Fertilizers for Johnsongrass on Calcareous Black Belt Soils :~~pi~ -*L~ AGRIC ULTURPAL EXPERIMENT STATION AUBURN UNIVERSITY Auburn, Alabamo E. V. Smith, Director CONTENTS Page METHODS 4-----------------NITROGEN AND LEGUME NITROGEN, COMMERCIAL 1958-61-4 RATES AND SOURCES OF NITROGEN, 1962-66 --------------- 5 10 11 N itrates in Johnsongrass ------------------------------ RATES OF PHOSPHORUS AND POTASSIUM, 1963-67 ------------- RATES OF NITROGEN, AND MAGNESIUM, PHOSPHORUS, POTASSIUM, 1965-70 ----------------------------- 12 SUMMARY AND CONCLUSIONS ----------------------- 13 FIRST PRINTING 4M, APRIL 1971 FERTILIZERS FOR JOHNSONGRASS ON CALCAREOUS BLACK BELT SOILS C. E. SCARSBROOK, C. E. EVANS, HAROLD GRIMES, R. D. ROUSE, and L. A. SMITH JOHNSONGRAss"One man's junk is another man's treasure." In row halepense (L.) Pers) is an example of the old adage, (Sorghum crops this grass is considered a noxious weed. At the other extreme, it is recognized as a valuable hay and temporary grazing crop in the Black Belt region of Alabama where it is widely grown in grassland systems. Persistence of johnsongrass as a weed is deceptive since it is extremely responsive to fertilizers and the stand can be depleted quickly by improper management. 2 Johnsongrass grows both from seed and from rhizomes produced the previous year. The rhizomes that will produce the next year's crop emerge from the crown beginning about flowering time. If the grass is cut before these new rhizomes are produced there will be no rhizomes for the next year's crop. The rhizomes live for only about 1 year. A common practice for ensuring sufficient rhizomes for the next year's growth is to make the last cutting in August or early September, which leaves sufficient time for new rhizomes to be produced before frost. After frost the dead grass can be grazed or cut for hay without affecting the rhizomes. There is little published information on fertilizers for johnsongrass. The research reported here was conducted to determine Respectively, Professor, Department of Agronomy and Soils; Associate Professor, Department of Agronomy and Soils; Assistant Superintendent, Black Belt Substation; Associate Director, Agricultural Experiment Station, and Assistant Dean, School of Agriculture; and Superintendent, Black Belt Substation. 2 BENNETT, HUGH W. AND N. C. MERWINE. 1964. Interplanted Legumes in Johnsongrass. Miss. Agr. Exp. Sta. Bull. 698. 4 ALABAMA AGRICULTURAL EXPERIMENT STATION the effects of rates of fertilizer elements on growth of johnsongrass in the Black Belt region of Alabama. METHODS The experiments were conducted on Sumter clay soil at the Black Belt Substation. These soils contain 40 to 60 per cent calcium carbonate and have a pH above 7. The soil test values for the experimental locations were low for phosphorus (P) and medium for potassium (K).3 All experiments were located on established stands in a johnsongrass meadow. Each location was overseeded when the experiment was begun. Fertilizers were applied on the soil surface. One-half the nitrogen (N) was applied before growth began in the spring and the remainder after the first harvest. Phosphorus, potassium, and magnesium (Mg) were applied in a single application before growth began in the spring except as indicated for K. Ammonium nitrate was the source of N unless otherwise stated. Superphosphate was the source of P, muriate of potash was the source of K, and magnesium sulfate was the source of Mg. Total N in the grass was determined by the Kjeldahl procedure and nitrates by the phenoldisulfonic acid method. All yields are reported as oven-dried forage. To convert to the approximate hay yields, about 10 per cent should be added to the oven-dry weights. Harvesting was done when the most advanced plots were in the blossom stage. In most years there were four harvests. COMMERCIAL NITROGEN AND LEGUME NITROGEN, 1958-61 One treatment received no P and K and all others received 108 pounds of P and 196 pounds of K per acre. Rates of N up to 320 pounds per acre were applied both with and without Caley peas (Lathyrus hirsutus L.) in a rotation. Where Caley