EVALUATION OF CORN AND SOYBEAN RESPONSE TO PHOSPHORUS AND POTASSIUM FERTILIZATION INGRID ARNS. B.S., Universidade Federal do Rio Grande do Sul, 2010

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1 EVALUATION OF CORN AND SOYBEAN RESPONSE TO PHOSPHORUS AND POTASSIUM FERTILIZATION y INGRID ARNS B.S., Universidde Federl do Rio Grnde do Sul, 2010 A THESIS sumitted in prtil fulfillment of the requirements for the degree MASTER OF SCIENCE Deprtment of Agronomy College of Agriculture KANSAS STATE UNIVERSITY Mnhttn, Knss 2013 Approved y: Mjor Professor Dorivr Ruiz Diz

2 Copyright INGRID ARNS 2013

3 Astrct Corn (Ze mys) response to fertiliztion nd plcement methods hs een studied extensively; however studies on soyen [Glycine mx (L.) Merr.] response to plcement hve een limited. Three studies were completed to evlute different spects of crop response. The ojective of the first study ws to evlute the effect of strter nd rodcst fertilizer ppliction on corn nd soyen, in typicl corn-soyen rottion in Knss. Tretments were unfertilized control, strter (N, P nd K), rodcst P nd K using mono mmonium phosphte (MAP) nd potssium chloride (KCl) nd the comintion of strter nd rodcst. Corn nd soyen yield generlly ws not ffected y strter nd rodcst tretments. Thus fertiliztion my e recommended only under specific conditions. The ojectives of the second study were (i) to evlute the effect of residul nd direct fertiliztion on soyens fter corn under cornsoyen rottion system, nd (ii) study the effect of fertilizer P nd K ppliction on soil test P (STP) nd soil test K (STK) chnges over time. Direct fertiliztion incresed soyen yield while residul fertilizer did not. Therefore mintennce rtes my e effective to improve soyen yield nd likely mintin STP nd STK levels. Appliction of P nd K fertilizer generted significnt increses in STP nd STK fter one yer of ppliction. The rte of P nd K fertilizer required to increse 1 mg kg -1 yr -1 ws etween kg h -1 for P nd etween kg h -1 for K, respectively. The ojective of the third study evlute oth corn nd soyen response to direct P fertiliztion including strter nd rodcst. The tretments were control, two strter fertilizers (with N-P nd N only), five P rtes (9.8, 19.6, 29.3, 39.1, 48.9 kg P h-1) nd one tretment with strter fertilizer in ddition to the rodcst fertilizer ppliction. Corn grin yield ws not significntly ffected y ny rodcst or strter tretments. Brodcst ppliction rtes significntly incresed soyen yield on low STP levels. Results of this study show tht lrge

4 corn or soyen yield response to strter nd rodcst P ppliction re likely with low STP levels.

5 Tle of Contents List of Figures... vii List of Tles... ix Acknowledgements... x Dediction... xi Chpter 1 - Introduction nd Thesis Orgniztion... 1 Phosphorus nd potssium fertiliztion on soyen nd corn... 1 Thesis Orgniztion... 3 References... 3 Chpter 2 - Corn nd soyen response to strter nd rodcst fertiliztion... 5 Astrct... 5 Introduction... 6 Mteril nd Methods... 8 Results nd Discussion Corn Soyen Conclusion References Figures nd Tles Chpter 3 - Evlution of soyen response to direct nd residul fertiliztion Astrct Introduction Mteril nd Methods Results nd Discussion Soil test vlues Crop response Conclusion References Figures nd Tles Chpter 4 - Corn nd soyen response to phosphorus fertiliztion nd plcement v

6 Astrct Introduction Mteril nd Methods Results nd Discussion Corn Soyen Conclusion References Figures nd Tles Chpter 5 - Generl Conclusions vi

7 List of Figures Figure 2.1. Plcement effects on corn erly growth t V6 growth stge () nd grin yield () cross loctions 1 nd 3, loctions 2 nd 4 nd cross ll loctions. Loctions 1 nd 3 were no-till, non-irrigted nd hd rodcst ure s N source; loctions 2 nd 4 were conventionl tillge, irrigted nd nhydrous mmoni ws used s N source. Different letters for ech r group indicte sttisticlly significnt differences t the P < Figure 2.2. Plcement effects on erly plnt P (), K (c) nd N (e) concentrtion nd P (), K (d) nd N (f) uptke in corn t the V6 growth stge cross loctions 1 nd 3, 2 nd 4 nd cross ll loctions. Loctions 1 nd 3 were no-till, non-irrigted nd hd rodcst ure s N source; loctions 2 nd 4 were conventionl tillge, irrigted nd nhydrous mmoni ws used s N source. Different letters for ech r group indicte sttisticlly significnt differences t the P < Figure 2.3. Plcement effects on er lef P (), K () nd N (c) concentrtion on corn t R2 growth stge cross loctions 1 nd 3, 2 nd 4 nd cross ll loctions. Loctions 1 nd 3 were no-till, non-irrigted nd hd rodcst ure s N source; loctions 2 nd 4 were conventionl tillge, irrigted nd nhydrous mmoni ws used s N source. Different letters for ech r group indicte sttisticlly significnt differences t the P < Figure 2.4. Plcement effects grin P () nd K( ) concentrtion nd P (c) nd K (d) removl on corn cross loctions 1 nd 3, 2 nd 4 nd cross ll loctions. Loctions 1 nd 3 were notill, non-irrigted nd hd rodcst ure s N source; loctions 2 nd 4 were conventionl tillge, irrigted nd nhydrous mmoni ws used s N source. Different letters for ech r group indicte sttisticlly significnt differences t the P < Figure 2.5. Plcement effects on soyen trifolite P (), K () nd N (c) concentrtion t R1 growth stge, nd on seed yield (d) cross loctions 1 nd 3, loctions 2 nd 4 nd cross ll loctions. Loctions 1 nd 3 were no-till nd non-irrigted; loctions 2 nd 4 were conventionl tillge nd irrigted. Different letters for ech r group indicte sttisticlly significnt differences t the P < igure 2.6. Plcement effects on soyen seed P () nd K () concentrtion, nd on P (c) nd K (d) seed removl cross loctions 1 nd 3, loctions 2 nd 4 nd cross ll loctions. Loctions 1 nd 3 were no-till nd non-irrigted; loctions 2 nd 4 were conventionl tillge vii

