Progress Report Series No. 91
Agricultural Experiment Station
AUBURN UNIVERSITY
February, 1969
E. V. Smith, Director
Auburn, Alabama
SOIL FERTILITY EXPERIMENTS
WITH PEANUTS IN 1968
DALLAS HARTZOG and FRED ADAMS, Department of Agronomy 
and Soils
THE COOPERATIVE RESEARCH PROGRAM which was
begun in 1967 between farmers and Auburn Univer-
sity to better define soil fertility requirements 
of
peanuts and to improve correlation between ferti-
lizer requirements and soil-test values was continued
in 1968. The cooperation of several county Exten-
sion personnel contributed to the success of the
program.
Thirty-three experiments were conducted in 1968
in 4 counties (Covington, Geneva, Henry, and Hous-
ton). Twenty-three experiments were harvested (18
in Geneva, 3 in Houston and 1 each in Covington
and Henry).
The experimental area on each farm was divided
into either 8 or 12 plots, each plot being 4 rows
wide and 100 feet long. Each farmer fertilized,
planted, cultivated, dusted, and harvested peanuts
within all plots the same as those in the remainder
of his field. Four plots of each experiment received
no additional treatment; the remaining plots received
one of the following treatments: (1) a complete
fertilizer, (2) potassium, (3) calcium, (4) mag-
nesium, (5) zinc, or (6) boron.
FERTILIZER-RATE EXPERIMENTS
Residual versus direct application. Three experi-
ments were conducted to determine if fertilizer
should be applied directly to peanuts when peanuts
were following a crop that had been amply fertilized.
Corn was the preceding crop in all 3 experiments.
The experimental fertilizer used within the test area
was the same as that used by the farmer on the rest
of his field. It was drilled at planting by the farmer
on 4 of the experimental plots; the other 4 plots
received no fertilizer. One experiment was with the
Florigiant variety and two were with the Early
Runner. All 3 soils tested "medium" in both P and
K. The results in Table 1 show a definite yield in-
crease for fertilizer in one experiment (Baxley farm),
a possible yield increase in a second experiment
TABLE 1. EFFECT OF FERTILIZER ON YIELD AND SMK OF EARLY RUNNER PEANUTS IN 1968
Farmer County Soil type
E. Grace' Geneva Ruston sandy loam
L. Cotton Geneva Norfolk sandy loam
H. Baxley Geneva Norfolk sandy loam
Geneva Norfolk sandy loam
Geneva Norfolk sandy loam
Per acre soil-test values Per 
acre
rate of
pnH P K farmer's
pH P K fertilizer
Lb. Lb. Lb.
Residual fertilizer experiment
5.7 27 (M) 67 (M) None
5.8 34 (M) 76 (M) None
5.1 32 (M) 110 (M) None
Broadcast fertilizer experiment
5.6 59 (H) 162 (H) 300 of
0-10-30
5.9 90 (H) 136 (H) 500 of
0-10-20
Per acre
rate of
experiment
fertilizer
Lb.
450 of
0-14-14
250 of
6-12-24
185 of
6-24-24
150 of
7-21-14
300 of
4-12-12
Yield per acre
No extra
fert.
Lb.
SMK
fert. No extra
fert.
Lb. Pct.
Extra
fert.
Pct.
2,080 2,130 68 66
2,780 2,890 69 68
2,230* 2,470* 60 59
2,520 2,500 69 67
1,770 1,720 69 67
Florigiant variety; per cent "extra-large-kernel" was 35 for "farmer's fertilizer" and 
33 for extra "experimental fertilizer."
* Yields in bold-face type indicate yields on fertilized plots were statistically greater than on unfertilized 
plots.
T. Seay
G. B. Register
TABLE 2. THE EFFECT OF EXTRA POTASSIUM AT RATE OF 50 POUNDS PER ACRE OF K (60 PouNDS K.O) ON YIELD AND PER CENT
SOUND MATURE KERNEL (SMK)oF PEANUTS IN 1968
Farmer County
A. Barnes
G. Crowley
J. D. Donaldson
G. Outlaw
E. A. Stewart
Soil type
Geneva .Orangeburg sandy loam
Houston Orangeburg sandy loam
Geneva Norfolk sandy loam
Geneva Norfolk sandy loam
Geneva Ruston sandy loam
Per acre
Soil-test rate of
K per acre farmer's
fertilizer
Lb. Lb.