peas were in the rotation, yield of the legume was added to that of johnsongrass. Irrespective of N treatment the Caley peas yielded an average of about 1/2 ton per year. ' Values for P can be converted to P 20 5 by multiplying by 2.3 and K to K20 by multiplying by 1.2. FERTILIZER FOR JOHNSONGRASS 5 Yield,lb/acre 14,000 2,000__ 10,000- - - O---- Johnsongross alone Johnsongross+ Coley peon 8,000 s - 6,000 4,000 0 40 80 10 160 200 240 280 32 Nitrogen applied each year-lb/acre FIG. 1. Effect of nitrogen on yield of johrsongrass alone and Caley peas, 1958-61, is illustrated here. jvhnsongrass plus Yields xxere increased wxith ev ery increment of N ont the grass alone or wxhen grown wixitb Caley peas, Figure 1. The add~ition of Caley peas resulted in igher y ieldls xxhere less than ab~out 200 pound~s ot iN wxas applied1. The highest x ields wxere ab~out 61 xxhere :320 poundls of N xxas applied. Hoxx cr, such high rates appear to he uneconomical. _tons There wxas a progressix c ioss of stand each xear oin plots receixing no PK. This rested( in decliningyilswecoprdt treatments that receixved the same rate of N (160 pound~s per acre ) plus P and K, Figure 2. After 4 y ears of cropping, the stand1 on the uo PK treatment xxas less than halt that of p)lots receixving a complete fertilizer. RATES AND SOURCES OF NITROGEN, 1962-66 Amimoniumo nitrate, ammonium sultate, sod(i umn nitrate, and1( urea xxere compared at N rates of 40, 80, and 120 pounds per acre. There xxas also a 160- and a :320-pound N rate xxith ammonnium nitrate. Phosphorus andl potassitum xwere applied in a single appli- 6 ALABAMA AGRICULTURAL EXPERIMENT STATION Yield, lb/acre 4,000 P No 12,000 Q PK 0,000 0D 8, 000 Wth 2,0 6,000 4,000 o I~ ______ ______j11______ 958 1959 1960 1961 Yeaor FIG. 2. Yields of .ahnsongrass plus Caley peas with and phorus and potassium, 1958-61, ore illustrated here. without added phos- cation b)ef ore (gr( wth start('d at the per acre i ate( of 89 poun ds of 1' and 165 potnids of K. I i \ e- c ar ax era(Ie N ieldls shoxx an in crease from each in cr( ment of N applied froni annioiiiui nitrate. l'ilrlre :3. Y iclds wee ioxx as a result of droiightx conditins in 1962 anid 1963; ho~ cvcx r, there xxas at respon se to each rate of N in ex enti x ear of the cxperimelit. FERTILIZER FOR JOHNSONGRASS Yield, lb/acr e 10,00 8,000 - - - 6,00 4,000 2,000 0 4 0 80 120 160 20 240 280 320 Nitrogen applied each year, lb./ocre FIG. 3. Effect of nitrogen rote, from ammonium 1962-66, is illustrated here. nitrate, on johnsongross yields, Yield, I b/acre 6,000 ® Ammonium sulfate jjAmmonium © Sdu irt nitrate Urea 4,000 2,000 0 40 80 120 Nitrogen applied each year, lb/acre FIG. 4. Average yields of johnsongrass from four sources of nitrogen, are illustrated here. 1962-66, 8 ALABAMA AGRICULTURAL EXPERIMENT STATION Yield1s XXere simiilar w~ithi alHlmoIlilII nitrte anid Sod(ium1 nitrate, 1'iglire 4f. The Nild resp)(nses from ali ( nloiln sllate andl urea were'ft similar. AmmonI~fiumi nitrate aii sodliumi nitrate resuiltedl ini higher xieldls than either alniInh0ii um sullfate or urea. The lo\\er Pct. of applied N recovered in gross 60 Li Ammonium Urea sulfate El f Ammonium Sadium nitrate nitrate 50 40 30 20 I0 40 80 120 Nitrogen applied each year, lb./acre FIG. 5. Percentage of appli~d nitrogen from four sources recovered gross, 1962-66, is illustrated here. in johnson- FERTILIZER FOR JOHNSONGRASS of loss of ic'd fIon i these all-ammoni1 a sources of N wxas prolhabl aililnonia as ias. tbe result \inillonia prodllciilg( N souirces app)lied to thle suirface of calcar('ois soil, such as Suiimter clay-, max- be suibject to losses of aimmon1(11ia (,as. Whe1n( the soil surfa~ice' is mol(ist chemyical1 reacltion s iiax cccii that xwill relase somte of the ailiia ito th atmiospliere. l loixxcx (0' ifthe N iiaterial is tuirinedl into the soil or rains imh)\e tihe fe rtiizer l)(lowv tihe soil surface, thei the ammoi ia releasedl is n ot lost since it is held( by the soil particles. Laboratorx results conlfirmned the la -c loss of ammonia (ras frem tlu se allauioiiia souces of N. Ain(th er mleasure (If tihe