8 nd irrigted. Different letters for ech r group indicte sttisticlly significnt differences t the P < Figure 3.1. Soil test P (Mehlich-3) nd K (Ammonium cette) levels s ffected y fertilizer ppliction of 59 kg P h -1 (10 k P h -1 s strter nd 49 kg P h -1 s rodcst) nd 110 kg K h -1 (18 kg K h -1 s strter nd 92 kg K h -1 s rodcst) in 2012 fter one yer of fertilizer ppliction on non-fertilized plots from Figure 3.2. Rte of P nd K fertilizer required to increse 1 mg kg -1 yr -1 of P nd K in Ashlnd nd Topek. Soils were first smpled efore fertiliztion on Mrch 2011 nd were then smpled gin one yer fter fertilizer ppliction (Mrch 2012) Figure 3.3. Direct nd residul rodcst fertiliztion effects on soyen yield nd lef P concentrtion (R2 growth stte) for ech loction nd cross loctions in Direct fertiliztion consisted of 20 kg P h -1 nd 65 kg K h -1 nd residul of 49 kg P h -1 nd 93 kg K h -1. Soyen ws plnted over the corn residue plots trils from Ashlnd ws no-till nd non-irrigted nd Topek ws conventionl tillge nd irrigted. Different letters indicte sttisticlly significnt differences t the P < Figure 4.1. Men corn erly growth () nd uptke () t V6 growth stge, nd er lef P concentrtion (c), response to P fertiliztion cross loctions. Models were fit cross the rodcst P rtes only Figure 4.2. Men soyen trifolite P concentrtion () nd grin yield () response to P fertiliztion cross loctions. Models were fit cross the rodcst P rtes only viii

9 List of Tles Tle 2.1 Loction description, soil clssifiction, preliminry soil nlysis, hyrids, vrieties, tillge, nd plnting dte for 2011 nd Tle 2.2. Significnce of F vlues for tretment effects on corn erly growth, N, P nd K concentrtion nd uptke t the V6 growth stge, er lef N, P nd K concentrtion t the R2 growth stge, nd grin yield for ech loction nd cross loctions Tle 2.3. Significnce of F vlues for tretment effects on corn yield, nd on N, P nd K grin concentrtion nd removl Tle 2.4. Corn yield nd erly growth t V6 growth stge s ffected y strter nd rodcst fertiliztions Tle 2.5. Plcement effects on erly plnt N, P nd K concentrtion nd uptke in corn t V6 growth stge nd on er lef N, P nd K concentrtion t R2 growth stge, nd N, P nd K grin concentrtion nd removl Tle 2.6. Significnce of F vlues for tretment effects on N, P nd K trifolite concentrtion t R1 growth stge, on seed yield nd on N, P nd K grin concentrtion nd removl Tle 2.7. Soyen lef P nd K concentrtion t R1 growth stge, seed yield, nd seed P nd K concentrtion nd removl s ffected y strter nd rodcst fertiliztions Tle 3.1. Loction description, soil clssifiction, soil nlysis, vrieties, tillge, nd plnting dte for soyen Tle 3.2. Description of soyen P nd K rodcst rtes pplied on yer 1 s residul fertiliztion from corn nd the following yer 2 s direct fertiliztion pplied on soyen. 52 Tle 4.1. Loction description, soil clssifiction, preliminry soil nlysis, hyrids, vrieties, tillge, nd plnting dte Tle 4.2. Phosphorus fertiliztion nd plcement effects on corn erly growth, erly P concentrtion nd uptke in corn t the V6 -V7 growth stge, P concentrtion in the er lef t the R2 growth stge nd grin yield Tle 4.3. Phosphorus fertiliztion nd plcement effects on soyen lef (trifolite) P concentrtion t the R1 growth stge nd on soyen yield ix

10 Acknowledgements I m deeply grteful to Dr. Dorivr Ruiz Diz for his commitment s my mjor dvisor, whose expertise, understnding, nd ptience, dded considerly to my grdute experience. I would like to thnk the other memers of my committee, Drs. Dvid Mengel nd Aln Schlegel for their ssistnce nd feedck during my Mster progrm. Apprecition lso goes to Knss Stte University for the opportunity nd to the Deprtment of Agronomy fculty nd stff for supporting my reserch. I must lso cknowledge the grdute nd undergrdute students prt of our soil fertility progrm for their help with the field nd l work: Dr. Nthn Mueller, Evn King, Aron Widmr, Pulo de Oliveir Neto nd Sntigo Pc. Lst ut not the lest I would lso like to thnk my prents Ulfried nd Adrine, my rothers Rodolfo nd Arthur, my prtner Alvro nd my der friends for supporting me in this journey. x

11 Dediction This thesis is dedicted to Rolf Derpsh, wonderfully rillint mn who hs given the most contriution to more sustinle griculture with the development of No-tillge technology in Brzil, Ltin Americ nd cross the world. Rolf hs een lwys fighter nd leder, ut more thn tht he is such loving nd giving mn. Rolf encourged nd gve me the opportunity to rech my drems nd ecuse of him I m chieving one of them, which is my mster degree in the USA. I thnk Rolf for chnging my life nd for ringing me so much hppiness. xi

12 Chpter 1 - Introduction nd Thesis Orgniztion Phosphorus nd potssium fertiliztion on soyen nd corn Phosphorus nd potssium fertilizer demnd nd price incresed to gret extent during the pst two decdes (USDA, 2012). Therefore more efficient fertilizer mngement strtegies re necessry, not only to increse frmer profitility ut lso to reduce wter contmintion prolems. In Knss the medin vlues for P is 18 ppm Bry P-1 equivlent nd pproximtely 55% is the reltive frequency of soils found to e elow criticl level of 20 ppm (Fixen et l., 2010). The medin P level for Knss soils hs declined compred to 2005, when the medin ws 21 ppm. This chnge is proly due to the cumultive effects of crop removl exceeding P use (Fixen, 2006; Fixen et l., 2010). Corn nd soyen yield nd producer s profit usully re incresed y ppliction of P fertilizer to soils in the very low or low ctegories (Mllrino, 1991). Yield increses from fertilizer follow curve of diminishing returns (Troeh nd Thompson, 2005). Smll pplictions of needed fertilizer result in the gretest return per unit of nutrient pplied, wheres dditionl mounts of fertilizer hve smller increse in yield. Eventully point is reched where the lst increment of fertilizer dded rely increses yield enough to py the cost of ppliction. The criticl vlue for phosphorus used in Knss is 20 ppm for oth corn nd soyen (Leikm et l., 2003). Soil test vlues ove this level hve shown tht P fertiliztion is rrely profitle for either of these crops (Mllrino, 1991; We et l., 1992). The effect of fertiliztion nd plcement methods on corn nd soyen re usully oserved in no till systems. Under this condition the surfce residue cn result in cooler nd wetter soils compred to soils under conventionl tillge systems (Fortin, 1993). Therefore in no-till systems strter fertilizer ppliction cn hve positive effect on erly growth nd grin yield, incresing the nutrient 1

