAILABLE)
POTH( I)=POTM( I)-DEPTH( I)
IPRTL( I)=IRTL*#'RRL( I)
IRTWT(I = IPRTL(I)/LNGFAC
IRTVL(I = IRTWT(I)*,,100./(RTDWPC*F'1000)
RRS(I)=URRS/ (IPRTL(I) + NOTT(IPRTL(I))*1,-.0E-10)
ARS(I)=UARS*,-DEPTH(I)I (IPRTL(I) + NOTT(IPRTL(I))*1'%.OE-10)
RSRT(I )=RRS(I )+ARS(I)
30 CONTINUE
DO 15 I=13,NJJ
RTEX(I) = 0.0
NFLW(I = 0.0
15 FLW(I)=0.0
RISE = 4.8
PLSNHS = 0.0
TOPGRO = 0.0
[49]
DROI = DROP
DRADI = 1.OE-1O
DRADZ = DRADI
DROZ = DROI
DRCZ = DRCI
RAINZ = 0.00
DAYRAI=0.00
DRADI = 0.00
PULS = 0.00
PEVV = 0.00
CSTMRS = 0.0
CRTMRS = 0.0
CUMRAN = 0.00
CUMPET = 0.ODO
DO 37 I-= 1,NJ
VOLW(I) = IVOLW(I)
PRTL(I) = IPRTL(I)
ROOTWT(I) = IRTWT(I)
ROOTVL(I) = IRTVL(I)
CRTEX(I)=0.0
RTEX(I) =0.0
37 NETGRO(I = 0.0
CUMREM = 0.0
CEVAP = 0.ODO
DRAIN = 0.0
CAPRIS = 0.0
CTRAN = 0.0
SUMR = 0.0
COUNT = 0.0
DTOT = 0.0
DTOTI = 0.0
DTOTZ = 0.0
RATE = 0,0
C
TIME
HOUR
xxx
YY
0. ODOO
0.0
0.0000
0.0
WRITE(1,876)
876 FORMAT(1X, 'HOURS', 3X, 'POTH(1', 2X, 'POTH(2) ETC.
WRITE(2,877)
877 FORMAT(2X, 'HOURS', 
4X, 'NFLW(1) NFLW(2) 
ETC. --- >')
WRITE(3,878)
878 FORMAT(2X, 'HOURS', 5X, 'HOUR', 4X, 'POTCRE', 4X, 'POTCR',
$ 6X, fSOLCHO', 5X, 'SHOOTW', 4X, 'ROOTW', 5X, 'CTRAN', 5X,
$ 'CEVAP', 4X, 'JULIAN')
WRITE(4,879)
879 FORMAT(3X, 'HOURS', 3X, 'PHOTSN', 4X, 'GROWTH', 5X, 'RESP
$ 6X, 'Z7A022', 4X,'SUMR', 6X,
$ 'EVAP', 5X, 'TRANSD')
WRITE(9,880)
880 FORMAT(2X, 'HOURS', 5X, 'RADN', 6X, 'TEMP', 7X, 'PET',
$ 7X, 'RSSL(3)', 3X, 'RSRT(3)', 3X, 'COND(3)', 5X, 'RESP',
[50]
5X9
>1)
$ 'SUMRTG', 4X, 'SUMRTD')
WRITE(10,881)
881 FORMAT(2X, 'HOURS RTEX(1) RTEX(2) ETC. --- > ')
WRITE(11,882)
882 FORMAT(2X, 'HOURS', 
6X, 'LFOV', 6X, 'DTR', 
6X, 'DTRR', 6X,
$ 'LFCL', 6X, 'CRO', 7X, 'CRC', 7X, 'RANGE', 6X, 'AVAT', 5X,
$ 'STEMP')
WRITE(13,883)
883 FORMAT(2X, 'HOURS', 6X, 'MONTH', 4X, 'DATE', 6X, 'HOUR', 6X,
$ 'RAIN', 6X, 'ROOTDY', 4X, 'LAI', 7X, 'FLW(8)', 6X,' TEMP',
$ 5X,'STEMP')
WRITE(14,884)
884 FORMAT(2X, 'HOURS', 6X, 'MONTH', 4X, 'DATE', 6X, 'HOUR', 6X,
$ 'DRC ', 6X, 'DRCP ', 4X, 'DRO', 7X, 'DROP ' 6X, 'LFCL',
$ 5X, 'RADCAL')
WRITE(15,885)
885 FORMAT(2X, 'HOURS', 6X, 'MONTH', 
4X, 'DATE', 6X, 'HOUR', 6X,
$ 'WATRST', 4X, 'PHOTC ', 4X, 'PHOTD', 5X, 'PHOTSN', 6X, 'LAI
$ 5X, 'LFCL ')
WRITE(6,1856)
1856 FORMAT(/,' INITIATION NOW COMPLETE. ENTER DYNAMIC LOOP',//)
C
C * * * * * * * * * DYNAMIC SEGMENT 
* * * * * * * * * * * * * * *
C DYNAMIC SEGMENT OF MODEL
C
C
C
6001 CONTINUE
JULIAN=BGNDAY+TIME/86400.
JDAY=JULIAN
CALL MTIME(MONTH,DATE,JDAY)
T=MONTH
TT=T
MTH=MONTH-0.5+((DAY/30))
RUN=RUNS
HOURS=TIME/3600.0
HOUR=AMOD(HOURS,24.0)
DAY=HOURS/24.00
YY = AMOD(HOURS,OUTDEL)
XXX = AMOD(TIME,PRDEL)
IF (TIME.GT.1.0D15) GO TO 6002
C IF (YY .GT.0.01 ) GO TO 6002
6002 CONTINUE
C
C
IF (TIME.GT.FINTIM) GO TO 99
IF (HOURS.GT.1200.) GO TO 99
IF (POTCR.LT.-476.) GO TO 99
IF (SOLCHO.LT.+1.0E-07) GO TO 99
C
C
DEC=-23.4*COS(2.*PI*(JULIAN+10.)/365.)
C CHANGE TO -23.4 WHEN WORKING WITH DATA FROM NORTHERN HEMISPHERE
C DEC=+23.4*COS(2.*PI*(JULIAN+10.)/365.)
[51]
C (+10 IS TIME BETWEEN DEC 21 AND DEC 31--FOR SIDEREAL YEAR)
C
SNDC=SIN(RAD*DEC)
CSDC=COS(RAD*DEC)
SNHSS=SNLT*SNDC+CSLT*CSDC*COS(PI*(HOUR+12.)/12.)
C SINE OF SUN HEIGHT(INCLUDING NEGATIVE VALUES)
SNLS = SNHSS - LSNHS
RISE1= (AND(SNHSS,-LSNHS))-0.5
RISE2= HOUR-SNHSS*DELT/((NOTT(SNLS)+SNLS)*3600.)
RISE = ZHOLD(RISE,RISEI,RISE2)
C TIME OF SUNRISE
LSNHS =SNHSS
C SINE HEIGHT OF SUN ON PREVIOUS DAY
C
DTRR=AFGEN(TIMEX, RADNY,(JULIAN-0.0))
C DAILY TOTAL GLOBAL RADIATION(MEASURED, INTERPOLATED FROM DAY TO DAY.
DTR=RADNY(JDAY)
C DAILY TOTAL RADIATION (FROM INPUT FILE--JOULE/METER2/DAY)
SNHS=AMAX1(0.,SNHSS)
C SINE, HEIGHT OF SUN, NEGATIVE VALUES REMOVED
HSUN=ATAN(SNHS/SQRT(1.-SNHS*SNHS))/RAD
C HEIGHT OF THE SUN, EXPRESSED IN DEGREES, ABOVE HORIZON
SUNDCL=AFGEN(SUNTBX,SUNTBY, HSUN)
C SUNLIGHT, DIRECT, UNDER A CLEAR SKY.
DIFCL=AFGEN(DFCLTX,DFCLTY,HSUN)
C DIFFUSE VISIBLE RADIATION UNDER A STANDARD CLEAR SKY
CRC=(SUNDCL+DIFCL)*2.
C CURRENT RADIATION INTENSITY UNDER A CLEAR SKY (DIRECT + DIFFUSE)
DIFOV=AFGEN(DFOVTX, DFOVTY,HSUN)
C DIFFUSE VISIBLE RADIATION UNDER A STANDARD OVERCAST
DIFON=0.7*DIFOV
C DIFFUSE NEAR-INFRARED UNDER A STANDARD OVERCAST SKY
CRO=DIFOV+DIFON
C CURRENT RADIATION UNDER AN OVERCAST SKY
CALL DLYTOT(DROZ,DRO,DROI,CRO,TIME,DELT)
CALL DLYTOT(DRCZ,DRC,DRCI,CRC,TIME,DELT)
PULS = IMPULS(TIME,0.0,86400.)
DRCP = ZHOLD(DRCP,PULS,DRC)
DROP = ZHOLD(DROP,PULS,DRO)
FCL=(DTR-DROP) /(AMAX1((DRCP-DROP),0.0001))
C FRACTION OF THE TIME THAT SKY IS CLEAR
FOV=1.-FCL
C FRACION OF THE TIME THAT SKY IS OVERCAST
LFOV=AMIN1(1.,FOV)
LFOV=AMAX1(0.,LFOV)
LFCL=1.-LFOV
C FRACTIONS FCL AND FOV RESTRAINED BETWEEN 0 AND 1 (IN CASE OF ERROR)
RADCAL=LFCL*CRC+LFOV*CRO
C RADIATION, CALCULATED--INSTANTANEOUS RATE
CUMRAD =INTGRL (CUMRAD,RADCAL,DELT)
C CUMULATIVE TOTAL RADIATION RECEIVED--COMPARE WITH INPUT VALUES.
CALL DLYTOT(DRADZ,DRAD,DRADI,RADCAL,TIME,DELT)
C
C
[52]
C ** ESTIMATION OF TEMPERATURE EFFECTS **
C
C
C
MAXTEM = AFGEN(TIMEX,MAXTMY,(JULIAN-(14./24.)))
MINTEM = AFGEN(TIMEX,MINTMY,(JULIAN-(RISE/24.)))
C LINEAR INTERPOLATION FROM INPUT DATA-FILE
RANGE = (MAXTEM - MINTEM) * 0.250
C GENERATING FACTOR -- MINIMUM AT 3 AM; MAXIMUM AT 3 PM
AVAT = (MAXTEM + MINTEM) * 0.500
C AVERAGE AIR TEMPERATURE
CALL WAVE(TEMP,JULIAN,HOUR,MINTEM,MAXTEM,RISE,PI)
C COMPUTED AIR TEMPERATURE, DEGREES C.
C
MAXSTM = AFGEN(TIMEX,MAXSTY,(JULIAN-(14.+4.)/24.))
MINSTM = AFGEN(TIMEX,MINSTY,(JULIAN-(RISE+4.)/24.))