efhiciencx of N aj)1)~ications is tihe _ aimouti of(Iapplied 'N recIx coed in the formxe. Axverage N recox erv rim~ed fromi low of 22 per cent wxithl ailllliliiun sulfate to at hligl (If' per cent xxithI sodium nitrate, LFi(iuie 5. This nitrog.eni 60 recox erx (fraphl Shoxx ti sai I trenids as the x eclds iin Fiiyriie 4t. a The 'Nconitenlt of thle fo~raiye increased xxtl rate of applied 'N i frlm all so urces, iguire 6. The ax eral r 'Ncointents of joliis(Iii 1arass groxwi wxith the 16(0- and 320-pouiid r ates (If N wx're 1.88 p~er c int aind ).13 per cenit, respecctix (,IN-. These x allies corresponid( to crude protein couiteiits ofI 11.8 per cent andI 1:3.3 per cent. The stand of johiisong~rass xx excellen t xxheni the experiiieit as xas hewpn in 1958. \fter 5 x ca s there xx as atserioIus stand~ deple- Ncnet ® Ammorium sulfate a Ammonium Sodium nitrate per cent 18 1.7 Urea nitrate 151 0 40 80 120 Nitrogen applied each year, lb/acre FIG. 6. Effect of rate and source of n~itrogenl on total nitrogen in johnsongrass, 1962-66, is illustrated here. 10 ALABAMA AGRICULTURAL EXPERIMENT STATION Pct. stand in 1963 100 90 80 70 60 50 40 30 20 10L I____ 08 40 BC 10 __ ____ __ 0 60 320 Nitrogen applied each year, lb./acre FIG. 7. Effect of nitrogen on johnsongross stands after application for 5 years, 1959-63, is illustrated here. toll xxi ten'l lowVrat('s of N had hecii applied, Fi gure 7.Th ere xx(re not cliff ereites anion", soln-ces of N ill their iefect on1 standc. Wh lere thet stanid \Xu poor, dropseed (Sjmrobolus /)oiretir (Roloei. Sellt. 1 IL itelhe. ) andc (oxtail ( S('1(iia Itt('s(('t1 ( Wei(1gel ) Huli1 . ) were thet Prex aler t xx eds. FTic poorer the johi sot grass standl the reater Ia xx tihe xxeed1 popuilation. as Nitrates in Johnsongross malill(11 her grasses wrill accutto late of ) tntder cer'taint et itan tettl conditiolts, .Suchl as5 ctottlittWlett (a large a tilut t of nlittate is /)rcet itt the soil. F'ora"'( eotttaitlit mottrC thtatn .2 p~er cu(lit NO, - bhs been eottlsilet'ed p)otentlliallyj toxie to runan~l~l~ t niols. flocer er, it th 10/01so gtyls's alongitra jte ttitro('tl (' (-N hx Oil 11a aid Oil(thir Ilunliit ( mtaiiiii N'ihti. \\x . Agr. Epp. Sta. Bull. 241. FERTILIZER FOR JOHNSONGRASS (deIfin itt' toxic lc i ci .xince' it L (riets wcith is not oss)O5iIbl to "ilc a SuchI fac'tors' (IS cond~itionI of iltc aonoimal (111d amiounIt of forage' con- G eneiraliy n itr ates wcree (consideraly b elo«x the lex el conisid('red potel tiallx toxic c\ eli \\ 10 the :320-pouiid irate of N xxas applied. lTh hii gh(st conicenitrationi iiieasi ed was 0.17 per cent Nas nitrate in the Jnix 1963 hlar\ est wxhere :320 polndts of N wxas appilied. NIost hiarx (st s conin i(( none or oinix a trace of n itirates regardless of rate or source of N. Wheni nitrates xx eve found~ inl the grass, the con)itentI increased slightlixxxith inlcreasingr rate of b ut xxas similard foi all sourices of N. RATES OF PHOSPHORUS AND POTASSIUM, 1963-67 Therc xxas at smallf increI as i x id f roin 22 pounds of 1) per acre but nowe from a iglher rate. Limgi ii( . There xwas also~ little or no response to applihd K. \lppareiitlx thie largest response xxas from the N. Both staind and gioxth xx (rc poor xxhere no fertilizer xxas adlded. Yield, lb/acre 18,00 6,000 4,000 0-0-0 200-0-65 200-2-65 20044- '- 0-44.0 200.44-42 200-4483 N-P-K fertilizer odded, lb/acre FIG. 8. Effect of nitrogen, phosphorus, and potassium fertilizer on yield of johnsongross, 1963-67, is illustrated here. 12 ALABAMA AGRICULTURAL EXPERIMENT STATION RATES OF NITROGEN, PHOSPHORUS, POTASSIUM, AND MAGNESIUM, 1965-70 Fertilizer treatments and yields are given in the table. Yields are grouped into two 3-year averages since rainfall differences resulted in much higher yields during 1965-67 than in 1968-70. YIELDS OF JOHNSONGRASS FROM THE RATES OF NITROGEN, PHOSPHORUS, POTASSIUM, AND MAGNESIUM EXPERIMENT, 1965-70 Average yields of oven-dried Element added, pounds/acre johnsongrass per acre N 0 50 50 50 50 100 100 100 100 200 200 200 200 200 200 200 200 200 200 200 1Applied P K Mg 1965-67 Lb. 4,700 7,200 7,900 6,900 6,800 