13 concentrtion nd vilility in the root zone when low soil temperture slow root growth nd nutrient diffusion (Borkert nd Brer, 1985). Overll, yield increses due to strter ppliction re most frequently found on low testing soils, poorly drined soils, lte plnted crops, hyrids of long mturity groups, nd conservtions tillge systems (Bundy nd Andrski, 2001; Rndll nd Hoeft, 1988). Brodcst phosphorus fertiliztion frequently increses corn nd soyen yield when soils hs low to very low STP nd rrely on soils with high STP (Bordoli nd Mllrino, 1998; Borges Mllrino, 2000). Dodd nd Mllrino (2005) showed in long term study tht corn nd soyen responded to nnul P fertiliztion 50 to 70% of the time when soil test level ws equl or less thn 20 ppm nd did not responded to higher test P. Similrly Mllrino (1991) indicted tht yields of corn nd soyen re not significntly ffected y either P or K fertiliztion in high P nd K testing soils. Therefore profitility of these crops cn e significntly reduced y ppliction of P nd K fertilizers to increse soil test vlues ove the medium rnge. Generlly, the literture shows consistent erly growth nd nutrient uptke responses to fertilizer on high- testing soil sites ut inconsistent yield responses (Bermudez nd A.P. Mllrino, 2002; Mllrino et l., 1999; Rndll nd Hoeft, 1988) Since most of the soils in Knss hve medium to high STP nd high STK levels, it is importnt to evlute how crops respond to fertilizers plcement nd rtes under these soil test levels. Fertilizer ppliction s strter or rodcst, oth hs een evluted for corn. However, studies on soyen response nd plcement re limited in Knss. The following three chpters evlute the corn nd soyen responses to strter nd rodcst P nd K. 2

14 Thesis Orgniztion This thesis is divided into five chpters. Following this introductory chpter, there re three chpters, ech of them consisting of one reserch project. Titles of chpter 2, 3 nd 4 re: Corn nd soyen response to strter nd rodcst fertiliztion, Evlution of soyen response to direct nd residul fertiliztion, nd Corn nd soyen response to phosphorus fertiliztion nd plcement. The fifth chpter is the overll conclusion. References Bermudez M., nd A.P. Mllrino Yield nd erly growth responses to strter fertilizer in no-till corn ssessed with precision griculture technologies. Agron J. 94: Dodd J.R., nd A.P. Mllrino Soil-test phosphorus nd crop grin yield responses to long-term phosphorus fertiliztion for corn-soyen rottions. Soil Sci. Soc. Am. J.69: Fixen P.E Soil Test Levels in North Americ. Better Crop With Plnt Food. 90(1) 4-7. Fixen, P.E., T.W. Bruulsem, T.L. Jensen, R.M. Mikkelsen, S.T. Murrel, nd S.B. Phillips et l The fertility of North Americn soils. Better Crop With Plnt Food. 94(4): 6-8. Mllrino A.P., J.M. Bordoli, nd R. Borges Phosphorus nd potssium plcement effects on erly growth nd nutrient uptke of no-till corn nd reltionships with grin yield. Agron. J. 91: Mllrino A.P., J.R. We, nd A.M. Blckmer Corn nd Soyen yields during 11 yers of phosphorus nd potssium fertiliztion on high-testing soil. J. Prod. Agr. 4:

15 Rndll G.W., nd R.G. Hoeft Plcement methods for improved efficiency of P nd K fertilizers: review. J. Prod. Agr. 1: Troeh F.R., nd L.M. Thompson Soils nd Soil Fertility. 6th ed. Blckwell. Ames, IA. USDA- Economic Reserch Service Pulished estimtes dt se (PEDB). Aville t (verified 25 Fe. 2013). USDA-NASS, Wshington, DC. 4

16 Chpter 2 - Corn nd soyen response to strter nd rodcst fertiliztion Astrct Corn (Ze mys) response to fertiliztion nd plcement methods hs een studied extensively; however studies on soyen [Glycine mx (L.) Merr.] response hve een limited. The ojective of this study ws to evlute the effect of strter nd rodcst fertilizer ppliction on corn nd soyen, in typicl corn-soyen rottion in Knss. Erly growth, nutrient concentrtion, uptke nd yield, were evluted t four loctions for corn, nd four loctions for soyen during 2011 nd Tretments were unfertilized control, strter (N, P nd K), rodcst P nd K using mono mmonium phosphte (MAP) nd potssium chloride (KCl) nd the comintion of strter nd rodcst. Soil smples nd plnt tissues were collected nd nlyzed for N, P nd K concentrtion. Corn erly growth ws mesured t the V6-V7 growth stge nd yield determined t the end of the seson. Corn erly growth, P nd K concentrtion nd uptke in young corn plnts were significntly incresed cross loctions. Grin P or K removl ws not ffected y fertiliztion in corn. Individul loctions showed no significnt effect of strter nd rodcst tretments on corn yield. However, cross loctions 1 nd 3 yield ws incresed with the ddition of strter fertilizer. Phosphorus concentrtion in soyen lef ws incresed y rodcst ppliction. Soyen yield ws not ffected with strter or rodcst fertilizer ppliction; however seed P removl ws incresed with rodcst ppliction. Corn nd soyen yield ws generlly not ffected y strter nd rodcst tretments in our study. 5

17 Introduction Fertilizer mngement nd ppliction method cn sustntilly ffect yield response nd producer s profitility. Strter fertilizer is common prctice to increse crop growth, stnd uniformity nd enhnce yield potentil. Some studies evluted the effects of plcement nd fertiliztion of P nd K on different crops nd hve shown tht strter fertilizer often increse corn yield compred to control tretment with no fertiliztion (Bundy et l., 2005; Rndll nd Hoeft, 1988). This response cn e frequent in soils with P nd/or K deficiency. In Knss ccording to Fixen et l. 2010, the medin vlues for P re 18 ppm Bry P-1 equivlent nd 274 ppm for exchngele K (Crson, 1980). Also pproximtely 55% nd 13% is the reltive frequency of soils found to e elow criticl levels for P nd K respectively (Fixen et l., 2010). The criticl vlue for phosphorus used in Knss is 20 ppm for oth corn nd soyen (Leikm et l., 2003). Below this level significnt proility of yield response cn e expected when pplying P fertilizer. Soils high in nutrient level do not lwys supply enough nutrients to the plnt during the erly prt of the growing seson given tht certin conditions cn limit the nutrient vilility (Ketcheson, 1968). Low soil temperture for exmple, cn reduce root growth (Ching nd Brer, 1979; Hvlin, 2005) nd nutrient uptke y plnt (Mcky nd Brer, 1985). Under these conditions, strter fertilizer ppliction cn hve positive effect on erly growth nd grin yield, incresing the nutrient concentrtion nd vilility in the root zone when low soil temperture slow root growth nd nutrient diffusion (Borkert nd Brer, 1985). Overll, yield increses due to strter ppliction re most frequently found on low testing soils, poorly drined soils, lte plnted crops, hyrids of long mturity groups, nd conservtions tillge systems (Bundy nd Andrski, 2001; Rndll nd Hoeft, 1988). 6