144 (H) 275 of
0-10-20
130 (H) 250 of
6-24-24
102 (M) 400 of
2-6-12
136 (H) 200 of
0-10-30
84 (M) 250 of
0-10-20
Gypsum 
Yield
added No extra
K
Lb.
No 1,510
Yes 3,680
No 1,640
No 3,510
No 2,320
(Cotton farm), and no yield increase in the third
experiment (Grace farm).
Two rates of fertilizer. Two experiments compared
two rates of fertilizer applied directly to peanuts
without regard to fertilizer applied to the preceding
crop. Both soils tested "high" in P and K and
probably needed no fertilizer to produce maximum
yields in 1968. However, a maintenance application
of fertilizer is recommended. Frequently, farmers
add considerably more than the maintenance rate.
The lowest fertilizer rate on the Register farm was
a broadcast application of 500 lb. per acre of 0-10-20;
the lowest rate on the Seay farm was a broadcast
application of 150 lb. per acre of muriate of potash
plus 500 lb. per acre of basic slag. Neither of these
experiments was designed to determine if the broad-
cast application of fertilizer was necessary for maxi-
mum yield. They were intended to show that peanuts
growing on a soil testing "high" surely did not need
more than a broadcast maintenance fertilizer appli-
cation. One-half of the plots received additional
fertilizer in the drill at planting time; the other half
received only a broadcast fertilizer. The results in
Table 1 show that the additional fertilizer drilled at
planting time failed to increase either yields or per
cent SMK on either farm. The broadcast application
was ample fertilizer for maximum yield as well as
for maintenance of soil phosphorus and potassium.
Whereas fertilizer either had no effect on yield
or increased yield slightly, there appeared to be a
general trend toward lower SMK values at the
higher fertilizer rates. Lower SMK values would
offset the value of a slight yield increase from ferti-
lizer and, of course, decrease the value of harvested
nuts when there is no yield increase.
POTASSIUM (K) EXPERIMENTS
Since soils of the peanut area in Alabama are gen-
erally "low" to "medium" in soil K, a tendency has
developed to add a relatively high rate of K directly
to the peanut crop regardless of the soil-test K level.
The merit of this practice has not been adequately
determined. Because of the potentially detrimental
effect of high soil-K on available soil-Ca (so essential
for normal kernel development), these experiments
were designed to determine if higher rates of K
fertilizer would, in fact, reduce yield or per cent
SMK. Five of these experiments were harvested, and
Early Runner was the variety in each case.
Soils were selected that tested "medium" or "high"
in soil K and to which the farmer had fertilized his
peanuts with 40 to 50 lb. per acre of K (48 to 60 lb.
K
2
0) prior to or at planting time. The experimental
K was then topdressed over the row at a per acre
rate of 50 lb. (60 lb. K
2
0) soon after seedling emer-
gence. Furthermore, gypsum was not top-dressed
to supply extra Ca in 4 of the 5 experiments. Gypsum
would be expected to counteract any detrimental
effect caused by high K fertilizer.
The data in Table 2 show that yields ranged from
1,500 to 3,700 lb. per acre, and in no case was there
a yield increase or SMK increase from the extra K
fertilizer. Neither was there a particular disadvan-
tage. Although there appeared to be a slight trend
toward a yield reduction from the extra K, this trend
was far from being conclusive.
CALCIUM (Ca) EXPERIMENTS
Six experiments were harvested in which calcium
was applied as a topdressing at early blooming: five
at a rate of 1,000 lb. of gypsum per acre and one at
500 lb. (Either rate is considered to be in excess of
the amount needed for these soils). Soil-test Ca
ranged between 160 lb. per acre (low) and 464 lb.
per acre (high), and soil pH ranged between 5.0 and
5.9. Results of the calcium experiments are sum-
marized in Table 3.
The Early Runner variety was planted in 5 experi-
ments. Yield was increased by gypsum in only one
case. On soils testing "medium" or "high" 
in Ca,
SMK
No extra
K
Pct.
69
Extra
K
Pct.
70
per acre
Extra
K
Lb.
1,490
3,600
1,570
3,400
2,160
66 68
61 59
71 72
69 68
TABLE 3. THE EFFECT OF TOPDRESSING CALCIUMi AT RATE OF 1,000 POUNDS PER ACRE OF GYPSUM ON YIELD AND PER CENT SOUND
MATURE KERNEL (SMK) OF PEANUTS IN 1968
Soil type
Tifton sandy loam
Orangeburg sandy loam
Kalmia loamy sand
Norfolk sandy loam
Norfolk sandy loam
Houston Tifton fine sandy loam
Soil Soil-test Yield per
pH Ca per acre No Gypsum
Lb. Lb.