C LINEAR INTERPOLATION FROM INPUT DATA-FILE
RANGES = (MAXSTM - MINSTM) * 0.500
C AMPLITUDE (RANGE) OF DAILY SOIL TEMPERATURE OSCILLATIONS
AVST = (MAXSTM + MINSTM) * 0.500
C AVERAGE SOIL TEMPERATURE, FROM DAILY MEASUREMENT DATA
C
CALL WAVE(STEMP,(JULIAN-0.16),(HOUR-4.),MINSTM,MAXSTM,RISE,PI)
C SOIL TEMPERATURE, AS DEGREES CELSIUS
C
C
TMPFCS = 10.0 ** ((TEMP-REFT) * 0.030103)
TMPFCR = 10.0 ** ((STEMP-REFTS) * 0.030103)
C BIOLOGICAL Q-10 -- DOUBLING REACTION RATE AT EACH 10 DEGREE TEMP CHNG
C
C*
C** ** ESTIMATION OF RADIATION INTENSITY **
C*
C*
C* ** PHOTOSYNTHETIC ACTIVITY **
C*
LAI=LEAFW *LEAFTH
LAIFAC=AFGEN(LAITX, LAITY, LAI)
WATRST=AFGEN(TRANX, TRANY, POTCR)
C PHOTOSYNTHETIC ACTIVE RADIATION
SLLA = AMINI(LAI,2*SNHS)
C SUNLIT LEAF AREA
DLLA = LAI - SLLA
C TOTAL LEAF AREA IN THE SHADE
XOVC = RADOPH * EFF / ( MXPHOT * LAI )
POVC = XOVC / ( XOVC + 1. )
PHOTD = LAI * MXPHOT * POVC
C MAXIMUM CANOPY PHOTOSYNTHESIS UNDER AN OVERCAST SKY
XS = ALOG ( 1+(0.45 * EFF*RADCPH/(AMAX1(SLLA,0.0001)*MXPHOT)))
PS = xs / ( 1 + XS )
PHOTS = SLLA * MXPHOT * PS
[53]
C MAXIMUM CANOPY PHOTOSYNTHESIS UNDER A CLEAR SKY FOR SUNLIT LEAFAREA
XSH = ALOC( 1+(0.55 * EFF RADCPH/(AMAXl(DLLA,0.OOO1)*MXPHOT)))
PSH = XSH / ( 1 + XSH )
PHOTSH = DLLA * MXPHOT PSH
C MAXIMUM CANOPY PHOTOSYNTHESIS UNDER A CLEAR SKY FOR SHADED LEAFAREA
C
PHOTC = PHOTS + PHOTSH
IF ( LAI .CT. 3 ) CO TO 31
IF ( RADCAL .LT. 1.0 ) GO TO 31
FINT = ( 1. - EXP(-O.8*LAI))
Cl = PINT * PHOTC
C2 = LAI * MXPHOT
01 = FINT * PHOTD
02 = C2
IF ( Cl .CT. C2 ) CO TO 32
CO = Cl
Cl = C2
C2 = CO
32 CONTINUE
PHOTC = C2 *(1. - EXP( AMAXl(-50, ( -Cl/C2))))
IF( 01 GCT, 02 )GO TO 33
00 -01
01 =02
02 =00
33 CONTINUE
PHOTD = 02*( 1. - EXP( AMAX1(-50.,( -01/02))))
31 CONTINUE
PHOTSN = WATRST PHOTC LFCL + PHOTD LFOV)
PHOTOSYNTHETIC RATE (NET CARBON FIXATION, KG/SQUARE METER/SECOND
* *d RESERVE LEVELS AND TISSUE GROWTH *
SHMRE S=SHOOTW*'TMPFC S*fRS PFAC
CSTMRS =INTGRL (CSTMRS
SHGRES=TOPGRO*F'CONVRT
RESPSH=SHMRES+SHGRES
RTMRE SROOTW*F'RS PFAC*f'TMPFCR
CRTMRS =INTCRL (CRTMRS
RTGRESTOTRG*CONVRT
RESPRT=RTMRE S +RTGRES
RESP=RESPSH+RESPRT
SHMRES ,DELT)
RTMRES ,DELT)
ZZ1022 =(PHOTSN*PHTCAR-GROWTH-RESP)
SOLCHO =INTGRL (SOLCHOZZ1022,DELT)
FRAC=AFGEN( FRACTX, FRACTY, POTCRE)
TOPGRO=TMPFCS*CROFAC*SOLCHO*FRAC
TOTRC=(1,.0-FRAC )*TMPFCR*CROFAC*SOLCHO'
CR0 WTH=TOPCRO+TOTRC
RESL=SOLCHO/ (SoLCHO+RooTW+SHOOTW)
C* RESERVE LEVEL, % FREE CARBOHYDRATE IN TISSUES
IF (RESL.GT.0.75) CO TO 99
SHOOTW =INTGRL(SHOOTW,(ToPGRO-SHOOTD),DELT)
ROOTW =INTGRL(ROOTW, (TOTR-ROOTDY) ,DELT)
ROOTL = ROOTW * LNCFAC
[541
C
C
C*
C*
C*
DRYWT = SHOOTW + ROOTW
STEMW =STWTR *SHOOTW
LEAFW = SHOOTW- STEMW
DTHBCN=AFGEN(DTBLX, DTBLY, LAI)
AGING=ACFAC*'(DAY/30.)
SHOOTD=SHOOTW*-TMPFCS*'DTHBGN*'AGI NG
ROOTDY=ROOTW IRE SL*fDTHFAC*. 'TMPFCR
C
C 0%0 OVERALL WATER BALANCE *
C
RNF=AFGEN(TIMEX, RAINY, JULIAN)"*001
WATER= RAINY( JDAY )*o . 01
RAIN=WATER/86400.
CALL DLYTOT(RAINZ,DAYRAIDRADI ,RAINTIMEDELT)
CUMRAN -INTCRL (CUMRAN ,RAIN ,DELT)
C
PEVV=AFCEN(TIMEX, PEVAPY,JULIAN)lf*0.01
PEVVV=PEVAPY(JDAY)*'0 .01
PET=AMAX1(PEVV*-0.01/86400. ,RADCAL*'PEVVV/(AMAX1(0.01,DTR*10)
CUMPET =INTCRL (CUMPET ,PET ,DELT)
TRANSD = PET* LAIFAC
C TRANSPIRATION DEMAND IN THE ABSENCE OF STOMATAL CLOSURE--USED 
IN
C ESTIMATING POTCR BY THE INTERPOLATION METHOD (BUT NOT 
ITERATIVE)
TRANS P=WATRST*PET*'LAI FAC
SLEVAP=PET*-(1 .0-LAIFAC)*'1 .0
IRFAC = 10.
IRMIN = 10,2118* IRFACI 100.
PULSIR = IMPULS(TIME,0*0,1800.)
IRQUAN = 000.0 *1.OE-6
PULSi = IRMIN+POTM(3)
PULSSW = INSW(PULS1,IRQUAN,0)
VOLW(1)= VOLW(1) + RAIN* DELT + PULSSW *% PULSIR
C
DO 1001 I = 13PNJJ
BULKDS(I) = AFCEN(BULKXBULKYDEPTH(I))
POROS(I = 1 - (BULKDS(I)/ PARTDS)
THETA(I = VOLW(I)ITCOM(I)
DRAING =(AMAX1(0.0,THETA(NJJ)-STHETA))*elTCOM(N.JJ)/DELT
THETA(I =AMIN1(THETA(I),STHETA)
VOLW(I) =THETA(I)% TCOM(I)
POTM( I)=-AFCEN( SUTBX, SUTBY ,THETA( I))
C POTM(I) = -0.01 * EXP(-37.31 * THETA(I + 16.97)
C (CHOOSE LOOKUP TABLE OR FUNCTION, DEPENDING ON DATA AVAILABLE)
POTH(I )=POTM(I )-DEPTH(I)
10011 ON~rTINUET
[551
C RK(I)=(PB/MPOT)-**''ETA
CO TO 87
84 RK(I)=l.0
87 CONTINUE
854 FORMAT(12G10,3)
RK(I)=AMIN1(1.OO,RK(I))
COND( I)=RK( I )*,.sATcoN
C COND(I) =0.01* EXP(-5.69-2.059*-'ALOG(-POTM(I)*100.0))
C (CHOOSE BROOKS & COREY OR EXPONENTIAL, AS DATA INDICATES.)
85 CONTINUE
DO 110 I=2,NJJ
AVCOND(I)=.5*'(COND(I-1 )+COND(I))
FLW(I )=AVCOND( I)*(poTH(I-1 )-POTH( I)) /DIST( I)
110 CONTINUE
FLW(NJJ+1) =DRAINC
NFLW(NJJ+1) =DRAING
POTMAR = - AFCEN(SUTBX,SUTBY,THTAIR)
IF(POTM(1).CT. POTMAR)FLW(1)=-SLEVAP
IF(POTM(1).LE. POTMAR)FLW(1)=FLW(2)
DO 120 I=1,NJJ
NFLW( I)=FLW( I)-FLw( 1+1 )-RTEX( I)
120 CONTINUE
DO 62 I1=19NJJ
VOLW(I =INTCRL (VOLw(I) ,NFLW(I),DELT)
62 CONTINUE
C*
C
C
C
W=AMAX1(O0,,(POTM(2)-ExTMIN))
DO 1010 I=1,NNJ
X=AMAX1(0 .0, (POTM(I )-BRMIN))
XX=AMAX1(0.0, (POTM(I)-ExTMIN))
BIRTH(I)=(BR*,%(1.0-EXP(-AA*f'X**%fBB)))/('((DEPTH(I)*DEPTHC))**1'-.,)
EXTENS(I )=(ExTNRT*(l1.0O-EXP(-AA*'XX%-*BB) ) I((DEPTH (I )*-DEPTHC) )**1.)
IF (PRTL(I) LT, MINRTL* TCOM(I) EXTENS(I =0.
1010 CONTINUE
RTGRO(1=PRTL(1)*-BIRTH(1)* (1.0 - FRAC)* TMPFCR
SUMRC=RTCRO( 1)
DO 647 I=2,NNJ
RTGRO(I)=(PRTL(I-1)*f'EXTENS(I-1)+PRTL(I)*'BIRTH(I))*
(1.0 - FRAC) I TMPFCR
647 SUMRG=RTCRO( I)+SUMRG
SUMRTG=0 .0
nn(SURGO E.0T 0)COMOA64
[56]
DO 649 I=1,NNJ
RTDTH( I)=PRTL( I )*fDTHFAC*f'TMPF'CR
649 SUMRD=SUMRD+RTDTH( I)
SUMRTD=0 .0
DO 651 1=1, NNJ
IF(SUMRD.EQ.0.)GO TO 651
RTDTH( I)=RTDTH(lI)-*-ROOTDY/SUMRD*'LNCFAC
SUMRTD=SUMRTD+RTDTH (I)
651 CONTINUE
DO 653 1=1, NNJ
NETGRO( I)=RTCRO( I)-RTDTH( I)
IF' ( ROOTVL(I) .GT* POROS(1)*,,TCOM(I)) NETGRO(1Y0.*
NETWTC(I) = NETCRO(I) / LNCFAC
NETVLC(I) = NETWTC(I) If 100./ 
(RTDwPc*"1000.)
653 CONTINUE
NETGRO(NJ) = 0.
NETWTG(NJ) = 0.
NETVLG(NJ) = 0.