18 Some studies evluting yield response to strter fertiliztion hve shown inconsistent results due to mny fctors (Kiser et l., 2005). Rehm nd Lm (2009) found tht strter fertilizer N, P or N, P, nd K incresed corn erly growth under no tillge conditions nd where P nd K levels were optimum to high, ut this increse did not necessrily resulted in incresed grin yields. Likewise, other studies found significnt corn erly growth response to strter, however yield responses of no-till corn to strter re more likely when soil test P is elow optimum nd/or preplnt or sidedress N rtes re deficient (Bermudez nd Mllrino, 2002; Kiser et l., 2005). These studies indicte tht corn erly growth response to strter fertilizer is n unrelile indictor of grin yield. Vetsch nd Rndll (2002) however showed tht strter fertilizer incresed corn yields on high P nd K soils in continuous corn nd corn-soyen rottion nd they suggest tht strter fertilizer should e considered to optimize corn production cross ll tillge systems. Similrly, Touchton (1988) indictes tht strter N nd P frequently improved erly growth nd incresed corn grin yield under soils high in P. Another study lso showed corn yield response to strter fertilizer in no-till ut not in conventionl tillge system on high-testing P nd K silt lom soil (Wolkowski, 2000). According to Eckert nd Johnson (1985) nd Howrd nd Tyler (1987) nding fertilizer is preferle method for P pplictions to no-tillge corn. They concluded tht strter under conservtion systems hs generlly higher yield, nd therefore incresed fertilizer efficiency when compred with surfce rodcsting t low to moderte soil test P levels. Conversely, Howrd nd Essington (2002) found tht rodcst P rtes incresed no till corn yields t low STP nd tht yield responses to nding N-P were inconsistent over 11 yers. Kiser et l. (2005) on the other hnd showed tht strter P fertiliztion lone produced corn yield similr to lrge P rodcst rtes on soils with STP in the responsive rnge. 7

19 Mllrino (1991) nd Rndll et l. (1997) showed tht yields of corn nd soyen were not significntly ffected y either P or K rodcst fertiliztion in high P nd K testing soils. Likewise, nd ppliction of P or K show no yield enefit in soyen when soil tests re in the optimum or high rnges (Buh et l., 2000; Rehm nd Lm, 2010). Soyen yield response to P fertilizer ppliction is normlly found when soil test P (Mehlich-3) is elow 22 mg kg-1 nd similr to corn, not relted to erly growth (Mllrino nd Borges, 1997; Mllrino et l., 2009). In low P soils, soyen yield nd P uptke re incresed with P pplied in nd ner the seed (Rehm, 1988; Bullen et l., 1983). Hm (1973) showed tht rodcst N, P, nd strter N, P nd K significntly incresed soyen yields over the control when soils were low on P, however there ws no difference etween the plcement methods. Moreover, when soils were high on P nd K, no fertilizer tretment incresed soyen yield. Differently, Mllrino nd Borges (1997) found tht potssium fertiliztion incresed soyen yield under no-till when soil test K ws optimum to high. Fertilizer ppliction s strter, rodcst, nd the comintion of oth hs een evluted with emphsis on corn. However, studies on soyen response to plcement under different tillge systems re limited. The ojective of this study ws to evlute the effect of strter nd rodcst fertilizer pplictions on corn nd soyen in typicl corn-soyen rottion. Mteril nd Methods Four corn nd four soyen loctions were estlished in 2011 nd Fields with history of corn-soyen rottion were selected to represent common system in the region of study. Description of ech loction is presented in Tle 2.1. The experimentl design consisted of fctoril rrngement in rndomized complete lock design with four tretments nd four 8

20 replictions. The plot size ws 15 m long, 4-6 rows width with row spcing of 76 cm for oth crops. Strter fertilizer ws mixture of commercil formul (N-P-K) [ (N-P 2 O 5 - K 2 O)] nd ure mmonium nitrte (UAN) 28% N for totl ppliction of 17 kg h -1 of N nd 10.5 kg h -1 of P (24 kg h -1 P 2 O 5 ) nd 20 kg h -1 of K (24 kg h -1 of K 2 O). Brodcst fertilizer ws comintion of mono mmonium phosphte (MAP) [ (N-P-K)] [ (N-P 2 O 5 - K 2 O)] nd KCl [ (N-P-K)] [ (N-P 2 O 5 -K 2 O)] for totl ppliction rte of 49 kg h -1 of P (112 kg h -1 P 2 O 5 ) nd 93 kg h -1 of K (112 kg h -1 K 2 O). The rodcst ppliction rtes cn e considered commonly used rtes y producers efore corn in corn-soyen rottion nd intended for oth crops in the rottion (Leikm et l., 2003). Brodcst fertilizer ws pplied 1-4 weeks efore plnting t ll loctions. Brodcst fertilizer ws incorported t the loctions under conventionl tillge (loctions 2 nd 4 for oth corn nd soyen) efore plnting nd nonincorported t the no-till loctions (1 nd 3). Nitrogen fertilizer for corn ws pplied in spring one month prior to plnting injecting nhydrous mmonium t 168 kg N h -1 for loctions 2 nd 4. At loctions 1 nd 3, N ppliction rte ws 180 kg N h -1 pplied s side-dress t V5 corn growth stge (Aendroth et l., 2011) using ure. Loctions 2 nd 4 were irrigted for oth corn nd soyen, with center pivot sprinkler irrigtion systems nd irrigtion ws pplied s needed during the growing seson. Soil smples were collected from ech smll plot efore fertilizer ppliction. Ech smple ws composite of cores collected from the 0-15 cm depth. Smples were nlyzed for P y the Mehlich-3 method (Frnk et l., 1998) nd K with the mmonium cette method (Wrncke nd Brown, 1998). Soil ph ws mesured using 1:1 soil:wter rtio (Wtson nd Brown, 1998), nd soil orgnic mtter (OM) ws determined y Wlkley Blck method (Coms nd Nthn, 1998). 9