Early Runner variety
5.6 315 (M)
6.0 400 (H)
5.2 195 (L)
5.6 319 (M)
5.9 464 (H)
Florigiant variety
5.0 160 (L)
County
Covington
Geneva
Geneva
Geneva
Geneva
acre
Gypsum
Lb.
2,530
1,570
3,350*
3,090
2,290
2,840*
SMK
No Gypsum Gypsum
Pct. Pct.
65
69
68
68
69
65
70
69
66
68
55* 680
1 Experimental rate of gypsum was 500 lb./A.
Per cent extra-large-kernel was 26 for "no gypsum" and 34 for "gypsum" treatment.
* Yield and percentages SMK in bold-face type indicate yields on gypsum plots statistically greater than on non-gypsum plots.
there was no response to added gypsum. However,
on the L. Davis farm, which tested "low" in Ca
(195 lb. per acre), there was a 420-lb. per acre yield
increase from topdressing with gypsum.
The Florigiant variety was planted in one experi-
ment. It was on a soil that tested "low" in Ca (160
lb. per acre). Topdressing with gypsum increased
yield by 510 lb. per acre. Gypsum also increased
SMK by 13 per cent and "extra-large-kernels" by 8
per cent on this farm.
BORON (B) EXPERIMENTS
Three experiments with boron were harvested.
Data in Table 4 show that neither yield, SMK, nor
per cent "hollow-heart" was affected by boron ferti-
lizer in any of the 3 experiments.
Since "hollow-heart" is the visual symptom of B
deficiency in peanuts, the incidence of this physio-
logical disorder was measured in all other experi-
ments, as well as in the B-experiments. Although
1968 was considered to be an unusually dry year
and B deficiency has been reported to be worse dur-
ing droughts, there were few incidences of "hollow-
heart." In no case did "hollow-heart" exceed 1 per
cent of the sample.
Peanuts from each plot of every experiment was
sampled and checked for "hollow-heart." There was
no "hollow-heart" on any plot where soil-test B was
more than 0.14 lb. per acre. Seven experiments had
soil-test B levels of 0.14 lb. per acre or less, and the
incidence of "hollow-heart" for each of these "low"
boron soils, along with soil-test B levels, are listed
in Table 5. Where application of boron was made
TABLE 4. THE EFFECT OF BORON APPLIED AT RATE OF 1 POUND PER ACRE OF B ON YIELD, PER CENT SOUND MATURE KERNEL (SMK),
AND PER CENT HOLLOW-HEART OF PEANUTS IN 1968
Soil-testYield 
per acre
B per acre No 
Added
B B
Lb. Lb.
No
B
Pct.Lb.
SMK
Added
B
Pct.
Hollow-heart
No Added
B B
Pct. Pct.
M. L. Burch Geneva Norfolk sandy loam 0.20 3,340 3,190 72 70 0.0
T. Davis Geneva Norfolk fine sandy loam 0.16 2,930 2,910 65 64 0.0
L. Davis
1  
Geneva Kalmia loamy sand 0.10 2,930 3,200 68 67 0.0
1 General peanut field was dusted by airplane with B containing fungicide, which probably drifted onto experimental area.
TABLE 5. THE OCCURRENCE OF "HOLLOW-HEART" IN ALL EXPERIMENTS WITH SOIL-TEST B OF 0.14 LB. PER ACRE OR LESS
Soil type
Tifton fine sandy loam
Norfolk sandy loam
Percentages of
plots with
"hollow-heart"
Pct.
Florigiant variety
8
37.5
Early Runner variety
Boron Soil-test Soil-test Soil
added B per acre Ca per acre pH
Lb.
Yes
No
0.14
0.12
E. A. Stewart Ruston sandy loam 0 Yes 0.14 z
L. Cotton Norfolk sandy loam 0 Yes 0.14
H. Anderson Tifton sandy loam 50 No 0.14
A. Barnes Orangeburg sandy loam 33 No 0.11
L. Davis Kalmia loamy sand 0 Yes' 0.10
1 Probably supplied B through drift from airplane-applied B-containing fungicide to remainder of peanut field.
Lb.