DO 63 I1=1, NNJ
PRTL(I) =INTGRL (PRTL(I),NETGRO(I),DELT)
ROOTWT(I) =INTCRL (ROOTWT(I) ,NETWTC(I) ,DELT)
ROOTVL(I) =INTGRL (ROOTVL(I) ,NETVLG(I) ,DELT)
63 CONTINUE
C
DO 102 I=1,NNJ
RSSL(I )=1. /(B'-coND(I )*'(pRTL(I )+NOTT(PRTL(I) )*fJ1 OE-20))
PTOTL( I)=POTH( I)
RRS(I )=URRs/(PRTL(I )+NOTT(PRTL(I ))-*1 .lOE-10)
ARS( I)=UARS*,,DEPTH( I) /(PRTL( I)+NOTT(PRTL( I) )*1 .lOE-20)
RSRT(I )=RRS(I )+ARs(I)
102 CONTINUE
C
CUMREM =INTCRL (CUMREM ,SUMR ,DELT)
COUNT=0 .0
115 CONTINUE
COUNT=COUNT+ 1.0
IF(COUNT.LT.100.0)CO TO 116
CO TO 165
116 CONTINUE
C
SUMR=0.0
DO 150 J=1,NNJ
I =J
RTEX(I )=AMAx1(0~, (POTH(I )-POTCR)/(RsSL(I )+RsRT(I )))
I vf(rUNS.C-T0CO TO I' f N n1 1-7
[57]
118 CONTINUE
C
IF(ABS(DIF).LE.ERROR)GO TO 165
C IF(DIF)160,165,160
160 POTCR=AMIN1((POTCR-DIF*-,POTCRIF'CF) ,MAXPOT)
CO TO 115
165 CONTINUE
DO 170 I=1 ,NNJ
POTRT( I)=POTCR+RTEX(lI)*,,RsRT( 1)
170 CONTINUE
C
DOUBLP = (POTCR-POTCRD)/DELAY
POTCRD =INTGRL( POTCRD ,DOUBLP ,DELT)
SINCLP = POTCRD
POTCRE=AMIN1 (POTCR, SINGLP)
C SINCLP IS A REAL*,,4 REPRESENTATION OF POTCRD, FOR THE AMINi FUNCTION
DO 67 I1=1, NNJ
CRTEX(I) =INTCRL (CRTEx(I) ,RTEX(I),DELT)
67 CONTINUE
C
EVAP=AMIN1 (-FLw( 1) ,SLEVAP)
CEVAP =INTCRL (CEVAP ,EVAP ,DELT)
DRAIN =INTCRL(DRAINDRAINC ,DELT)
FLW8N=-AMIN1(O.0,FLW(8))
CAPRIS =INTCRL (CAPRIS ,FLW8N ,DELT)
CTRAN =INTCRL (CTRAN ,TRANSP,DELT)
DRAINC=FLW(8)
C
C IF(YY .CT.0.1)CO TO 1200
C OUTDEL = OUTDEL + OUTDEL
C
1000 CONTINUE
1200 CONTINUE
C
TIME = TIME + DELT
RUNS =RUNS+ 1
C
IF (xxx.CT.1) CO TO 6001
WRITE(1,276) HOURS, (POTH(I) ,I=1,09)
276 FORMAT(1OE1O.3)
WRITE(2,276) HOURS, (NFLw(I) ,I=1 ,9)
WRITE(3,276) HOURS, HOUR, POTCRE, POTCR, SOLCHO, SHOOTW,
$ ROOTW, CTRAN, CEVAP, JULIAN
WRITE(4,276) HOURS, PHOTSN, GROWTH, RESP, ZZ1022,
$ SUMR, EV" T TAP,%r"TR1ANSD7t- V
[581
$ DROP , LFCL, RADCAL
WRITE(15,277) HOURS, MONTH, DATE, HOUR,WATRST,PHOTC,PHOTD,
$ PHOTSN,LAI,LFCL
WRITE(16,276) HOURS, (PRTL(I),I=1,9)
WRITE(17,276) HOURS, (ARS(I),I=1,9)
WRITE(18,276) HOURS, (RRS(I),I=1,9)
WRITE(6, 392) JULIAN,SHOOTW,ROOTW,LAI,ROOTL,PHOTSN,POTCR,TRANSP
WRITE(20, 392) JULIAN,SHOOTW,ROOTW,LAI,ROOTL,PHOTSN,POTCR,TRANSP
392 FORMAT(/' JULIAN=', F6.2,' 
SHOOTW=',F10.5,' ROOTW=',
$F10.5,' LAI=', F8.3,/' ROOTL=', F10.3,' PHOTSN=',E
0
.2,' POTCR
= '
,
$ F10.2,' TRANSP=',E10.2)
GO TO 6001
C
C
C
C * * * * * * * * * * * TERMINAL SEGMENT 
* * * * * * * * * * *
C
C
C TERMINAL SEGMENT OF MODEL
99 CONTINUE
WRITE(6, 591) HOUR, MONTH, DATE
591 FORMAT(//, ' FINISH CONDITION REACHED AT ', F4.1,
$ ' HOURS ON', 14, ' /', 12)
WRITE(6, 391) JULIAN,MAXRAD,RADN,LAI,WATRST,TIME,SOLCHO,POTCR
391 FORMAT(//,' JULIAN = ', F8.4, ' MAXRAD = ' F2.4, ' RADN
$F12.4, ' LAI = ', F8.3, ' WATRST = ', F10.3, //, 5X,
$ ' TIME= ',F10.2,' SOLCHO = ',F10.7,' POTCR = ',F10.2,
$ ' CUMREM',4X,' HOURS',5X,' XXX',6X,' YY')
STOP
END
C
FUNCTION INSW(FIRST,SECOND,THIRD)
REAL INSW
INSW = THIRD
IF (FIRST.LT.0.) INSW=SECOND
RETURN
END
C
FUNCTION IMPULS(FIRST,SECOND,THIRD)
REAL IMPULS
IMPULS = 0.00000
DO 10 I=1,10000
COUNT = SECOND + I*THIRD
IF (FIRST.LT.COUNT)GO TO 11
IF (FIRST.EQ.COUNT)GO TO 12
10 CONTINUE
12 CONTINUE
IMPULS = 1.
11 CONTINUE
RETURN
END
FUNCTION NOTT(INIT)
REAL*8 INIT
[59] .
REAL*4 NOTT
NOTT = 0.
IF (INIT .LE. 0) NOTT =1
RETURN
END
FUNCTION AND(LOWHIGH)
REAL LOW,HIGH
AND = 1.0
IF (LOW .LT. 0 .OR, HIGH
RETURN
END
*LT* 0) AND = 0.0
C
FUNCTION LIMIT( BOTTOM ,TOPSTART)
REAL LIMIT
LIMIT = START
IF (START.LT.BOTTOM) LIMIT= BOTTOM
IF (START.GT.TP) LIMIT = TOP
RETURN
END
FUNCTION AMOD(INPUT,INPUTD)
REAL INPUTINPUTD
AMOD = INPUT
DO 10 I=1,1000
IF (AMOD XT. INPUTD) AOD=
10 CONTINUE
RETURN
END
AMOD - INPUTD
FUNCTION ZHOLD(FIRST,INTEND,THIRD)
REAL INTEND
ZHOLD = FIRST
IF (INTEND .CT. 0.000001) ZHOLD=THIRD
RETURN
END
FUNCTION INTCRL(OLDVALDERIVDELT)
REAL*8 INTCRL,OLDVAL
INTCRL = OLDVAL + DERIV*DELT
RETURN
END
FUNCTION AFCEN(XVAL, YVAL, ARC)
REAL NEWX, NEWY, OLDX, OLDY
DIMENSION XVAL(1), YVAL(1)
OLDX = XVAL(1)
OLDY = YVAL(1)
DO 101 I = 2,400
NEWX = XVAL(I)
IF (ARC.LT.XVAL(I)) CO TO 102
OLDX = NEWX
101 CONTINUE
102 CONTINUE
[60]
c
c
c
c
IF (OLDX.EQ.NEWX) OLDX= OLDX -1.OE-1O
IF (OLDX.EQ.ARG) OLDX= OLDX -1.OE-10
NEWY = YVAL(I
OLDY = YVAL(I-1)
AFGEN = OLDY + ((NEWY-OLDY)/(NEwx-oLDx) (ARG-oLDx))
RETURN
END
C
SUBROUTINE MTIME(MONTHDATEJDAY)
INTEGER MONTH, DATE
INTEGER DAYS(13)
DATA DAYS /0,31 ,59,90,120, 151,181,212,243,273,304,334,365/
C CALENDAR--NUMBER OF DAYS AT END OF EACH MONTH
C (NOTE THAT FOR LEAP-YEARS, 1 MUST BE ADDED FOR FEB-DEC)
C
MONTH=(JDAY/29 )+1
J=JDAY-DAYS (MONTH)
IF(J.GE.1)GO TO 775
MONTH=MONTH- 1
J=JDAY-DAYS (MONTH)
775 CONTINUE
DATE = J
RETURN
END
C
SUBROUTINE DLYTOT(DTOTZDTOT,DTOTI ,RATE,TIME,DELT)
REAL IMPIMPULS
REAL*,,8 INTGRL, DTOTI
DTOTI = INTGRL(DTOTI,RATE,DELT)
IMP =IMPULS(TIME,DELT,86400.)
DUMMY = DTOTI
DTOTZ = ZHOLD(DTOTZ,IMP,DUMMY)
DTOT = DTOTI-DTOTZ
C
C THE ACCUMULATOR IS EMPTIED 
AFTER MIDNIGHT,
C SO CONTENTS ARE AVAILABLE FOR PRINTING.
RETURN
END
C
SUBROUTINE WAVE(TEMP,JULIAN,HOUR,MINT,MAXT,RISE,PI)
REAL MAXT ,MINT, JULIANINSW
TIMi = HOUR - 14.
TIM2 = HOUR + 10.
TIM = INSW(TIM1,TIM2,TIMI)
C- WTE(6,11)MTI ,TIIf1M2 , l T rIMHOUR% T
[611
13 FORMAT('TEMPSR=',G1O.2,'TEMPSS=',G1O.2,' VALAV=',G1O.2,' VALAMP=',
$ G10,2)
ANi = HOUR- RISE
AN2 = 14.- HOUR
AANNDD=-O.5 + AND(AN1,AN2)
TEMP=INSW(AANNDD ,TEMPSS,TEMPSR)
c WRITE(6,14) TEMPSR,TEMPSS,TEMP,AANNDD
14 FORMAT( TEMPSR=',IG1O.2,' TEMPSS='IG1O.2,' TEMP=',G1O.2,' AND=',
$ G1O,2)
RETURN
END
[62]
APPENDIX C:
ACSL-LISTING OF SIMULATION MODEL (VERSION 1.5)
' ****ADVANCED CONTINUOUS SIMULATION LANGUAGE****
' *** VERSION 1.5 *** '
PROGRAM WATER UPTAKE AND ROOT GROWTH IN A HOMOGENEOUS SOIL PROFILE
'CODED BY M.HUCK, D.HILLEL & G.HOOGENBOOM, AUBURN UNIVERSITY -OCT.,1982'
(NOW INCLUDES SEPARATE GROWTH AND MAINTENANCE RESPIRATION FACTORS)
AREA IS UNITY (M**2). UNITS SI (MKS).