21 Plnt popultion ws mesured in 7.6-m section of two centrl rows of ech plot, for oth crops. Corn erly growth, nutrient content nd nutrient uptke ws evluted. Aoveground prts of 10 corn plnts were collected from ech loction t V6-V7 growth stge (Aendroth et l., 2011). Corn er leves were collected t the R1 growth stge nd soyen lef smples consisting of the most recently developed fully expnded trifolite lef (petiole excluded) etween erly loom (R1) nd full loom (R2) stges (Pedersen, 2009). Both corn nd soyen lef smples were nlyzed for N, P nd K. Plnt smples were dried t 60 o C in forced-ir oven, weighted (only for corn), nd ground to pss 2-mm screen. Ground smples were digested using sulfuric cid nd hydrogen peroxide in Digesdhl Anlysis System (Hch Co., 1991). Nitrogen nd P were mesured y colorimetry nd K ws mesured y flme photometry (Murphy nd Riley, 1962). Corn N, P nd K uptke ws clculted using nutrient concentrtions nd oven-dried weights. After corn nd soyen reched physiologicl mturity, yield ws determined y hrvesting the center two rows of ech plot. Hrvested ws completed with smll plot comine t ll loctions, except corn loctions 1 nd 3, where corn ers were hndhrvested. Grin yield ws djusted to moisture content of 155g kg -1 for corn nd 130g kg -1 for soyen. Sttisticl nlysis ws completed using the generlized liner mixed model (GLIMMIX) procedure of SAS (SAS., 2006) ssuming lock nd loctions s rndom fctors in the model. When significnt, plnt popultion ws used s covrite in the nlysis. Sttisticl nlysis ws completed y loction nd cross loctions. In ddition, nlysis ws completed y groups of loction ecuse of different mngement prctices nd contrsting yield levels. Corn loctions 1 nd 3 were no-till, non-irrigted nd hd sidedress ure s N source t V5. Differently loctions 2 nd 4 were conventionl tillge, irrigted nd hd pre-plnt nhydrous mmonium s N source. Soyen loctions 1 nd 3 were no-till nd non-irrigted wheres loctions 2 nd 4 10

22 were conventionl tillge nd irrigted. Sttisticl significnce ws determined t the P 0.10 level. Results nd Discussion Corn Corn erly growth ws incresed with fertiliztion t loctions 1, 2 nd 4 (Tles 2.2 nd 2.4). Although rodcst P-K rte ws lmost 10 fold the strter rte, iomss results shows the sme response etween strter nd rodcst pplied lone t ll loctions nd cross loctions. This suggests no dvntge of plcement for corn erly growth. This result grees with those of Mllrino et l. (2011) who found tht incresed erly growth with strter fertilizer ws similr to those of rodcst pplictions t higher rtes. At loction 1, only the comintion of strter nd rodcst incresed iomss over the control (Tle 2.4); with similr results cross loctions 1 nd 3 (Figure 2.1). At loction 2, rodcst nd strter lone significntly incresed erly growth over the control; however no dditionl increse in erly growth with the comined rodcst nd strter ppliction. At loction 4, cross loctions 2 nd 4 nd cross ll loctions, strter nd rodcst lone incresed significntly iomss over the control (Figure 2.1). Furthermore, there ws n dded ffect when they were pplied in comintion showing n increse on iomss over the strter or rodcst lone. This result differs from those of Kiser nd Mllrino (2005) where they found tht the comintion of oth plcements didn t contriute to dditionl increse in erly growth over either plcement lone. Fertiliztion ffected P concentrtion of young corn plnts t three loctions (1, 2, nd 4) (Tle 2.2). At loction 1 the comintion of strter nd rodcst incresed P concentrtion over strter nd rodcst lone ut not when compred to the control (Tle 2.5). At loction 2, 11

23 only tretments with rodcst significntly incresed P concentrtion. Strter lone decresed P concentrtion over the control t loction 4, however when pplied fter rodcst there ws no tretment effect. Across loctions 1 nd 3, fertiliztion hd no significnt effect in erly plnt P concentrtion (Figure 2.2). Across loctions 2 nd 4 nd cross ll loctions there ws n increse in P concentrtion when rodcst with strter ws pplied. However, strter lone showed decresed P concentrtion over other tretments (Figure 2.2). With the incresed erly growth resulted from strter fertilizer lone, possile nutrient dilution effect my explin the generlly lower P concentrtion with the strter lone tretment. The dilution effect ws found in previous studies (Plenet nd Lemire, 1999; Zidi et l., 2007). Brodcst showed no difference in P concentrtion compred to the unfertilized control (Tle 2.5 nd Figure 2.2). However, the comintion of strter nd rodcst show n incresed P concentrtion, which suggest tht higher P fertilizer rte my help to compenste the dilution effect. Erly P uptke ws incresed t three loctions y fertiliztion (Tle 2.2 nd 2.5), including the loction where strter decresed P concentrtion (loction 4). Brodcst ws sttisticlly different nd hd higher uptke thn strter only t loction 2 (Tle 2.5). At loction 1, only the comintion of strter nd rodcst incresed P uptke over the control. Similr results were found when nlyzing cross loctions 1 nd 3 (Figure 2.2). At loctions 2 nd 4, P uptke ws incresed significntly y oth strter nd rodcst. Nevertheless the comintion of oth plcements incresed P uptke more thn strter or rodcst lone (Tle 2.5). The result ws similr when nlyzing cross loctions 2 nd 4 nd cross ll loctions. Therey erly plnt P uptke seems to reflect fertiliztion effects on erly growth more closely thn plnt P concentrtion. These results gree with those of Kiser et l. (2005) who found significnt increse in erly growth nd inconsistent or lower plnt P concentrtion with fertilizer 12

24 ppliction. Brodcst incresed erly K concentrtion t loctions 2 nd 4, wheres strter hd no effect on K concentrtion t ny loction. The comintion of strter nd rodcst incresed K concentrtion t three loctions (1, 2 nd 4). Anlysis cross loctions 1 nd 3, show incresed erly K concentrtion with ll fertiliztion tretments. Wheres cross loctions 2 nd 4 nd cross ll loctions only tretments with rodcst fertiliztion incresed K concentrtion (Figure 2.2c). This grees with previous studies showing tht rodcst K frequently incresed erly plnt K concentrtion in corn (Clover nd Mllrino, 2012). Strter nd rodcst lone enhnced K uptke t loctions 2 nd 4 (Tle 2.5). At loction 1 nd cross loctions 1 nd 3, only the comintion of strter nd rodcst incresed K uptke. Across loctions 2 nd 4 nd cross ll loctions strter nd rodcst lone incresed K uptke over the control however the comintion of oth plcements hd sttisticlly higher K uptke compre to other tretments (Figure 2.2d). Erly plnt N concentrtion ws inconsistent etween loctions. Strter lone or in comintion with rodcst incresed N concentrtion only t loction 1 (Tle 2.5). Fertilizer tretments decresed N concentrtion t loction 4, similr to erly P concentrtion t this loction. Nevertheless nlysis cross loctions 1 nd 3, 2 nd 4, nd ll loctions show no effect of ny fertilizer tretment on erly N concentrtion (Figure 2.2e). According to Buh et l. (1999) strter N-P-K fertilizer increses plnt K concentrtion much more frequent thn plnt N nd P concentrtion, this explin the lck of response of erly N nd P concentrtion to strter ppliction in this study. Strter lone or in comintion with rodcst incresed plnt N uptke t three loctions (loctions 1, 2 nd 4) (Tle 2.5). Across loctions 1 nd 3, only the comintion of strter nd rodcst incresed N uptke over the control (Figure 2.2f). Strter nd rodcst lone incresed N uptke over the control cross loctions 2 nd 4 nd ll 13