9,200 9,500 7,800 9,200 10,000 11,000 11,500 11,400 11,800 11,800 11,800 11,300 12,900 11,600 12,500 1968-70 Lb. 3,100 4,300 4,500 4,300 4,500 5,500 5,800 5,500 5,700 5,600 6,500 7,100 6,600 7,200 5,600 7,600 7,400 7,600 7,100 7,300 1965-70 Lb. 3,900 5,800 6,200 5,600 5,700 7,400 7,700 6,700 7,500 7,800 8,800 9,300 9,000 9,500 8,700 9,700 9,400 10,300 9,400 9,900 0 25 100 0 25 0 25 25 0 25 50 0 25 100 0 25 0 0 25 25 0 25 50 0 25 100 0 25 0 0 25 25 0 25 50 0 25 100 0 25 200 0 0 100 0 50 100 0 25 100 25 25 200 25 25 100' 0 25 2001 0 in two equal applications. There was a response to each increase in rate of N. Nitrogen had a much greater effect on yield than did the other elements applied. As in the 1963-67 experiment, there was a small increase in yield from P. This increase became progressively larger toward the end of the experiment. Yield increases from K were both small and erratic. Evidently the soil K was sufficient to preclude a response to more than 25 pounds of K. It made little or no difference whether the K was applied in a single or a split application. Magnesium had no effect on yield. Weed infestation measurements made at the end of the 6-year experiment show that the higher the rate of N the lower the weed FERTILIZER FOR JOHNSONGRASS 13 Weed infestation, per cent 50 V- 40 I- Nitrogen rate, l b/acre 1965-70, FIG. 9. Effect of applied nitrogen on weed infestation after 6 years, is illustrated here. popu1 lation f1 iguire 9.. \pparentl \ N f ertilIizers prodIu ced densei stainds aid (1mor)V \i~orous (rrowtb of the john1songr~ass planits, SUMMARY AND CONCLUSIONS Contchtsions fro 0tH1(1tilt\ c \1 )(imHcnts ionidutttedIx ith johutso)l- grass on1 ealcav'otls Siti tter clay soil at the Black Belt Suihstatiot d1iu-iti 1958-70) are as foliox~ s: 1. There \\er crc ld in creases from each) incrtumint of' X up to 320 pound(s per acre, the highest rate itn any of the (xperimvenlts. 14 ALABAMA AGRICULTURAL EXPERIMENT STATION 2. Caley peas in rotation with johnsongrass increased total yield where less than about 200 pounds of N was added. 3. Yield responses to P and K were small; however, there was a loss of stand and a greater weed population where no P or K was added. 4. The higher the rate of N the better the johnsongrass stand and the lower the weed population. 5. Ammonium nitrate and sodium nitrate resulted in higher yields than either ammonium sulfate or urea. 6. The higher the N rate the higher was the N content of johnsongrass. 7. Most harvests of johnsongrass contained none or only a trace of N0 3-N regardless of rate of N applied. When nitrates were present in the grass, the higher the rate of N the higher were the nitrates. The highest level ever measured in a single harvest was 0.17 per cent NO 3-N. AGRICULTURAL EXPERIMENT STATION SYSTEM OF ALABAMA'S LAND-GRANT UNIVERSITY With an agricultural research unit in every major soil area, Auhurn University serves the needs of field crop, livestock, forestry, and hor- D T ( ticultural producers in each region in Alahama. Every citizen of the State has a stake in this research program, 0 J it m G. since any advantage from new and more economical ways of producing and handling farm products directly lbenefits the consuming v piublic. Research Unit Identification 1. 2. 3 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21 Tennessee Valley Substation, Belle Mina. Sand Mountain Substation, Crossville. North Alabama Horticulture Substation, Cuilman Upper Coastal Plain Substation, Winfield. Forestry Unit, Fayette Counry. Thorsby Foundation Seed Stocks Farm, Thorsby. Chilton Area Horticulture Substation, Clanton. Forestry Unit, Coasa Caunty. Piedmont Substation, Camp Hill. Plant Breeding Unit, Tallassee. Forestry Unit, Autauga County. Prattville Experiment Field, Prattville. Black Belt Substation, Marion Junction. Tuskegee Experiment Field, Tuskegee. Lower Coastal Plain Substation, Camden. Forestry Unit, Barbour County. Monroeville Experiment Field, Monroeville. Wiregrass Substation, Headland. Brewton Experiment Field, Brewton Ornamental Horticulture Field Station, Spring Hill. Gulf Coast Substation, Fairhope.