ORGANIC MATTER PRODUCTION NORMALIZED TO 1 KG/M**2/YEAR
WHICH IS 10 GM/M**2/DAY OR 0.01 MG/M**2/SEC, ON AVERAGE
' FOLLOWING STATEMENT CHANGES INDEPENDENT VARIABLE TO TIME IN ACSL'
'CALL GSIZE(150.,11.0,1100)
VARIABLE TIME = 0.0
CINTERVAL CINT = 600.
NSTEPS NSTEP = 1
MINTERVAL MINT = 1.0
MAXTERVAL MAXT = 3600.
ALGORITHM IALG = 5
CONSTANT YY = 0.0
ARRAY CRTEX(10),RSRT(20), DIST(20), THETA(10), RRS(20), ARS(20)
ARRAY VOLW(10),FLW(20), COND(20) , AVCOND(20) , POTRT(20),IVOLW(10)
ARRAY POTH(20), POTM(20), RSSL(20), Y(20), SCAAL(20) ,IRTEX(10)
ARRAY NFLW(10),TCOM(10), RRL(10), SMIN(10), SMAX(10), ITHETA(10)
ARRAY PRTL(10),BIRTH(20), EXTENS(20), RTGRO(20), RTDTH(20)
ARRAY IPRTL(10),NETGRO(10),RTEX(10),PTOTL(20)
ARRAY LINE(101), RK(20), DEPTH(20)
INTEGER J,NJ,NJJ,I,LINE,IX,IB,IFUN,RUNS,IL,KEEP
CONSTANT IX=1H*,IB=1H ,KEEP=1,LINE(1)=1HI
CONSTANT SMAX = .35 , 4.50 , .004 , 2.0,+0.3E-7, 5.0E2,0.,0.,0.,0.
CONSTANT SMIN = .05 , -0.5 , 0.0 , -.1,-0.3E-7, 0.0,0.0,0.,0.,0.
' SCALE FACTORS 
FOR VERTICAL 
GRADIENT PLOTS
CONSTANT OUTF = 3.024E05
' OUTPUT FUNCTION FOR VERTICAL GRADIENT PLOTS MADE DURING EXECUTION -- '
' --INITIAL FREQUENCY FOR VERTICAL GRADIENT PLOTS IS INCREMENTED LATER'
' SPECIFICATION OF CONVERGENCE CRITERIA FOR VARIABLE TIME-STEP INTGRLS'
CONSTANT DAY = 0.0
CONSTANT ERROR = 0.01
CONSTANT CF = 0.10
' CORRECTION FACTOR AND ERROR PARAMETERS FOR ITERATIVE LOOP BELOW
' A STANDARD MATHEMATICAL CONSTANT
CONSTANT PI = 3.14
CONSTANT BCNDAY = 180.
CONSTANT CLOCK = 0.
' JULIAN DATE AT BEGINNING OF SIMULATION RUN
CONSTANT STEMP = 25.0
' TEMPERATURE OF THE SOIL, AS DEGREES C
CONSTANT RANCE = 5.0
[63]
' RANGE BETWEEN AVERAGE (REFT) TEMPERATURE AND MINIMUM OR MAXIMUM
CONSTANT REFT = 25.0
'THE MEAN TEMPERATURE, ABOUT WHICH SIMULATED TEMPERATURE OSCILLATES
CONSTANT MAXRAD = 700.
' INCOMING RADIATION
CONSTANT MAXFOT = 3.00E-06
' MAXIMUM PHOTOSYNTHETIC RATE
' ** INITIALIZATION OF PLANT-GROWTH PARAMETERS
CONSTANT IPER = 0.03
CONSTANT ISHOOT = 0.i, IROOT = 0.05
INITIAL SHOOT AND ROOT WEIGHTS, RESPECTIVELY (KG/M**2)
CONSTANT LNGFAC = 13000.0
LENGTH FACTOR, AS METERS OF ROOT PER KG ROOT WEIGHT
(A FACTOR OF 1000 CORRESPONDS TO ABOUT 1 MM ROOT DIAMETER)
CONSTANT RRL = 2.7E-01, 2.3E-01, 2.2E-01, 1.9E-01, 0.06,
.018, 1.OE-02, 1.OE-3, 1.OE-4, 1.0E-3
RELATIVE ROOT LENGTH (AS FRACTION OF TOTAL)
CONSTANT RSPFAC = 1.OE-07
' RESPIRATION FACTOR, CONVERTING UNITS AND PROPORTIONING
CONSTANT CONVRT = 0.30
' CONVERSION EFFICIENCY (MASS OF TISSUE PRODUCED PER GRAM INPI
CONSTANT FRG = 0.6666
' FRACTION OF CARBOHYDRATES GOING TOWARD SUPPORT OF SHOOT GROt
CONSTANT AGFAC = 3.0E-07
CONSTANT LEAFTH = 40.0
' LEAF THICKNESS--SQ. METERS LEAF AREA/SQ. METER SOIL, FOR 
EA(
' KG. SHOOT MASS ON THE SAME LAND AREA
CONSTANT GROFAC = 1.0E-05
CONSTANT DTHFAC = 1.0E-10
' FACTOR TO SCALE ROOT DEATH RATE
TABLE FRACTB,1,5/-500.,-200.,-050.,-10.,100.,...
0.05,0.25,0.70,0.95,0.95/
' UNITS = =, AS A FUNCTION OF CANOPY WATER POTENTIAL
TABLE DTHBGN,1,5/0.0,2.0,5.0,7.0,10.0,...
0.0,0.03,0.33,0.97,1.00/
UT)
WTH
CH
' ** INITIALIZATION OF WATER-BALANCE PARAMETERS
CONSTANT ITHETA = 0.0938, 0.1192, 0.1249, 0.1353, 0.1444, ...
0.1508, 0.1613, 0.1817, 0.2326, 0.3500
' INITIAL SOIL WATER CONTENT (VOLUME FRACTION)
' (INITIALIZED TO VALUES FOUND AFTER 12 DAYS OF DRAINING FROM
' SATURATION AT 20= WATER IN ALL LAYERS)
CONSTANT DTRDEM = 0.01
' DAILY TRANSPIRATION 
DEMAND, M/DAY
CONSTANT DLAY = 21600.
CONSTANT SATCON = 5.3348
' SATURATED CONDUCTIVITY, 
AS CM/DAY
CONSTANT ZLAM = 0.64762
Z(LAMBDA), AFTER LALIBERTE, BROOKS & COREY
CONSTANT TCOM = .10, 2 * .15 , 7 * .20
[64]
' THICKNESS OF EACH VERTICAL LAYER (COMPARTMENT), METERS
CONSTANT PB = 21.8258
' BUBBLING PRESSURE ( AIR ENTRY VALUE FOR TOP SOIL)
CONSTANT BRMIN = -0.30
CONSTANT EXTMIN = -1.00
' THRESHOLD POTENTIAL, THE DRIEST SOIL IN WHICH ROOT GROWTH CAN OCCUR
CONSTANT BR = 1.OE-10
CONSTANT EXTNRT = 3.OE-04
EXTENSION RATE, FOR NEW ROOT GROWTH 
FROM ONE LAYER INTO THE NEXT,
IN UNITS OF METER/SECOND
CONSTANT AA = 7.945089E-05, BB = 2.429255
' COEFFICIENTS FOR SIGMOID ROOT GENERATION CURVES
CONSTANT B = 1.0OE-02
' CONSTANT, RELATING ROOT CONDUCTIVITY TO ROOT LENGTH, AFTER (GARDNER)
CONSTANT URRS = 1.00E11
' UNITS FOR RADIAL RESISTANCE
CONSTANT UARS = 1.00E09
' UNITS FOR AXIAL RESISTANCE
CONSTANT MAXPOT = -2.0
' MAXIMUM ALLOWABLE CANOPY POTENTIAL,( -2 METER, OR -0.2 BAR)
TABLE SUCTB,1,12/0.025,0.05,0.075,0.10,0.15,0.20,0.25,0.30,0.35,...
0.40,0.45,0.50,...
20.,5.,3.,1.7,0.6,0.25,0.15,0.10,0.05,0.01,0.0,-1.00/
'TABLE WATRST,1,5/-500.,-200.,-100.,0.,100.,...
'0.05,0.05,0.95,1.0,1.0/'
' TRANSPIRATION TABLE FOR SENSITIVE CROPS SUCH AS MAIZE OR SOYBEANS
TABLE WATRST,1,7/-500.,-400.,-300.,-150.,-50.,0.,200.,...
0. 0.02,0.06,0.75,0.96,1.00,1.00/
TRANSPIRATION FOR DROUGHT-TOLERANT CROPS-EG. COTTON OR SORGHUM
TABLE AVPET,1,2/0.0,366.,0.01,0.01/
' MEASURED PAN EVAPORATION LOSSES - HERE ALL THE SAME TO CHECK MODEL'
TABLE LAIFAC,1,4/0.,3.0,6.0,10.,...
0.,0.5,0.9,0.95/
LEAF AREA INDEX FACTOR, PARTITIONS WATER LOSSS BETWEEN PLANT & SOIL
'* * * * * * * * * * INITIAL SEGMENT * * * * * * * * * 
* * * * * * * * '
INITIAL
RUNS = 0
FLPFLP = -1.0
JDAY = BGNDAY
ICHO ( ISHOOT + IROOT ) * IPER / ( 1. - IPER )
' INITIAL CARBOHYDRATES (KG/M**2), AS DECIMAL FRACTION OF TOTAL MASS.'
IRTL = IROOT * LNGFAC
' METER OF ROOT/SQUARE METER GROUND AREA AT INITIALIZATION
LAI = ISHOOT * LEAFTH
'LEAF AREA INDEX -- AREA OF LEAF SURFACE/UNIT LAND AREA
ETA = 2.0 + 3.0 * ZLAM
CONSTANT NJ = 10
' THE NUMBER OF LAYERS(J) IN THE SOIL PROFILE
DEPTH(1) = .5*(TCOM(1))
DIST(1) = DEPTH(1)
DO 20 I = 2,NJ
[65]
DIST(I) = .5*(TCOM(I-1)+TCOM(I))
DEPTH(I) = DEPTH(I-1) + DIST(I)
20..CONTINUE
853..FORMAT(/,' INITIALIZE',/,9X,'I',3X,'IPRTL',5X,'RSRT',8X,'IVOLW')
LINES(2)
WRITE(6,853)
DO 30 I = 1,NJ
IRTEX(I) = 0.0
IPRTL(I) = IRTL * RRL(I)
PARTIAL ROOT LENGTH, AT INITIALIZATION
IVOLW(I) = ITHETA(I)*TCOM(I)
INITIAL VOLUME OF WATER IN EACH SOIL LAYER
RRS(I) = URRS / IPRTL(I)
RADIAL RESISTANCE TO WATER FLOW IN THE ROOT
ARS(I) = UARS * DEPTH(I) / IPRTL(I)
AXIAL RESISTANCE -- ALONG THE XYLEM TRANSPORT SYSTEM
RSRT(I) = RRS(I) + ARS(I)
'RESISTANCE OF THE ROOTS
LINES(1)
WRITE(6,454) I,IPRTL(I),RSRT(I),IVOLW(I),TCOM(I),ITHETA(I),
IRTL, RRL(I), DEPTH(I)
454..FORMAT(3G10.3, 3F10.5, G10.3, 2F10.5, 3G10.3)
30..CONTINUE
POTCR = -20.000
POTCRD= -20.00
POTENTIAL OF THE CROWN (SHOOT), INITIALIZED BELOW DRIEST SOIL LAYER
(-20 METERS = -2 BARS)
DO 10 I = 2,101
10..LINE(I) = IB
INITIALIZES PRINT-LINE FOR VERTICAL PLOTS TO BLANK CHARACTER-STRING
NJJ = NJ+l
ONE MORE THAN THE NUMBER OF LAYERS IN THE SOIL PROFILE (NJ)
DO 15 I = 1,NJJ
15..FLW(I) = 0.0
' FLOW OF WATER PAST BOTTOM OF EACH LAYER, INITIALIZED TO 0.0
END$ ' INITIAL
' * * * * * * * * * DYNAMIC SEGMENT * * * * * * * * * * * * * * *
DYNAMIC
' *** DEFINITION OF TIME-BASES 
***
HOURC = TIME/3600.0
CUMULATIVE HOURS OF SIMULATION TIME
CLOCK = AMOD(HOURC,24.0)
CLOCK TIME, IN HOURS
DAY = HOURC / 24.00
JDAY = DAY + BGNDAY
[66]
JULIAN DATE, AS DECIMAL FRACTION, DURING THE SIMULATION
RUN = RUNS
CREATES A REAL-NUMBER COUNTING VARIABLE FOR PRINTER OUTPUT
DERIVATIVE
** ESTIMATION OF TEMPERATURE EFFECTS **
TMPFCS = 10.0 ** ((TEMP-REFT) * 0030103)
TMPFCR = 10.0 ** ((STEMP-REFT) * 0.030103)
BIOLOGICAL Q-10 -- DOUBLING REACTION RATE AT EACH 10 DEGREE TEMP CHNG'
TEMP = REFT + ((SIN(2 * PI * (DAY - 0.375))) * RANGE)
TEMPERATURE FACTOR, MULTIPLIER FOR TEMPERATURE EFFECT
RESERVE LEVELS AND TISSUE GROWTH
RESL = SOLCHO / (SOLCHO + ROOTW + SHOOTW)
RESERVE LEVEL, = FREE CARBOHYDRATE IN TISSUES
SOLCHO = INTEG((PHOTSN * PHTCAR - GROWTH - RESP),ICHO)
PHTCAR = 30. / 44.
SOLUBLE CARBOHYDRATES (FREELY MOBILE, AS METABOLIC RESERVES)
(KG/SQUARE METER)
GROWTH = TOPGRO + TOTRG
TOTAL GROWTH OF BOTH SHOOT AND ROOT SYSTEM
' ** PHOTOSYNTHETIC ACTIVITY **
PHOTSN = RADN * MAXFOT * LAIFAC(LAI) * WATRST(POTCR) / MAXRAD
PHOTOSYNTHETIC RATE (NET CARBON FIXATION, KG/SQUARE METER/SECOND
RADN = AMAXI( 0.0 , SIN(2 * PI * (DAY - 0.250))) * MAXRAD
ROOT AND SHOOT RESPIRATION
RESP = RESPSH + RESPRT
' TOTAL RESPIRATION, INCLUDING BOTH SHOOT AND ROOT SYSTEM
RESPSH = SHMRES + SHGRES
' RATE OF SHOOT RESPIRATION (KG/SQ METER/SEC)
' (SUM OF GROWTH RESPIRATION AND MAINTENANCE RESPIRATION)
SHMRES = SHOOTW * TMPFCS * RSPFAC
CSTMRS = INTEG( SHMRES,0.0)
' SHOOT MAINTENANCE RESPIRATION
SHGRES = TOPGRO * CONVRT
' SHOOT GROWTH RESPIRATION
RESPRT = RTMRES + RTGRES
' RESPIRATION OF ROOT SYSTEM
RTMRES = ROOTW * RSPFAC * TMPFCR
CRTMRS = INTEG(RTMRES,0.0)
' ROOT MAINTENANCE RESPIRATION
RTGRES = TOTRG*CONVRT
' ROOT GROWTH RESPIRATION, INCLUDING CHEMICAL CONVERSION AND TRANSPORT'
' ** GROWTH AND DEATH 
OF SHOOT TISSUE ** 
'
[67]
SHOOTW = INTEG( (TOPGRO - SHOOTD),ISHOOT)
' WEIGHT OF LIVING SHOOT TISSUE (KG/SQ METER)
POTCRD = INTEG((POTCR-POTCRD)/DLAY,10.)
DELAYED CANOPY WATER POTENTIAL
POTCRE = AMIN1(POTCR,POTCRD)
EFFECTIVE CANOPY WATER POTENTIAL
FRAC = FRACTB(POTCRE)
TOPGRO = TMPFCS * GROFAC * SOLCHO * FRAC
TOPGRO = TMPFCS * GROFAC * SOLCHO * FRG
RATE AS (KG/SQ METER/SEC) OF SHOOT (STEMS, LEAVES, AND FRUIT)
SHOOTD = SHOOTW * TMPFCS * DTHBGN(LAI) * AGING
SHOOT DEATH RATE (PRINCIPALLY LEAF-DROP DUE TO AGE AND WATER STRESS)'
AGING = AGFAC * (DAY/30.)
LAI = SHOOTW * LEAFTH
LEAF AREA INDEX, DIMENSIONLESS (AREA OF LEAF SURFACE/UNIT LAND AREA)'
GROWTH AND DEATH OF AGGREGATED ROOT SYSTEM *'
ROOTW = INTEG((TOTRG-ROOTDY),IROOT)
WEIGHT OF LIVE ROOT TISSUE(ALL SOIL LAYERS)
TOTRG = (1.0 - FRAC) * SOLCHO * GROFAC * TMPFCR
TOTRG = (1.0 - FRG) * SOLCHO * GROFAC * TMPFCR
TOTAL ROOT GROWTH, SUM OF ROOT WEIGHT IN ALL SOIL LAYERS
ROOTDY = ROOTW / RESL* DTHFAC * TMPFCR
RATE OF DYING FOR TOTAL ROOT SYSTEM-- MODULATED IN SUMMATION OF '
DEATH RATES FOR ROOTS IN EACH SOIL LAYER IN A LATER SECTION.
'INVERSELY PROPORTIONAL TO CARBOHYDRATE RESERVES--DYING OFF WHEN HUNGRY'
(RATE EXPRESSED AS KG ROOTS/SQUARE METER/SECOND -- WHOLE PLANT)
** TRANSPIRATION AND WATER 
LOSS FROM SOIL SURFACE **
TRANSP = WATRST(POTCR) * PET * LAIFAC(LAI)
' TRANSPIRATION LOSSES, AS METERS/SECOND
PET =AMAX1(0.01 * DTRDEM / 86400., PI * RADN * MPANEV / MAXRAD)
' POTENTIAL EVAPOTRANSPIRATION, BASED ON TEMPERATURE (+ RADIATION)
' (NOT LESS THAN 1= OF AVERAGE TRANSP. DEMAND--NEGATIVES ELIMINATED) '
CUMPET = INTEG(PET,0.0)
' CUMULATIVE POTENTIAL EVAPOTRANSPIRATION -- COMPARE OUTPUT WITH AVPET'
MPANEV = AVPET(JDAY) / 86400.
' MEASURED POTENTIAL EVAPOTRANSPIRATION IN FIELD (METERS PER DAY)
SLEVAP = PET * (1.0 - LAIFAC(LAI))
' SOIL EVAPORATION (METERS/SEC), PET REDUCED BY LEAF SHADING
' ** SOIL WATER MOVEMENT CALCULATIONS 
** '
VOLW = INTVC ( NFLW ,IVOLW)
' VOLUME OF WATER STORED IN EACH SOIL LAYER
[68]
OOMPUTE SOIL WATER CONTENT, POTENTIALS, AND CONDUCTIVITY
PROCEDURAL(THETA, POTM, POTH, MPOT, RK, COND
= TIME, PB)
DO 100 I = 1,NJ
THETA(I) = VOLW(I)/TCOM(I)
POTM(I)=-SUCTB(THETA(I))
POTH(I) =POTM(I) - DEPTH(I)
100..CONTINUE
** COMPUTE SOIL HYDRAULIC 
CONDUCTIVITY **
DO 85 I = 1i, NJ
MPOT = -POTM(I) * 100.0
IF (MPOT.LE. 0.0) GO TO 84
RK(I) = (PB/MPOT) ** ETA
RELATIVE CONDUCTIVITY (AS A FRACTION OF SATURATED CONDUCTIVITY)
CO TO 87
84..RK(I) = 1.0
' RELATIVE CONDUCTIVITY CAN NEVER BE MORE THAN 1.0;
' THUS, SATURATED CONDUCTIVITY APPLIES IF MATRIC POTENTIAL IS POSITIVE
87..CONTINUE
RK(I) = AMIN1(1.00, RK(I))
' CONDUCTIVITY IS LIMITED TO A MAXIMUM OF THE SATURATED CONDUCTIVITY
COND(I) = RK(I) * SATCON / 8.6400E06
' SOIL HYDRAULIC CONDUCTIVITY, METERS/SECOND
85..CONTINUE
END $ 'PROCEDURAL'
' ** COMPUTE VERTICAL SOIL WATER FLOW (DARCIAN) **
PROCEDURAL(AVCOND, FLW, NFLW= POTH)
DO 110 I = 2,NJ
AVCOND(I) = .5 * (COND(I-1) + COND(I))
FLW(I) = AVCOND(I) * (POTH(I-1)-POTH(I)) / DIST(I)
110..CONTINUE
IF (POTM(1) .GT. -10.0) FLW(1)=-SLEVAP
IF (POTM(1) .LE. -10.) FLW(1)=FLW(2)
' WATER FLOW OUT THE TOP IS LIMITED BY SUPPLY IF TOP LAYER IS DRY
FLW(NJJ) = 0.000000
DO 120 I = 1,NJ
NFLW(I) = FLW(I) - FLW(I+1) - RTEX(I)
120..CONTINUE
END $ 'PROCEDURAL'
' ** PARTITIONING AGGREGATE ROOT GROWTH BETWEEN SOIL 
LAYERS
PRTL = INTVC(NETGRO,IPRTL)
' PARTIAL ROOT LENGTH, IN EACH SOIL LAYER -- SUM OF GROWTH LESS DEATH
PROCEDURAL(BIRTH,EXTENS,RTCRO,SUMRG,RTDTH,SUMRD,NETGRO, ...
W,SUMRTG,SUMRTD = POTM)
[69]
.,., '
** ROOT GROWTH IN EACH LAYER
W = AMAX1(0.0, (POTM(2) - EXTMIN))
DO 1010 I=1,NJ
X = AMAX1(0.0, (POTM(I) - BRMIN))
XX = AMAX1(0.0, (POTM(I) - EXTMIN))
BIRTH(I) = BR * ( 1.0 - EXP ( -AA*X**BB ) )
1010..EXTENS(I) = EXTNRT * ( 1.0 - EXP ( -AA*XX**BB 
) )
RTGRO(1) = PRTL(1) * BIRTH(1)
SUMRG = RTGRO(1)
SUMMATION OF INSTANEOUS ROOT GROWTH RATES, OVER ALL SOIL LAYERS
(EXPRESSED AS METERS ROOTS/SQUARE METER SURFACE/SECOND)
DO 647 I = 2,NJ
RTGRO(I) = (PRTL(I-1)*EXTENS(I) + PRTL(I)*BIRTH(I))
GROWTH EXPRESSED AS METERS/SEC IN EACH SQUARE METER OF EACH 
LAYER
647..SUMRG = RTGRO(I) + SUMRG
TOTAL INCREASE, WHOLE PLANT, IN METERS/SQ. METER/SECOND
SUMRTG = 0.0
DO 648 I = 1,NJ
IF (SUMRG.EQ.0,00) GO TO 648
RTGRO(I) = RTGRO(I) * TOTRG/SUMRG * LNGFAC
(BRINGS ACTUAL ROOT GROWTH IN EACH LAYER INTO LINE WITH TOTAL
PHOTOSYNTHATE AVAILABLE AT ANY GIVEN TIME).
SUMRTG = SUMRTG + RTGRO(I)
648..CONTINUE
ROOT DEATH IN EACH LAYER ** '
SUMRD = 0.0
DO 649 I = 1, NJ
RTDTH(I) =PRTL(I) * DTHFAC * TMPFCR
ROOT DEATH, AS METERS/SECOND LOST FROM EACH LAYER
649..SUMRD = SUMRD + RTDTH(I)
SUMRTD = 0.0
DO 651 I = 1, NJ
IF (SUMRD.EQ.0.) GO TO 651
RTDTH(I) = RTDTH(I) * ROOTDY/SUMRD * LNGFAC
' SCALES ACTUAL DEATH RATE TO TOTAL AGGREGATE REQUIRED FOR C-BALANCE '
SUMRTD = SUMRTD + RTDTH(I)
' TOTAL FOR PLANT, AS METERS/SQ. METER/SECOND
651..CONTINUE
' ** SUMMARY OF GROWTH AND DEATH IN EACH 
LAYER *'
DO 653 I = 1,NJ
653. .NETGRO(I) = RTGRO(I) - RTDTH(I)
' NET CHANGE IN ROOT LENGTH, AS METERS/SECOND CHANGE IN EACH LAYER. '
END $ 'PROCEDURAL'
' ** ROOT SYSTEM RESISTANCE 
AND WATER UPTAKE ** '
PROCEDURAL(RSSL, PTOTL, RSRT = COND,SUMRG)
[70]
DO 102 I = 1,NJ
RSSL(I) = 1./(B*COND(I)*PRTL(I))
PTOTL(I) = POTH(I)
NOTE THAT PTOTL IS THE SAME AS HYDRAULIC POTENTIAL IN THIS VERSION
RRS(I) = URRS / PRTL(I)
RADIAL RESISTANCE TO WATER FLOW IN THE ROOT
ARS(I) = UARS * DEPTH(I) / PRTL(I)
AXIAL RESISTANCE -- ALONG THE XYLEM TRANSPORT SYSTEM
RSRT(I) = RRS(I) + ARS(I)
COMBINED AXIAL AND CONDUCTIVE RESISTANCE OF ROOTS IN THIS LAYER
102..CONTINUE
END $ 'PROCEDURAL'
** CALCULATION OF POTCR AND PARTITIONING OF ROOT WATER UPTAKE
CUMREM = INTEG(SUMR,0.0)
CUMULATIVE WATER REMOVAL (BY ROOT SYSTEM) FROM ALL SOIL LAYERS
PROCEDURAL( SUMR,DIFF,DIF,RTEX,POTRT
POTH, TRANSP, RUN, RSRT)
COUNT = 0.0
FLPFLP = -FLPFLP
115..CONTINUE
COUNT = COUNT + 1.0
IF ( COUNT .LT. 100.0 ) GO TO 116
GO TO 165
IN CASE THE LOOP DOES NOT CONVERGE IN 100 TRIES, GO AHEAD ANYWAY
116..CONTINUE
SUMR = 0.0
DO 150 J = 1,NJ
I = J
IF ( FLPFLP .EQ. 1.0 ) I = NJ - J + 1
RTEX(I) = AMAX1(0.0 ,(POTH(I) - POTCR) / (RSSL(I) + RSRT(I) ) )
ROOT EXTRACTION, M/SECOND
SUMR = SUMR + RTEX(I)
' SUM OF WATER REMOVALS BY ROOTS IN ALL LAYERS
DIFF = TRANSP - SUMR
IF (SUMR .LT. TRANSP) RTEX(I) = AMIN1(RTEX(I),DIFF)
150..CONTINUE
' FOR EACH LAYER, WATER EXTRACTION IS ASSUMED ON THE BASIS OF CURRENT '
' VALUE FOR CANOPY POTENTIAL. ITERATION WILL CONTINUE UNTIL EQUAL. '
DIF = (SUMR - TRANSP) / TRANSP
IF (COUNT.GT.5.0) GO TO 165
IF ( ABS(DIF) .LE. ERROR ) GO TO 165
IF ( DIF ) 160 , 165 , 160
' ADJUSTMENT OF CANOPY WATER POTENTIAL UP OR DOWN AS NEEDED TO BALANCE'
160..POTCR = AMIN1((POTCR - DIF*POTCR*CF),MAXPOT)
GO TO 115
165..CONTINUE
DO 170 I = 1,NJ
POTRT(I) 
= 
POTCR + RTEX(I) * RSRT(I)
170..CONTINUE
[71]
END $ 'PROCEDURAL'
SUMMARY OF WATER MOVEMENT AND EVAPORATIVE LOSSES
CRTEX = INTVC ( RTEX ,IRTEX)
CUMULATIVE ROOT EXTRACTION
EVAP = AMIN1(-FLW(1), SLEVAP)
EVAPORATION FROM SOIL SURFACE - LIMITED BY AVAILABILITY OF WATER
' (COMING FROM DEEPER SOIL LAYERS) OR BY THERMAL INSOLATION AT SURFACE
CEVAP = INTEG( EVAP,0.0)
CUMULATIVE EVAPORATION FROM SOIL SURFACE
FLW8P = AMAX1 (0.0,FLW(8))
DRAIN = INTEG (FLW8P,0.O)
INTERNAL DRAINAGE, AS WATER PASSES THE BOTTOM OF THE 7TH LAYER
FLW8N = - AMIN1(0.0,FLW(8))
CAPRIS = INTEG (FLW8N,0.0)
CAPILLARY RISE, PAST THE 8TH LAYER
CUMTRN = INTEG (TRANSP,0.0)
DRAING = FLW8P
CUMULATIVE TRANSPIRATION, AS M/SQUARE METER
XYZ=DEBUG(02,0.0)'
ZYX=DEBUG(01,3600.)'
END$'DERIVATIVE'
TERMT(HOURC.GT.120.0.OR.POTCR.LT.-300..OR.SOLCHO.LT.I.0E-07.OR....
SHOOTW.LT.0.0001.OR.TOPGRO.LT.-1.0E-10.OR.TOTRG.LT.-1.0E-18)
THE SIMULATION WILL TERMINATE WHEN THE PLANT WATER POTENTIAL DROPS'
' BELOW -300 METER WATER POTENTIAL(OR -30 BAR),OR WHENEVER ALL
SOLUBLE CARBOHYDRATE IS EXPENDED ( NO FOOD IN STORAGE)
** VERTICAL GRADIENT PLOTTING INSTRUCTIONS **
PROCEDURAL(YY,Y=OUTF,THETA,POTM,CRTEX,PTOTL,FLW,PRTL,TCOM)
YY = PULSE ( 0.0 , OUTF , 600. )
IF ( YY .EQ. 0.0 ) GO TO 1200
IF (TIME.LT.OUTF) GO TO 1200
IF (KEEP.NE.1) GO TO 1200
OUTF = OUTF + OUTF
RUNS = 1
COUNT = 1
' FOR VARIABLE-FREQUENCY OUTPUT PLOTS
DO 1000 IFUN = 1,6
' THE ORDER WILL BE THETA PPOTM CRTEX PTOTL FLW PRTL
GO TO ( 500,550,650,700,750,850 ) , IFUN
500..DO 505 I=1,NJ
505.. Y(I) = THETA(I)
WRITE(6,1505)
1505..FORMAT('1', /, 56X, 'THETA VS. DEPTH', /)
GO TO 900
550..DO 555 I=1,NJ
555..Y(I) = - POTM(I)
WRITE (6, 1555)
1555..FORMAT('1',/,56X,'-POTM (METERS) VS. DEPTH', /)
[72]
GO TO 900
650. .DO 655 I=1,NJ
655. .Y(I) = CRTEX(I)
WRITE(6,1655)
1655..FORMAT('1' ,/,56X, 'CUMULATIVE ROOT EXTRACTION, METERS VS. DEPTH',!)
GO TO 900
700. .DO 705 I1=1, NJ
705. .,Y(I) =-PTOTL(I)
WRITE(6, 1705)
1705..FORMAT('1',/,56X,'TOTAL WATER POTENTIAL AS A FUNCTION OF DEPTH',!)
GO TO 900
750. .DO 755 I1=1, NJ
755. .Y(I) = FLW(I)
WRITE(6, 1755)
1755..FORMAT('1',/, 56X, 'VERTICAL WATER FLUX RATE, POSITIVE DOWN',!)
GO TO 900
850. .DO 855 I=1,NJ
855. .Y(I) = PRTL(I)/TCOM(I)
WRITE(6,1855)
1855..FORMAT('1',/, 41X, 'PARTIAL ROOT LENGTH, METERS/SQ. 'METER ', o
'IN EACH LAYER', I
900. .CONTINUE
WRITE(6,905) HOURC, RUN, IFUN
905..FORMAT(3X,'TIME IS ',F06o2,' RUN ='9F8.01 , IFUN 19= e
12,0 //)
SCAAL (IFUN)= (SMAX(IFUN)- SMIN(IFUN))/ 75.0
DO 950 I = 1,NJ
IL = ( Y(I) - SMIN(IFUN))/ SCAAL(IFUN) + 2.0
IF (ILLE.2) IL =2
IF (IL .GE. 101) IL= 101
J = 0.5 + TCOM(I)* 100.0/ 4.0
LINE(IL) =IX
9220,j = J-1
IF (J) 931,931,925
925. .WRITE(6,926)
926. .FORMAT(' 1
Go TO 922
931..WRITE (6,935) DEPTH(I),(LINE(K),K=1,10,1), Y(I)
935. .FORMAT(2H , F9.4,3X,101A1,2X,E12.5)
LINE(IL) = B
950. .CONTINUE
1000. .CONTINUE
1200. .CONTINUE
RUNS = RUNS + 1
gmEND$I'PpROCRplAL'I
[731
PREPAR TIME,HOURC,RADNPOTGR,SOLGHO,SHOOTW,ROOTW,PHOTSN,POTCRE,...
TOPGRO,TOTRG,SHOOTD,ROOTDY,NETGRO,GUMREMCUMTRNCEVAPDRAIN,
RESP,FRAG,THETA,SHMRES,SHGRES,RTMRES,RTGRES
SET TITLE= ' WATER UPTAKE AND ROOT GROWTH IN A HOMOGENEOUS SOIL PROFILE'
OUTPUT TIME,HOURG,RADNPHOTSN, POTGR, SOLGHO, SHOOTW,00
ROOTW, 'NGIOUT'=1O
START
SET CALPLT=.TRUE.,PENGPL=.TRUE.,XINGPL=1O.OYINGPL=7.5,NPGGPL=50,
TTLGPL=.TRUE.,SYMCPL=.TRUE.