25 loctions, however the comintion of oth hd significnt higher uptke compre to the other tretments. Fertiliztion tretments incresed er lef P concentrtion t the R2 growth stge only t loction 1 (Tle 2.2 nd 2.5). Across loctions 1 nd 3 however, ll fertilizer tretments incresed P concentrtion over the control (Figure 2.3). Brodcst ppliction incresed er lef P cross loctions 2 nd 4 (Figure 2.3). Across ll loctions rodcst lone nd with strter significntly incresed er lef P. These results re similr to those of Howrd nd Mullen (1991) who found incresed er lef P concentrtion with high rodcst P pplied prior plnting. This suggest tht higher rtes pplied with rodcst fertiliztion ffect plnt P concentrtion longer in the seson compre to strter ppliction. Potssium concentrtion in the er lef ws not incresed y ny tretment t ny loction or cross loctions (Tle 2.2, Figure 2.3). Other studies found similr results with no response to of lef K concentrtion to strter (Mengel et l. 1988). Conversely, in some other work the rodcst ppliction hs shown tht lef K concentrtion is consistently incresed with rodcst K ppliction (Rndll et l. 1997; Clover nd Mllrino 2012). Strter or rodcst lone decresed er lef N concentrtion compre to the control t loction 2, wheres the comintion of oth plcement showed no chnge on er lef N concentrtion (Tle 2.2). At loction 4, strter fter rodcst decresed N concentrtion over the control. Anlysis cross loctions 2 nd 4 suggest tht rodcst tretments decrese N concentrtion in the er lef (Figure 2.3c). These results re similr to N concentrtion t erly growth V6-V7 stge. Anlysis cross loctions shows similr results for er lef N concentrtion with no significnt differences etween tretments. This result grees with those of Touchton (1988) tht shows N concentrtions in the er lef were not ffected y ny strter N-P tretment. 14

26 Yield level t drylnd loctions (1 nd 3) ws low compred to the irrigted loctions (2 nd 4) during 2011 nd None of the individul loctions showed significnt effect of strter or rodcst tretments (Tle 2.3 nd 2.4). Nevertheless, nlysis cross loctions 1 nd 3 showed significnt yield response to strter (Figure 2.1). Soil test P t these loctions ws t the optimum level or ove, nd these results re in greement with those of Buh nd Polito (1999) nd Bundy nd Andrski (2001). They reported positive grin yield response to the ddition of fertilizers pplied s strter under no tillge conditions on soils medium to high in P nd K. Although strter lone incresed yield, when in comintion with rodcst there ws no yield response. This lck of response could e explined when we look into grin moisture nlysis cross loctions (dt not shown). Grin moisture from strter tretment ws 110 g kg-1, sme s the control. Brodcst in comintion with strter hd significnt higher moisture of 138 g kg-1. Thus rodcst my hve delyed plnt development compre to plnts with strter tretment, nd therefore plnts were ffected y the dry condition in different growth stges. Across loctions 2 nd 4 there ws no significnt effect on yield with fertilizer tretments. These results re similr to those of Bullock et l. (1993), who found no increse in grin yields with strter fertilizer under conventionl tillge nd medium to high soil test levels. Anlysis cross ll loctions lso showed no significnt yield difference etween tretments. Tretments with rodcst fertiliztion incresed corn grin P concentrtion over the control only t loction 2 (Tle 2.3 nd 2.5). None of the other loctions ws ffected y fertiliztion. Across loctions 1 nd 3, fertiliztion did not increse grin P concentrtion, which cn e explined y high soil test P levels t these two loctions (Heckmn et l., 2003). Across loctions 2 nd 4 nd cross ll loctions rodcst lone or with strter incresed P concentrtion on the grin wheres strter lone did not chnge grin P concentrtion (Figure 15

27 2.4). Although grin P concentrtion ws incresed t loction 2, grin P removl ws not ffected y fertiliztion (Tle 2.3). None of the other loctions showed ny effect of fertiliztion on P removl. Across loctions 2 nd 4 only rodcst incresed P removl y the grin (Figure 2.4c). This higher removl ws due primrily to incresed P concentrtion in the grin. Across ll loctions, there ws no significnt tretment effect on P removl showing tht higher nutrient concentrtion in the grin does not necessrily generte higher P removl. Grin K concentrtion ws ffected y fertiliztion t three loctions (1, 2 nd 4) (Tle 2.3). At loction 1, rodcst ppliction decresed K concentrtion in the grin compre to the control nd strter lone (Tle 2.5). On the other hnd t loctions 2 nd 4 grin K concentrtion ws incresed y fertiliztion. Across loctions 1 nd 3, the response is similr to loction 1 (Figure 2.4). Across loctions 2 nd 4, rodcst tretments significntly incresed grin K concentrtion over the control. Anlysis cross ll loctions, however, shows no effect of fertiliztion on grin K concentrtion. Only loction 1 hd grin K removl ffected y fertiliztion. Similrly to grin K concentrtion, rodcst fertiliztion decresed grin K removl t loction 1 nd cross loctions 1 nd 3 (Figure 2.4d). Anlysis cross loctions 2 nd 4 nd ll loctions showed no significnt differences etween the tretments on grin K removl. These results gree with those of Clover nd Mllrino (2012), where they found tht potssium fertiliztion seldom incresed grin K concentrtion or K removl. Soyen Brodcst ppliction lone incresed P lef concentrtion over the control t two loctions (1 nd 3) (Tles 2.6 nd 2.7). Strter fter rodcst incresed P concentrtion t ll loctions (Tle 2.7). Across loctions 1 nd 3, only tretments with rodcst fertiliztion incresed P concentrtion in soyen lef (Figure 2.5). Across loctions 2 nd 4 nd cross ll 16