160
464
5.0
5.8
6.0
5.8
5.6
6.0
5.2
470
452
315
848
195
Farmer
H.
A.
L.
T.
G.
2,570
1,510
2,930*
2,930
2,410
2,380*
Anderson
Barnes
Davis
Davis'
B. Register
C. Hughes2
Farmer County Soil type
Farmer
C. Hughes
J. Hardwick
0.0
0.0
0.0
TABLE 6. THE EFFECT OF ADDING MAGNESIUM SULFATE AT THE RATE OF 20 POUNDS PER ACRE OF MG ON YIELD, PER CENT SOUND
MATURE KERNELS (SMK), AND EXTRA LARGE KERNELS (ELK) OF PEANUTS IN 1968
Farmer County
Soil type
Soil-test
Mg per acre No Mg
Lb.
J. Hardwick Henry Norfolk sandy loam 54 (H)
C. Hughes Houston Tifton fine sandy loam 15 (L)
* Yields and percentages in bold-face type 
are statistically differeni
by the farmer, there was no occurrence 
of "hollow-
heart"; where no boron was added 
to these "low"
boron soils, "hollow-heart" occurred 
in each case.
The only exception to this was a single 
plot (out of
12) on the Hughes farm. The soil boron 
levels that
resulted in "hollow-heart" in 1968 agree very closely
with the results found in 1967 on similar 
experiments.
Since the availability of soil B has been 
reported
to be affected by the level of soil Ca and soil pH,
these values have been included in Table 5. In these
experiments, however, there appears to have been
no relationship between B deficiency and either soil
Ca or soil pH.
MAGNESIUM (Mg) EXPERIMENTS
Two experiments with magnesium were harvested,
both with the Florigiant variety, one in Houston and
one in Henry County. Magnesium sulfate was used
as a topdressing in the row soon after planting at
the rate of 20 lb. per acre of Mg. The Mg level was
"high" (54 lb. per acre) on one soil and "low" (15 lb.
per acre) on the other soil. Results of the Mg experi-
ments are summarized in Table 6 and show that
the extra Mg did not increase yield but tended to
reduce both SMK and extra-large-kernel (ELK) per-
centages. The experiment on the Hughes farm
showed a reduction in yield where Mg was added.
This soil was "low" in Ca, had a soil pH of only
5.0, and gypsum was not added to correct Ca de-
Yield
Lb.
1,590
2,330*
Added
Mg
Lb.
1,660
1,890*
SMK ELK
No Mg Added 
No Mg Added
Mg Mg
Pct. Pct. Pct. Pct.
67 65 27 23
55* 50* 26* 19*
ficiency. Extra Mg might be expected to reduce
yields under these conditions because it lowers Ca
availability and aggravates Ca deficiency.
ZINC (Zn) EXPERIMENTS
Two experiments were harvested in which zinc
was applied as a topdressing in the row soon after
seedling emergence at the rate of 10 lb. per acre of
zinc sulfate. Both were conducted in Geneva County
on Norfolk sandy loam soils. Relatively high yields
were obtained in both experiments, and zinc ferti-
lizer had no effect on yield or quality of nuts,
Table 7.
SUMMARY
Results of experiments in 1968 showed a few re-
sponses to fertilizer treatments. A complete ferti-
lizer increased yield in one out of 3 experiments;
extra potassium tended to decrease yield but this was
not conclusive; gypsum increased yield on 2 soils
"low" in calcium but did not on 4 soils testing
"medium" or "high"; 
"hollow-heart" (B 
deficiency)
occurred on soils "low" in soil B and not fertilized
with boron; magnesium fertilizer was detrimental
in one out of two experiments; zinc fertilizer was
without effect.
Similar experiments on farmer's fields are planned
for 1969 in the continuing effort to improve the basis
for fertilizing peanuts.
TABLE 7. THE EFFECT OF ZINC APPLIED AT RATE OF 10 POUNDS PER ACRE OF ZINC SULFATE ON YIELD AND PER CENT SOUND MATURE
KERNEL (SMK) OF PEANUTS IN 1968
Farmer County Soil type
E. Baxley Geneva Norfolk sandy loam
L. Cotton Geneva Norfolk sandy loam
Yield per acre
Soil-test
Zn per acre
Lb.
2.5
5.0
No Zn
Lb.
2,510
2,650
Added
Zn
Lb.
2,570
2,710
SMK
No Zn
Pct.
60
67
Added
Zn
Pct.
59
69