SET TITLE = ' NET-PHOTOSYNTHESIS AND RESPIRATION (KG/M2/SEG)
PLOT 'XAXIS' = HOURC,'XHI' = 120.,PHOTSN,RESP,'SAME',SOLGHO
SET TITLE = 'SHOOT MAINTENANGE AND GROWTH RESPIRATION
PLOT 'XAXIS' = HOURC,'XHI'=120.,SHGRESRTGRES,RTMRESSHMRES,'SAME'
SET TITLE = 'FAGTORS INFLUENGING BIOMASS PARTITIONING
PLOT 'XAXIS' = HOURC,'XHI'=120.,POTGR,POTGRE,'SAME',FRAG
SET TITLE = TISSUE GROWTH AND BIOMASS PARTITIONING
PLOT 'XAXIS' = HOURC,'XHI'=120.,TOPGRO,TOTRGSHOOTDROOTDY,'SAME'
SET TITLE = ' NET INGREASE IN ROOT LENGTH (METER/METER2)
PLOT 'XAXIS' = HOURG,'XHI'=120.,NETGRO(lO),NETGRO(9),NETGRO(8),...
NETGRO(7),NETGRO(6),NETGRO(5),NETGRO(4),NETGRO(3),NETGRO(2),...
NETGRO(1), 'SAME'
SET TITLE = 'SOIL WATER CONTENT
PLOT 'XAXIS' = HOURG,'XHI'=120.,THETA(04),THETA(3),THETA(2),...
THETA(1),THETA(10),THETA(9),THETA(08),THETA(7),THETA(6),...
THETA(5), 'SAME'
SET TITLE = ' SIMULATED CUMULATIVE WATER BALANGE TRANSPIRATION..
AND UPTAKE'
PLOT 'XAXIS'= HOURG,'XHI'=120.,CUMREM,GUMTRN,GEVAPDRAIN,'SAME'
STOP
[74]
10
1 I:
APPENDIX D
GLOSSARY OF TERMS USED IN SIMULATION MODEL
VARIABLE DESCRIPTION UNIT
AA Coefficient for sigmoid root generation curve
AAA Procedure statement
ABS FORTRAN function - absolute value
ABSERR Absolute error (CSMP variable for integration
control)
AFGEN CSMP function generator (CSMP library
linear interpolation)
AGE Cumulative days of simulation time
AGFAC Aging factor, parameter controlling leaf
aging
AGING Relative aging factor, modifying shoot
death rate
ALPHA Constant in relative conductivity
equation
ALOG FORTRAN function - natural logarithm
AMAX1 FORTRAN function - maximum real number
variable
AMIN1 FORTRAN function - minimum real number
variable
AMOD FORTRAN function - remaindering function
AND CSMP function - logic AND function
ARS Axial resistance to water flow through roots
(xylem flow resistance)
ATAN FORTRAN function - ARCTANGENT
AVCOND Average conductivity for water flow between
soil compartments
AVPET Average potential evapotranspiration, as
measured daily
B Constant, relating soil-root conductivity
to length of root
BB Coefficient for sigmoid generation curve
BGNDAY Julian date at the beginning of the
simulation run
BIRTH Branching rate (Formation of new roots
in same soil layer)
BR Branching rate parameter
BRMIN Lowest soil water potential at which root
branching occurs (new root tissue)
BULKDS Bulk density of the soil
BULKF Table for bulk density as a function of
depth
(dimensionless)
day
kg/(kg s)
day/day
1/m
sec
m/sec
m/day
1/m
day
m/sec
m/sec
m (kPa*10)
kg/m
3
[75]
CAPRIS Cumulative capillary rise (past the bottom
layer)
CEVAP Cumulative evaporation from soil surface
CF Correction factor - iteration loop
CLOCK Clock time
CMRAIN Measured daily rainfall
COND Soil hydraulic conductivity
CONVRT Relative growth efficiency
(kg biomass/kg carbohydrate respired)
COS FORTRAN function - cosine
COUNT Counter for iteration loop
CRC Current radiation under a clear sky
CRO Current radiation under an overcast sky
CRTEX Cumulative root extraction
CRTMRS Cumulative root maintenance respiration
CSDC Cosine of declination
CSLT Cosine of latitude
CSTMRS Cumulative shoot maintenance respiration
CTRAN Cumulative transpiration
CUMPET Cumulative potential evapotranspiration
CUMRAD Cumulative daily total radiation
CUMREM Cumulative water removal ( by root system )
from all soil layers
CO Auxiliary variable for the calculation of
photosynthesis under a clear sky
Cl Auxiliary variable for the calculation of
photosynthesis 
under a clear 
sky
C2 Auxiliary variable for the calculation of
photosynthesis under a clear sky
DATA FORTRAN statement - data input
DAY Day of the year during simulation
DAYRAD Daily total radiation
DAYRAI Daily total rainfall
DAYS Table for number of days per month
DEBUG CSMP statement - controls 
error debugging
DEC Declination of the sun with respect to the
equator
DELAY Delay time for computation of effective
canopy water potential
DELMAX Maximum time-step for integration routine
DELMIN Minimum time-step for integration
DELT Timestep for integration
DEPTH Depth to midpoint of soil layer, measured
from soil surface
DEPTHG Factor accounting for increased resistance
to soluble carbohydrates with deeper roots
DFCLTB Table for diffuse visible radiation under
a standard clear sky
DFOVTB Table for diffuse visible radiation under a
standard overcast sky
DIF Difference between root extraction rate and
transpiration rate
m
m
m/day
m/sec
kg/kg
Joule/(m
2 
sec)
Joule/(m
2 
sec)
m
kg/m
2
kg/m
2
m (H
2
0)
m (H
2
0)
Joule/m
m (H
2
0)
kg CO2/(m
2 
sec)
kg CO2/(m
2 
sec)
kg CO2/(m
2 
sec)
day
Joule/(m
2 
day)
m/day
degree
sec
sec
sec
sec
m
m/m
m/sec
[76]
DIFCL Diffuse visible radiation under a standard
clear sky
DIFF Relative difference between root extraction
rate and transpiration rate
DIFON Diffuse near-infrared radiation under a
standard overcast sky
DIFOV Diffuse visible radiation under a
standard overcast sky
DIMENSION (FORTRAN-statement to define arrays)
DIST Distance of flow between two adjacent soil
layers
DKPHOT Dark respiration rate of the leaves
DLLA Leaf area of shaded leaves
DLYTOT MACRO for the computation of daily totals
DRAD Daily total calculated radiation
DRADI Inititial daily total calculated radiation
DRAIN Cumulative internal drainage (past bottom of
lowest soil layer)
DRAING Instantaneous drainage rate (past bottom of
lowest soil layer)
DRC Daily total global radiation under a clear
sky
DRCI Initial daily total global radiation under a
clear sky
DRCP Daily total global radiation under a clear
sky of previous day
DRO Daily total global radiation under an
overcast sky
DROI Initial daily total global radiation
under an overcast sky
DROP Daily total global radiation under an
overcast sky of previous day
DRYWT Total dry matter of the plant
DTBL Table of shoot death versus leaf area index
DTHBCN Relative shoot death rate
DTHFAC Relative root death rate
DTR Daily total global radiation measured
(constant over a day)
DTRDEM Daily transpiration demand (average,
parameter for minimum)
DTRR Daily total global radiation measured
ECON
EFF
ERROR
Base of natural logarithm , e
Efficiency of photosynthesis at light
compensation point
Maximum allowable error in iteration loop
(POTCR computation)
ETA Soil porosity
EVAP Evaporation from soil surface
EXP FORTRAN function - exponentiation
EXTENS Extension rate for root growth into the
next soil layer
EXTMIN Threshold soil water potential for root
extension into next soil layer
EXTNRT Extension rate parameter, for root growth
into adjacent layer
Joule/(m
2 
sec)
(dimensionless)
Joule/(m
2 
sec)
Joule/(m
2 
sec)
m
k5/(m
2 
sec)
m 
/m
2
Joule/m
2
Joule/m
2
m
m/sec
Joule/m
2
Joule/m
2
Joule/m
2
Joule/m
2
joule/m
2
joule/m
2
kg/m
2
kg/(kg sec)
kg/(kg sec)
Joule/(m
2 
day)
m/day
Joule/(m
2
day)
kg/(J s)
m3/m
3
m/sec
m/sec
m (kPa*10)
m/sec
[77]
FCL Fraction of the time that the sky is clear
FGLOAD CMSP Function - input for function generator
table
FINISH Conditions for termination of simulation run
FINT Extension coefficient for light in canopy
FINTIM Total duration of simulation run
FLPFLP Flipflop control statement for iteation loop
FLW Flow of water past bottom of each soil layer
FLWNJN Capillary rise ( Past the bottom soil layer,
negative flow up)
FOV Fraction of time that the sky is overcast
FRAC Fraction of carbohydrates remaining in the
shoot ( computed )
FRACTB Table for carbohydrate partitioning based
upon canopy water potential
FRG Set constant for fraction of carbohydrates
remaining in the shoot
GROFAC Relative consumption rate of reserves
GROWTH Total growth rate of both root and shoot
systems
HOUR
HOURS
HSUN
Clock time
Cumulative hours of simulation time
Height of the sun
I Index of soil layer (ordinal number)
IB Index for gradient plotting
ICHO Initial mass of carbohydrates
IFUN Index for gradient plotting
IDAY Age of the plant at start of simulation
IL Index for gradient plotting
IMPULS CSMP function - impuls generator
INSW CSMP function - input switch generator
INTLZ Procedure statement
IPER Initial fraction of soluble carbohydrates
IPRTL Initial root length per layer
IRFAC Minimum soil water potential to trigger
irrigation
IRMIN Minimum soil water potential to trigger
irrigation (same as IRFAC, but in m)
IROOT Initial root mass
IRQUAN Volume of water applied during irrigation
pulse
IRTL Initial total root length
IRTVL Initial total root volume
IRTWT Initial total root mass
ISHOOT Initial shoot mass
ITHETA Initial volumetric water content of the soil
IVOLW Initial amount of water in each layer
IX Index for gradient plotting
(dimensionless)
sec
m/sec
m
kg/kg
kg/(kg sec)
kg/(m
2
sec)
hour
hour
degree
kg/m
2
day
m/m2
kPa
m
kg/m
2
cm3(m
2 
sec)
m 
/m2
kg/m
2
k 
/m
2
m3 
/m
2
[78]
J Index of soil layer (ordinal number)
JDAY Day of the year during simulation (integer
number)
JJ Day of the month during simulation
JULIAN Day of the year during simulation
K
KEEP
Runner in DO loop
CSMP integration control statement (0 =
trial integration, 1 = advance time step)
LAI Leaf area index
LAIFAC Leaf area index factor for partitioning
of water loss between plant and soil
LAITBL Table relating leaf area index and water loss
between plant and soil
LAT Latitude of experimental plot
LEAFTH Specific leaf area
LEAFW Mass of the leaves
LFCL Fraction of time that the sky is clear,
restrained between 0 and 1
LFOV Fraction of time that the sky is overcast,
restrained between 0 and 1
LIMIT CSMP function - defining limitation or
saturation of a system
LINE Variable for gradient plotting
LNGFAC Length/mass ratio of the roots
LSNHS Sine height of the sun of the previous day
MAXPOT Maximum allowable canopy water potential
MAXRAD Maximum light flux density ( during a day)
MAXSTM
MAXTEM
MAXTMP
MINRTL
MINSTM
MINTEM
MINTMP
MNSTMP
Measured maximum soil temperature
Measured maximum air temperature
Measured maximum air temperature table
Minimum root length for root expansion
between two adjacent soil layers
Measured minimum soil temperature
Measured minimum air temperature
Measured minimum air temperature table
Measured minimum soil temperature table
MONTH Integer number presentation of month
MPANEV Estimated pan evaporation (a scaling factor
for PET)
MPOT Matric potential of the soil in each layer
(computed from soil water content)
MTH Real number presentation of month
MTIME Macro for the computation of day and month
MXPHOT Maximum photosynthetic rate
MXSTMP Measured maximum soil temperature table
MU Constant 'm' in relative conductivity
equation
(dimensionless)
degree
m
2
/k
kg/m
(dimensionless)
(dimensionless)
m/kg
degree
m (MPa*10
2
)
J/(m
2 
sec)
degree(oC)
degree(oC)
m
degree('C)
degree(oC)
m/day
m (kPa*10)
kg/(m
2 
sec)
(dimensionless)
[791
day
day
day
NALARM CSMP flag
NETGRO Net change in root length per layer
( growth - death )
NETVLG Net change in root volume per layer
NETWTG Net change in root mass per layer
NFLW Net flow of water into each soil layer
( Darcian movement only )
NJ Number of layers comprising the soil
profile
NJJ Number of layers in the soil profile
plus one
NNJ Number of layers in the soil profile
minus one
NOT CSMP Function
NU Constant 'n' in relative conductivity
equation
OUTDEL Time interval for output points on CSMP plots
OUTF Output function for vertical gradient
plotting
00 Auxiliary variable to calculate
photosynthesis under an overcast sky
01 Auxiliary variable to calculate
photosynthesis under an overcast sky
02 Auxiliary variable to calculate
photosynthesis under an overcast sky
PARTDS Particle density
PB Bubbling pressure (air entry value for
saturated soil)
PET Potential evapotranspiration
PEV Measured pan evaporation table
PEVAP Measured pan evaporation
PEVV Measured pan evaporation
PEVVV Measured pan evaporation (constant over
a day)
PHOTC Photosynthetic rate under a completely
clear sky
PHOTD Photosynthetic rate under a completely
clear sky for diffuse radiation
PHOTS Photosynthetic rate under a completely
clear sky for direct radiation
PHOTSH Photosynthetic rate under a completely
overcast sky
PHOTSM Maximum daily photosynthetic rate (net
fixation)
PHOTSN Photosynthetic rate (net carbon fixation)
PHTCAR Photosynthetic carbon conversion factor
(molecular weight ratio)
PI Circumference of a circle, divided by its
diameter
POROS Porosity of the soil
POTCR Canopy plant water potential
POTCRD Delayed canopy water potential
m 4sec
m /sec
kg/sec
m/sec
r-
(dimensionless)
sec
sec
kg/(m
2 
sec)
kg/(m
2 
sec)
kg/(m
2 
sec)
kg/m
3
cm (kPa*10
-
)
m/sec
m/day
m/day
m/day
kg/(m
2 
sec)
kg/(m
2
sec)
kg/(m
2
kg/(m
2
sec)
sec)
kg/(m
2 
sec)
kg CO2 /(m
2 
sec)
22
(dimensionless)
m (MPa*10
-2
)
m
[80]
POTCRE Effective canopy water potential
POTH Hydraulic potential head in each soil layer
POTM Matric potential of the soil in each layer
POTMAR Minimum matric potential of top soil layer
POTRT Water potential of the roots
POVC Auxiliary variable to calculate photosynthesis
PRDEL Time interval for outputting print results
PROC1 Procedure statement
PROC2 Procedure statement
PROC3 Procedure statement
PROC4 Procedure statement
PROC5 Procedure statement
PRTL Root length per layer
PS Auxiliary variable for the calculation of
photosynthesis
PSH Auxiliary variable for the calculation of
photosynthesis
PTOTL Total soil water potential (gray. + osm. +
matric) for each soil layer
PULSIR Pulse to trigger irrigation after a defined
time interval
PULSSW Switch to trigger irrigation after soil water
potential has dropped below a minimum value
RAD 1 degree in radians (180/PI)
RADCAL Current global radaition
RADCPH Photosynthetic active radiation under a clear
sky
RADFCN Measured daily total global radiation table
RADIAT Total incoming radiation
RADN Radiation generating function
RADOPH Photosynthetic active radiation under an
overcast sky
RAIN Rainfall intensity
RANGE Range between average and minimum or
maximum air temperature
RANGES Range between average and minimum or maximum
soil temperature
REFT Reference or average air temperature
REFTS Reference or average soil temperature
RELERR CSMP statement - variable for integration
control
RESL Reserve level of carbohydrates in the plant
RESP Total respiration of both root and shoot
systems
RESPRT Total root respiration
RESPSH Total shoot respiration
RISE Time of sunrise
RISEI Initial value of sunrise
RK Relative soil conductivity
RNF Measured daily total rainfall table
RNFALL Measured daily total rainfall
ROOTDY Root death rate
ROOTL Total root length of living root tissue
m
m
m
m
m
sec
-oot-
m/m
2
(dimensionless)
(dimensionless)
m (kPa*10)
radians
Joule/(m
2
sec)
Joule/(m
2 
sec)
Joule/(m
2 
sec)
Joule/(m
2 
sec)
Joule/(m
2 
sec)
m/sec
degree(oC)
degree(oC)
degree(oC)
degree(oC)
kg/m
2
kg/(m
2
kg/(m
2
kg/(m
2
hour
hour
sec)
sec)
sec)
m/day
2
kg/ m
2 
sec)
m/m
[81]
ROOTVL
ROOTW
ROOTWT
RRL
RRLL
RRS
RSPFAC
RSRT
RSSL
RTDTH
RTDWPC
RTEX
RTCRES
RTGRO
RTMRES
RUN
RUNS
SATCON
SCALE
SHGRES
SHMRES
SHOOTD
SHOOTW
SIMDAY
SIN
SLEVAP
SLLA
SMAX
SMIN
SNDC
SNHS
SNHSS
SNLT
SOLCHO
SQRT
START
STEMP
STEMW
STORAGE
STWTR
SUMR
SUMRD
SUMRG
SUMRTD
SUMRTG
Volume of living root tissue (by layer)
Total mass of living root tissue
Mass of living root tissue (by layer)
Relative root length per layer
Relative root mass per layer
Radial resistance to root water uptake
Relative shoot maintenance respiration rate
Root system resistance to water flow, total
for each layer
Soil resistance to water flow, total for each
layer
Root death rate per layer
Percentage dry matter in the roots
Root extraction rate for soil moisture from
each layer
Root growth respiration
Root growth rate per soil layer
Root maintenance respiration rate
Real number counting variable for printer
output
Integer number counting variable for printer
output
Saturated conductivity m*10-2/day
Scale factor for vertical gradient plots
Shoot growth respiration rate kg/(m
2 
sec
Shoot maintenance respiration rate kg/(m
2 
sec
Shoot death rate kg/(m
2 
sec
Mass of living 
shoot tissue 
kg/m
2
Calendar day for input date day
FORTRAN sine function
Soil evaporation rate mnsec
Sun lit leaf area index 
m /m
2
Scaling factors for verticle gradient plotting -
Scaling factors for vertical gradient plotting -
Sine declination of the sun (dimension
Sine of height of sun, but zero when sun below
horizon (dimension
Sine of height of sun, also when negative (dimension
Sine of latitude of experimental plot (dimension
Soluble carbohydrate reserves (starch) in the
plant 
kg/m
2
FORTRAN function - square root
Beginning day for simulation run day
Temperature of the soil degree(oC)
Mass of the stem kg
CSMP statement - allocation of memory locations -
Fraction of shoot dry matter, partitioned into
the stem
Sum of water removal by roots in all layers m
Estimated root death rate for the whole plant m/(m
2 
sec)
Estimated root grwoth rate for the whole plant m/(m
2 
sec)
Corrected root death rate for the whole plant m/(m
2 
sec)
Corrected root growth rate for the whole plant m/(m
2
sec)
)
)
)
less)
less)
Less)
less)
[82]
m
3
/m
2
kg/m
2
kg/m
2
(dimensionless)
gram/m
sec
kg/(kg sec)
sec m/m
sec m/m
m/sec
(dimensionless)
m/sec
kg/(m
2 
sec)
m/sec
kg/(m
2 
sec)
_ssue(by -
>t tiss-
SUNDCL Direct visible radiation under a standard
clear sky
SUNTB Direct visible radiation under a standard
clear sky table
SUTB Suction table (volumetric water content
versus soil suction, in meter (kPa*10))
T Real number representation for month
TCOM Thickness of a soil layer (vertical direction)
TEMP Temperature of the air
THETA Volumetric water content of each soil layer
THTAIR Minimum volumetric water content of top soil
layer
TIME CSMP variable for simulation, initiating
starting time
TITLE CSMP-statement
TMPFCR Biological Q
10
-value - temperature factor for
the roots
TMPFCS Biological Q
10
-value - temperature factor for
the shoot
TOPGRO Total growth of the shoot system
TOTRG Total growth of the root system
TRANSP Transpiration loss
TRNTBL Transpiration table
TT Integer number representation for month
UARS Unit axial resistance per unit root surface
UPDATE Name of FORTRAN program generated to update
integration
URRS Unit radial resistance per unit root surface
VOLW Voume of water in each compartment
W Water potential difference for extension of
new roots in second soil layer
WATER Measured daily total rainfall (constant over
a day)
WATRST Water stress in plant tissue (relative 0 - 1
factor, based on canopy water potential)
WAVE Macro for the computation of temperature along
sine profile
Joule/(m
2
day)
m
d gr e(o C)
/m 
e
m3/m
3
sec
(dimensionless)
(dimensionless)
kg/(m
2 
sec)
kg/(m
2 
sec)
m/sec
sec m/m
sec m2
3mm /M
m (kPa*10)
m/day
(dimensionless)
Water potential difference for branching rate
of new roots
Auxiliary variable to calculate
photosynthesis (fraction overcast)
Auxiliary variable to calculate
photosynthesis
Auxiliary variable to calculate
photosynthesis (fraction sunshine)
Water potential difference for extension of
new roots
Vertical gradient plotting variable
Runner for vertical gradient plotting
m (kPa*10)
(dimensionless)
(dimensionless)
(dimensionless)
m (kPa*lO)
[83]
x
XOVC
XS
XSH
XX
Y
YY
CSMP function - storing integration value
Z(lambda), parameter to compute soil
hydraulic conductivity
Debug statement argument
Debug statement argument
Debug statement argument
(dimensionless)
ZHOLD
ZLAM
ZYX
ZYY
ZZZ