28 loctions, the comintion of strter nd rodcst seems to further increse P concentrtion thn rodcst pplied lone. Strter pplied lone hd no significnt effect on lef P concentrtion. According to Buh t l. (2000), rodcst ppliction with high rtes of P generlly increses lef P concentrtion more often thn strter pplied lone. Fertiliztion tretments did not significntly increse soyen lef K concentrtion t ny loction compre to the control (Tle 2.6 nd 2.7). At loction 1 fertiliztion tretments decresed K concentrtion. Similrly t loction 2, strter lone decresed K concentrtion compre to the control, rodcst tretments showed no significnt chnge on K concentrtion. Across loctions 1 nd 3, there ws no effect of fertiliztion on K concentrtion. Anlysis cross loctions 2 nd 4, strter lone decresed lef K concentrtion wheres rodcst lone nd with strter ws not sttisticlly different thn the control (Figure 2.5). Across ll loctions, oth rodcst nd strter pplied lone decresed lef K concentrtion, while the comintion of oth did not. The lck of response of K lef concentrtion to fertiliztion might e ecuse soils in the study hd high- to very high K levels (Yin nd Vyn, 2002). Trifolite nitrogen concentrtion ws not ffected y fertiliztion t ny loction (Tle 2.6). Across loctions 1 nd 3 however, rodcst ppliction significntly incresed N concentrtion over the control (Figure 2.5c). Across loctions 2 nd 4 nd ll loctions, there ws no tretment effect on nitrogen concentrtion. Soyen yield ws not significntly ffected y fertiliztion t ny loction or cross loctions (Tle 2.6 nd Figure 2.5d). At loction 3, there ws trend of increse on seed yield, where the comintion of strter nd rodcst or rodcst lone incresed yield y 350 kg h -1 over the control (Tle 2.7). At loctions 1, 2 nd 4 soil test P ws clssified s low (<20 mg kg- 1) for corn nd soyen (Leikm et l., 2003). However reserch in other regions of the U.S. 17

29 suggests lower soil test P criticl level for soyen etween 12 nd 18 mg kg -1 (Dodd nd Mllrino, 2005). It is likely tht the criticl soil test P level for soyen is lower thn 20 mg kg -1 which might explin the lck of response of soyen to fertiliztion. These results gree with Buh et l., (2000) nd Rehm nd Lm (2010), who found tht there is no soyen seed yield dvntge of P or K strter or rodcst when soil tests re in the optimum or higher rnges. Soyen seed P concentrtion ws significntly incresed with rodcst ppliction only t loction 1 (Tle 2.6 nd 2.7). Anlysis cross loctions 1 nd 3, 2 nd 4 nd cross ll loctions shows tht the comintion of strter nd rodcst incresed seed P concentrtion over the control or strter lone (Figure 2.6). According to Frmh et l. (2012), phosphorus fertiliztion my increse not only oveground tissue concentrtion ut lso seed P concentrtion. Seed P removl ws not ffected y ny tretment within ech loction (Tle 2.6 nd 2.7). However, cross loctions 1 nd 3 nd ll loctions, P removed y the seed ws incresed with fertiliztion (Figure 2.6c). Across loction 1 nd 3 ny of the fertilizer plcement methods incresed seed P removl over the control, wheres cross ll loctions, only rodcst lone ws sttisticlly different thn the control. Seed K concentrtion ws incresed y rodcst lone or in comintion with strter only t loction 1 (Tle 2.7). Similrly to loction 1, cross loctions 1 nd 3 seed K concentrtion ws incresed only y rodcst tretments (Figure 2.6). Anlysis cross loctions 2 nd 4 nd cross ll loctions, fertiliztion did not significntly ffected seed K concentrtion. Potssium removl through seed ws not ffected y fertilizer ppliction within ech loction nd cross loctions (Figure 2.6d). This result grees with Frmh et l. (2011), who found tht K fertiliztion cn increse oveground tissue ccumultion ut not K removl in the seed, indicting tht K fertiliztion cn increse K cycling from the soil to the plnt which is lter returned to the soil in the form of crop residue. 18

30 Conclusion Fertiliztion frequently incresed corn erly growth. Strter nd rodcst pplied lone generted similr iomss response over the control t ll loctions, showing no dvntge of one plcement over the other. However there ws enefit of pplying strter fter rodcst, since the comintion incresed erly growth over strter nd rodcst lone. Erly plnt P nd K concentrtion, erly N, P nd K uptke, nd er lef P ws generlly incresed with fertiliztion nd more frequently to rodcst lone or in comintion with strter. Corn grin yield ws incresed y strter fertilizer cross loctions under drylnd, no tillge conditions, nd with sidedress N fertilizer. This increse is possile due to nitrogen deficient erly corn plnt, considering tht soils my hve low ville nitrogen for the roots nd ure ws pplied only t V5 growth stge. Therefore strter fertilizer should e recommended for producers using no-till system nd lso for those using sidedress nitrogen fter plnting. Anlyses cross loctions with irrigtion, conventionl tillge, nd pre-plnt N ppliction, there ws no corn yield response. Strter could e used y frmers, however under these conditions nd soils high on P nd K, yield response to strter would seldom occur. Corn grin P concentrtion is frequently incresed when pplying rodcst fertiliztion; however it does not lwys trnslte in higher grin P removl. Grin K concentrtion response to fertiliztion ws inconsistent nd grin K removl ws not ffected y ny tretment. Therefore fertiliztion generlly does not cuse luxury uptke y the corn grin nd my increse nutrient P nd K cycling, since the excess nutrient sored y the plnt would lter e returned to the soil with the crop residue. Brodcst lone or in comintion with strter frequently incresed trifolite P concentrtion on soyen. On the other hnd, trifolite K concentrtion did not increse with ny fertiliztion tretment. Soyen yield ws not significntly ffected y fertiliztion t ny 19

31 loction or cross loctions. Thus rodcst or strter fertilizer would not e recommended to increse yield for the soil test P nd K levels found in this study. Soyen seed P concentrtion nd removl ws incresed y rodcst ppliction even with no soyen yield response to fertiliztion, wheres seed K concentrtion nd removl ws not ffected y tretments. Brodcst P fertiliztion resulted in phosphorus luxury uptke y soyen seeds nd therefore, in order to increse fertilizer use efficiency, rodcst P ppliction on soyens should e used only on soils testing elow the optiml level. References Aendroth, L.J., R.W. Elmore, M.J. Boyer, nd S.K. Mrly Corn Growth nd Development. PMR Iow Stte Univ. Ext., Ames. Bermudez, M., nd A.P. Mllrino Yield nd erly growth responses to strter fertilizer in no-till corn ssessed with precision griculture technologies. Agron J. 94: Borkert, C.M., nd S.A. Brer Predicting the most eficient phosphorus plcement for soyens. Soil Sci. Soc. Am. J. 49: Buh, S.S.J., T.A. Polito, nd R. Killorn No-tillge corn hyrids response to strter fertilizer. J. Prod. Agr. 12: Buh, S.S.J., T.A. Polito, nd R. Killorn No-tillge soyen response to nded nd rodcst nd direct nd residul fertilizer phosphorus nd potssium pplictions. Agron. J. 92: Bullen, C. W., R.J Soper, nd L.D. Biley Phosphorus nutrition of soyens y plcement of fertilizer phosphorus. Crop Sci. 63:

32 Bullock, D.G., F.W. Simmons, I.M. Chung, nd G.I. Johnson Growth nlysis of corn grown with or without strter fertilizer. Crop Sci. 33: Bundy, L.G., nd T.W. Andrski Strter fertilizer response on high nd very high testing soils. Better Crops with Plnt Food. 85:3-5. Bundy, L.G., H. Tunney, nd A.D. Hlvorson Agronomic spects of phosphorus mngement. p In J. T. Sims nd A. N. Shrpley, (ed.). Phosphorus: griculture nd the environment. ASA, CSSA nd SSSA, Mdison, WI. Crson, P.L Recommended potssium test. p In W. C. Dhnke, (ed.). Recommended chemicl coil test procedures for the North Centrl Region. North Centrl Region Pul. 221 (rev.). N.D. Agric. Exp. Stn., Frgo, ND. Ching, P.C., nd S.A. Brer Evlution of temperture effects on K uptke y corn. Agron. J. 71: Hch Co Intructionl mnul. Digesdhl digestion pprtus model Boulder, Co. Coms, S.M. nd M.V. Nthn Soil orgnic mtter. p In J. R. Brown (Ed.), Recommended chemicl soil test procedures for the North Centrl Region. North Centrl Region Pul. 221 (rev.). Missouri Agric. Exp. Stn., Columi. Dodd, J.R. nd A.P. Mllrino Soil test phosphorus nd crop grin yield responses to long-term phosphorus fertiliztion for corn-soyen rottions. Soil Sci. Soc. Am. J. 69:

33 Eckert, D.J., nd J.W. Johnson Phosphorus fertiliztion in no-tillge corn production. Agron. J. 77: Frmh, B.S., F.G., Fernndez, nd E.D. Nfziger No-till nd strip-till soyen production with surfce nd susurfce phosphorus nd potssium fertiliztion. Agron. J. 103: Frmh, B.S., F.G., Fernndez, nd E.D. Nfziger Soyen seed composition, oveground growth, nd nutrient ccumultion with phosphorus nd potssium fertiliztion in no-till nd strip-till. Agron. J. 104: Fixen, P.E., T.W. Bruulsem, T.L. Jensen, R.M. Mikkelsen, S.T. Murrel, nd S.B. Phillips et l The fertility of North Americn soils. Better Crop With Plnt Food. 94(4): 6-8. Frnk, K., D. Beegle, nd J. Denning Phosphorus. p In J. R. Brown (Ed.), Recommended chemicl soil test procedures for the North Centrl Region. North Centrl Region Pul. 221 (rev.), Missouri Agric. Exp. Stn., Columi. Hm, G.E., W.W. Nelson, S.D. Evns, nd R.D. Frzier Influence of fertilizer plcement on yield response of soyens. Agron J. 65: Hvlin, J.L., S.L. Tisdle, J.D., Beton, nd W.L. Nelson Soil Fertility nd Fertilizers. 7th ed. Person Eduction. Heckmn, J.R., J.T. Sims, D.B. Beegle., F.J. Cole, S.J. Herert., nd T.W. Bruulsem et l Nutrient removl y corn grin hrvest. Agron. J. 95:

34 Howrd, D.D., M.E. Essington, nd J. Logn Long-term rodcst nd nded phosphorus fertiliztion of corn produced using two tillge systems. Agron. J.94: Howrd, D.D., nd D.D. Tyler Comprison of surfce pplied phosphorus nd potssium rtes nd in-furrow fertilizer comintions for no-till corn. J. Fert. Issues. 4: Howrd, D.D., nd M.D. Mullen Evlutionof in-furrow nd nded strter N P K nutrient comintions for no-tillge corn production. J. Fert. Issues. 8: Kiser, D.E., A.P. Mllrino, nd M. Bermudez Corn grin yield, erly growth, nd erly nutrient uptke s ffected y rodcst nd in-furrow strter fertiliztion. Agron. J. 97: Ketcheson, J.W Effect of controlled ir nd soil temperture nd strter fertilizer on growth nd nutrient composition of corn (Ze mys L.) Soil Sci. Soc. Am. J. 32: Leikm, D.F., R.E Lmond, nd D.B. Mengel Soil test interprettion nd fertilizer recommendtion. MF Knss Stte Univ. Ext., Mnhttn. Mcky, A.D., nd S.A. Brer Soil moisture effects on root growth nd phosphorus uptke y corn. Agron. J. 77: Mllrino, A.P., nd R. Borges Deep nding phosphorus nd potssium for no-till corn nd soyens. p In Proc. Conf. North Centrl Extension-Industry Soil Fertility, 27 th, St. Louis, MO Nov Univ. of Nersk-Lincoln, Lincoln, NE. Mllrino, A.P., N. Bergmnn, nd D.E. Kiser Corn responses to in-furrow phosphorus nd potssium strter fertilizer pplictions. Agron. J. 103:

35 Mllrino, A.P., S.R. Brcos, J.R. Prter, nd D.J. Wittry Timing of Brodcst Phosphorus Fertiliztion for No-Till Corn nd Soyen. Soil Sci. Soc. Am. J. 73: Mllrino, A.P., J.R. We, nd A.M. Blckmer Corn nd soyen yields during 11 yers of phosphorus nd potssium fertiliztion on high-testing soil. J. Prod. Agr. 4: Mengel, D.B., S.E. Hwkins., nd P. Wlker Phosphorus nd Potssium plcement for notill nd spring plowed corn. J. Fert. Issues. 5: Murphy, J., nd J.P. Riley A modified single solution method for determintion of phosphte in nturl wters. Anl. Chim. Act 26: Pedersen, P Soyen growth nd development. PM Iow Stte Univ. Ext., Ames. Plenet, D., nd G. Lemire Reltionships etween dynmics of nitrogen uptke nd dry mtter ccumultion in mize crops. Determintion of criticl N concentrtion. Plnt Soil. 216: Rndll, G.W., nd R.G. Hoeft Plcement methods for improved efficiency of P nd K fertilizers: review. J. Prod. Agr. 1: Rndll, G.W., S.D. Evns, nd T.K. Irgvrpu Long-term P nd K pplictions: II. Effect on corn nd soyen yields nd plnt P nd K concentrtions. J. Prod.Agr. 10: Rehm, G.W., nd J.A. Lm Corn response to fluid fertilizers plced ner the seed t plnting. Soil Sci. Soc. Am. J. 73: