MICRONUTRIENTS FERTILIZATION FOR CORN AND SOYBEAN: A RESEARCH UPDATE

MICRONUTRIENTS FERTILIZATION FOR CORN AND SOYBEAN: A RESEARCH UPDATE Antonio P. Mallarino 1, James J. Camberato 2, Daniel E. Kaiser 3, Carrie A.M. Laboski 4, Dorivar A. Ruiz-Diaz 5, an Tony J. Vyn 2 1 Iowa State University, 2 Purue University, 3 University of Minnesota, 4 University of Wiscoin, 5 Kaas State University INTRODUCTION Essential plant nutrients such as boron (B), copper (Cu), iron (Fe), manganese (Mn), molybenum (Mo), zinc (Zn), an others are absorbe by crops in very small amounts an are referre to as micronutrients. A eficiency can have a large impact on crop yiel, however, because they perform important physiological functio. The soil parent material an soil formation processes over time along with effects of soil moisture, aeration, an temperature can significantly influence the amount of plant-available micronutrients. These factors make much more ifficult the calibration an use of iagnostic tools such as soil an plant-tissue testing than for P or K. Micronutrients eficiencies in corn an soybean are not wiesprea in the northcentral region with few exceptio. Table 1 summarizes conitio in which eficiencies woul be most likely. Overall, eficiencies ten to occur in sany an high-ph calcareous soils that are common only in some regio of some states. However, in recent years farmers an crop coultants have been asking many questio about possible yiel loss ue to eficiency of micronutrients because of increasing crop yiels an wor of eficiencies in other regio of the US. For this reason, several stuies have been conucte in several states of the region in recent years. This article highlights results from recent or ongoing stuies conucte in Iniana, Iowa, Kaas, Minnesota, an Wiscoin. INDIANA STUDIES Northwest Iniana soils high in organic matter with near neutral to basic ph have been known to be Mn eficient since the 19 s (Conner, 1932; 1933). The positive yiel respoe of soybean to soil an foliar applicatio of Mn fertilizer was first reporte in the 19 s (Steckel, 1947). Recent research has been evaluating respoe to Mn fertilization with higher yieling soybean varieties, ifferent Mn fertilizers an application techniques, an the possible interaction of Mn nutrition with glyphosate use (Duke et al., 12). Fiel research from 07 to 09 focuse on wie-row ( inches) soybean respoe to starter-bane an foliar Mn applicatio when varying glyphosate applicatio (none, pre alone, pre plus post, an pre plus two post) were mae (Xia, 09). In an experiment conucte at three locatio with five replicatio in 07 an 08 (with mean soil-test Mn ranging from 2.8 to 13.7 ppm), we conclue that (a) glyphosate application treatments never reuce leaf Mn concentratio in soybean, (b) that starter-bane Mn applicatio at 0, 2.5, an 5.0 lb/acre ha no influence on leaf Mn concentratio, but i increase see Mn concentratio, (c) that foliar Mn application (0.50 lb/acre) substantially increase leaf Mn concentratio for a short time following application, () that neither foliar nor bane applicatio increase see yiel significantly, an (e) that trifoliate leaf Mn concentratio were often highly correlate with iniviual plot soil ph (negatively) an Mehlich-3 extractable soil Mn (positively). In these etaile stuies we confirme that lack of soybean respoe to starter Mn when North Central Exteion-Inustry Soil Fertility Conference. 15. Vol. 31. Des Moines, IA. Page 44

applie alone. However, respoes to ban or foliar applie Mn sometimes are observe when starter fertilizer containing N an P is use. Soybean yiel was increase 6 bu/acre by Mn applie foliar, in a 2x2 ban with 10-34-0, or both foliar an bane in a 07 stuy conucte on a soil (ph-6.5, OM-5%, CEC, 22 meq/100g, Mehlich 3 Mn-12 ppm) known to show Mn eficiency. Baning 10-34-0 alone i not increase yiel. Leaf tissue Mn at first flower was unaffecte by fertilizer treatment, averaging 15 ppm which is coiere eficient. In a secon year on a similar soil there was no effect of Mn applie by any metho. In more recent Mn research, we have focuse on evaluating oler an experimental proucts for foliar applicatio. We are now focuse on expaning the number of replicatio (eight or more) to help separate treatments statistically in the context of fiel variability an the sometimes small (5-15%) yiel gai that sometimes occur. Weather conitio have a huge impact on plant uptake of soil Mn. As an example, the variability in soybean yiel respoes to foliar applicatio of Mn in Iniana is illustrate in Table 2. In one case (Wanatah) a 5-7 bushel yiel respoe was note for applying foliar Mn proucts twice. In the other case (LaCrosse), the same proucts/rates applie to the same soybean variety prouce a significantly positive respoe only after the single application, an there was a yiel reuction in some treatments for the secon foliar application. IOWA STUDIES Iowa research with micronutrients from the 1960s until 1990s showe no corn an soybean respoe to fertilization with several micronutrients, except isolate corn respoes to Zn only in some soils that teste less than 0.9 ppm DTPA Zn an soybean respoe to Mo in extremely aciic soils which shoul have been lime. More recent research by Bickel an Killorn (07) at 12 Iowa fiels showe some small yiel increases an ecreases from bane Zn application to corn that were not relate to soil-test DTPA Zn levels. Three projects were conucte from 12 through 14 that encompasse more than Iowa soil series. Two projects evaluate foliar fertilization at fiels manage with no-till or chisel-plow/isk tillage. Conventional-plot trials were conucte at 46 soybean fiels an 11 corn fiels in which treatments were a control; B, Cu, Mn, or Zn applie separately; an a mixture. Commercial fertilizers base on boric aci for B an EDTA for the other nutrients were spraye at the V5-V6 growth stage of both crops an again at the soybean R2/R3 stage or corn V8-V10 stage. Total amounts applie were 0.16, 0.08, 0.33, an 0.50 lb/acre of B, Cu, Mn, an Zn. Replicate strip-trials were conucte at 17 soybean fiels an nine cornfiels. Treatments spraye once at the V5-V7 stage were a control an a mixture that applie 0.11, 0.08, an 0.11 lb/acre of B, Mn, an Zn. A thir project evaluate application of granulate B, Mn, an Zn fertilizers to the soil for corn-soybean rotatio at eight sites manage with tillage that were evaluate for three years. Six annual replicate treatments were a control; a mixture of B, Mn, an Zn bane with the planter or broacast an incorporate into the soil; an separate ban applicatio of each micronutrient. All planter-ban micronutrient fertilizers were mixe with MAP an the same starter MAP rate was use for the control an broacast treatments. Boron was applie at 0.5 or 2.0 lb/acre for ban an broacast treatments, respectively, whereas the Mn an Zn rates (sulfates) were 5 lb/acre for the ban an broacast treatments. Soil ph, clay, organic matter, an CEC across all conventional-plot sites were 4.9-7.5, 15-33%, 3.1-8.0%, an 14-36 meq/100 g, respectively (6-inch epth). Soil B was measure by the hot-water metho an was 0.2-1.7 ppm. Soil Cu, Mn, an Zn were 0.3-1.8, 2.1-42, an 0.5-15 ppm by the DTPA metho, which are among methos recommene methos by the north- North Central Exteion-Inustry Soil Fertility Conference. 15. Vol. 31. Des Moines, IA. Page 45

central region committee for soil an plant analysis (NCERA-13). Soil Cu, Mn, an Zn also was measure with the Mehlich-3 metho an were 1.6-5.5, 7-128, an 1.1-32 ppm, respectively. This metho is being use by some laboratories in the region but is not recommene by the NCERA-13 ue to lack of fiel calibratio with yiel respoe. Crop yiel levels varie greatly across the trials ue to the variety of conitio across Iowa uring three years. Soybean yiel range from 25 to 73 bu/acre an corn yiels range from 144 to 255 bu/acre. There were no statistically significant (P 0.05) grain yiel increases from application of any micronutrient at any conventional plot trial with fertilization to the foliage or the soil. Therefore, crop yiels are not shown. Slight foliage burning was observe only for the mixture an at a very few sites. At one soybean foliar fertilization trial there were yiel ecreases from application of Cu alone an the mixture of B, Cu, Mn, an Zn. In contrast, fertilization sometimes increase the micronutrient concentratio in vegetative plant tissue an often in grain (not shown). At the foliar fertilization strip trials, there was a yiel increase at one soybean fiel an a yiel ecrease at one corn fiel (not shown). A lack of yiel respoe i not allow for the ientification of sufficiency values for soil- or tissue-test results. Publishe soil-test interpretatio by some states of the region base on oler research (Buchholz, 1983; Penas an Ferguson, 00; Gerwing an Gelerman, 05; Fernanez an Hoeft, 09; Laboski an Peters, 12; Mallarino et al., 13; Vitosh et al., 1995) preicte a high frequency of respoes for some micronutrients. Corn or soybean yiel respoes from B were expecte at five sites using the lowest suggeste value or at all sites using the highest suggeste value; from Cu an Mn at no site; an from Zn at six sites using the lowest suggeste value or at most sites using the highest suggeste value. These stuies coul not be use to etermine which of DTPA or Mehlich-3 soil-tests for Cu, Mn, an Zn was better because there were no grain yiel increases. However, Fig. 1 shows a goo correlation between DTPA an Mehlich-3 tests for Zn, but poor for Cu an nonexistent for Zn. These results inicate that both tests assess Zn availability similarly but one of them is better for Cu an Mn. The abovegroun portio of corn an soybean plants were sample at the V6 growth stage, mature soybean leaves were sample at the R2-R3 stage, an corn ear-leaf blaes were sample at the R1 stage (silking). As an example, Fig. 2 shows a poor correlation between soybean tissue test results at two growth stages an DTPA Mn but no correlation for DTPA Cu, DTPA Zn, an hot-water B. Results for corn an for the Mehlich-3 test for either crop were similar (not shown). There are no publishe sufficiency levels in the region for tissue tests at the V5-V6 growth stage. Use of publishe sufficiency ranges in some states or elsewhere (Bryson et al., 14) for soybean leaves at miseason preicte no yiel respoes from B or Mn, at 39 sites from Cu, an at two sites for Zn. Interpretatio for corn ear-leaf blaes at silking preicte no yiel respoes from Cu an Mn, an respoes from B at one site an from Zn at one site. Existing interpretatio of tissues tests for B, Mn, an Fe (but not Cu) were better at preicting the lack of yiel respoe in these stuies than the interpretatio for soil tests. Therefore, the Iowa stuies at many fiels showe very unlikely corn an soybean respoe to fertilization with micronutrients, that use of most publishe soil or plant-tissue test interpretatio often have calle for unneee micronutrient fertilization in many fiels. KANSAS STUDIES Four projects were complete (three for soybean an one for corn) from 09-14. One soybean stuy focuse on iron (Fe) eficiency chlorosis (IDC), an targete soil conitio that are prone to IDC (high ph an high calcium carbonate). Seven locatio with a history of IDC in North Central Exteion-Inustry Soil Fertility Conference. 15. Vol. 31. Des Moines, IA. Page 46

soybean were selecte. The stuy coiste of a factorial esign with three foliar treatments (two chelate Fe fertilizer forms an no foliar), two see-applie Fe fertilizer treatments (with an without chelate ortho-ortho EDDHA fertilizer), an two ifferent varieties (a nontolerant an tolerant commercial variety). Soil ph varie from 8.1-8.5, calcium carbonate equivalent from 5-14% an organic matter from 1.7-2.7%. Plant population, chlorophyll meter (CM) reaings (V3 an V6 growth stage), plant height at maturity, an grain yiel were measure. Foliar Fe application i not affect any plant parameter, however, the use of see-applie chelate o-o- EDDHA Fe fertilizer significantly increase CM reaings at the V3 an V6 growth stages, plant height at maturity, an grain yiel across all locatio (Fig. 3). Given soil conitio conucive to the evelopment of severe IDC, see-applie chelate o-o-eddha Fe fertilizer increase yiels by approximately 55% for both varieties (Liesch et al., 11). Results from this stuy suggest that if supplemental see-applie Fe fertilizer will be use, proucers shoul choose the best varieties primarily base on yiel potential for the region. Furthermore, chelate o-o- EDDHA Fe fertilizer applie in contact with the soybean see can contribute to significant yiel increase, however foliar applicatio showe no yiel respoe. A secon stuy (incluing both corn an soybean) inclue micronutrient fertilizer ble applie at planting to fiels without a history of eficiencies, in combination with N-P-K starter fertilizers as well as foliar applicatio on corn an soybean. Eight site years (four sites for each crop) were establishe to evaluate combinatio (factorial arrangement) of liqui starter an foliar fertilizers that contain N-P-K with an without a blen of micronutrients (Fe, Mn, Zn, Cu, an B) uner high yieling irrigate conitio. Starter fertilizer treatments inclue: control; N- P-K only; an N-P-K plus 0.5 lb/acre of each micronutrient. Foliar fertilizer treatments inclue: control; N-P-K fertilizer at 2, 1, an 2 lb/acre of N, P, an K; an N-P-K plus 0.2 lb/acre of each micronutrient. Foliar applicatio were mae at the R2 an V6 V8 growth stages in soybean an corn, respectively. No early growth or yiel increases were attribute to the micronutrient blen in corn or soybean. Foliar fertilization i not increase yiel in corn or soybean. Starter fertilizers showe more tenencies to increase yiel than i foliar fertilization in corn an soybean, however with no statistically ifferent values (Table 3). A thir soybean stuy was complete at ten locatio using a ranomize complete-block esign with four replicatio. This stuy focuse on a range of soybean yiel potential, but with no history of visual micronutrient eficiency. Treatments coiste of an unfertilize control, micronutrient fertilizer as iniviual nutrient for B, Cu, Mn, S an Zn applie broacast preplant, in aition to a combination of these nutrients using two ifferent placements (broacast an ban). All fertilizer sources were ry an sulfate-base, except for liqui fertilizer applie as ban placement. Sulfur an micronutrient fertilization showe no significant effect on soybean yiel; except for one location (Sany, 80% san) with approximately 6 bu/acre increase of the broacast mix compare to the control. Zinc fertilization ha significant effects on tissue an grain zinc concentration. Copper in tissue was below sufficiency ranges in almost all sites, therefore this nutrient sufficiency ranges must be revise for further stuies. MINNESOTA STUDIES The most commonly stuie micronutrient in soybean in Minnesota has been Fe ue to the prevalence of iron eficiency chlorosis (IDC) in areas of central an western Minnesota. Past research has emotrate respoes to Fe when applie as o-o-eddha (ortho-ortho-eddha) chelate isomer. Ranall (1977) outline foliar application of o-o-eddha at early vegetative stages for the correction of IDC in soybean. However, o-o-eddha fertilizers were traitionally North Central Exteion-Inustry Soil Fertility Conference. 15. Vol. 31. Des Moines, IA. Page 47

cost prohibitive for use in soybean prouction. Recent avances have lowere the cost of prouction making o-o-eddha more cost effective to use for correction of IDC. Many soybean proucers are currently applying o-o-eddha irectly on the see in IDC prone areas. Figure 4 summarizes ata collecte from five fiel locatio in west-central Minnesota prone to IDC. Rates of 0, 1, 2, an 3 lb of Soygreen (West Central Inc., Willmar, MN) were applie irectly on the soybean see in 0, 2, 4, or 6 gallo of a water an Soygreen mixture at the time of planting. Soygreen is a 6% Fe fertilizer source where 80-83% of the Fe is chelate as o-o-eddha. Average respoe across locatio inicate that Soygreen increase soybean grain yiel by 3-4 bu/acre. Statistically, the 3 lb rate increase yiel over the control an the 2 lb rate was no ifferent than the control or the 3 lb rate. Of the five sites, two exhibite the greatest respoe an there was very little to no ifference at the remaining three sites (not shown). While proucts like Soygreen have shown promise for reucing IDC, targeting areas with the greatest severity of IDC are suggeste ue to the cost of the prouct an the lack of impact on soils not prone to IDC (Kaiser et al., 14). Recent stuies with other micronutrients have shown very little benefit for application to soybean. Twelve locatio were establishe across Minnesota between 11 an 12 to stuy the impact of MicroEssentials-SZ [MEZ (Mosaic, Plymouth, MN)] on soybean. The prouct MEZ was broacast applie at a rate of 0 lb. or prouct per acre which supplie 24 lb. N, 80 lb. P 2 O 5, lb. S, an 2 lb. Zn per acre. In aition to the control an 0 lb. MEZ rate, three treatments were inclue which omitte one or more nutrients (N only, N plus P, an N, P, plus S) but supplie the same amount of nutrient as was applie with the MEZ. Across the twelve locatio there was no effect of Zn on soybean grain yiel (Fig. 5). When a respoe i occur within a location is was either ue to the N or P applie in the MEZ an never S or Zn (ata not shown). In all cases soil test Zn was above the threshol (0.75 ppm DTPA extractable Zn) coiere sufficient for crops such as corn which are more susceptible to Zn eficiency). In a more recent stuy, soybean yiel was increase by the use of 10 lb of Zn broacast in the spring at one of twelve locatio which ha a Zn soil test less than 0.5 ppm (DTPA). Aitional work has been conucte applying 10 lb of Zn, 10 lb of Mn, 0.5 lb of Mo, an 2lb of B broacast in the spring prior to planting. Twelve locatio were stuie from 11 to 13 comparing a non-fertilize control to a treatment where all nutrients were applie an iniviual treatments where one of the nutrients was omitte. Data were combine across the 12 locatio an is summarize in Fig.6. There was no positive impact of any of the treatments iniviually among locatio or across all locatio. The only significant ifference occurre at a few locatio where the 2 lb B treatment reuce yiel. This reuction was not reflecte in the yiel mean across the locatio. The ata provie inicate that micronutrients other than Fe will not increase the yiel of soybean for nearly all fiels across Minnesota. WISCONSIN STUDIES A three-year research stuy was conucte with the following objectives: i) to quantify the effect of glyphosate on Mn availability in glyphosate resistant soybean systems; an ii) to evaluate soybean respoe to starter an/or foliar Mn applicatio (Laboski et al., 12). Fiel research stuies were establishe at four on-farm locatio in Walworth County near East Troy in 08, Doge County near Hubbleton an Jefferson County near Watertown in 09, an in Outagamie County north of New Lonon in 10 (Table 4). Treatments coiste of: i) three soybean variety/herbicie combinatio incluing a non-glyphosate resistant (Non-GR) soybean variety (Dairylan DSR2118) with conventional herbicie, a glyphosate resistant (GR) variety North Central Exteion-Inustry Soil Fertility Conference. 15. Vol. 31. Des Moines, IA. Page 48

(Asgro AG24) with conventional herbicie, an a GR variety with glyphosate herbicie; ii) two rates of Mn (as MnSO 4 ) in a 2 x 2 starter fertilizer ban incluing 0 an 5 lb Mn/a; an iii) four levels of foliar Mn (as MnSO 4 ) rate an timing incluing none, 1.25 lb Mn/a at the R1 growth stage, 1.25 lb Mn/a at the R3 growth stage, an 1.25 lb Mn/a at the R1 an R3 growth stages. Treatments were replicate four times. Soybean leaf samples were collecte from select treatments at several times throughout the season incluing: i) at the R1 growth stage just prior to R1 foliar application; ii) about 10-ays post R1 foliar application; iii) at the R3 growth stage just prior to R3 foliar application; an iv) about 10-ays post R3 foliar application. Samples coiste of collecting 10 leaves (uppermost fully-evelope trifoliate an petiole) from the center two rows within the plot. Leaf samples were analyze for Mn concentration. At all locatio tissue Mn concentratio at the R1 growth stage were less than current UW sufficiency range (54 to 0 ppm) (Schulte et al. 00); thus a yiel respoe to Mn application woul be expecte. Ten ays after 1.25 lb Mn/acre was applie foliarly at R1, tissue Mn concentratio were greater compare to R1 at all locatio. There was a significant effect of variety/herbicie on tissue Mn concentratio 10 ays post R1 application at all locatio except Walworth. Tissue Mn concentratio at the R3 growth stage were generally less than at R1 for plots that ha not receive any foliar Mn application at R1 at all locatio except at Outagamie. Tissue Mn concentratio at Outagamie were about ouble the concentratio at the other locatio at the R3 sampling time. At the R3 sampling time there were some significant ifferences between variety/herbicie at Jefferson an Outagamie where GR/Conv an Non- GR/Conv ha significantly greater tissue Mn, respectively. At all locatio, tissue Mn concentratio 10 ays post R3 were significantly affecte by foliar Mn application. No foliar application an application of Mn at R1 ha significantly lower tissue Mn concentratio compare to foliar applicatio at R3, an R1 + R3. Application of foliar Mn at R1 resulte in tissue Mn concentratio initially increasing through 10 ays post R1 an then ecreasing at Walworth an Doge. At Jefferson, foliar application of Mn at R1 resulte in tissue Mn initially increasing to 10 ays post R1, then ecreasing to R3 an then remaining steay or slightly increasing through 10 ays post R3. Outagamie often showe tre in tissue Mn ata that was not coistent with other locatio. This may be the result of soil test Mn being optimum an the soil being somewhat poorly raine compare to other sites which were poorly or very poorly raine. Soybean yiels range from 27 to 59 bu/acre across the locatio. Manganese application an variety/wee management ha minimal effects on soybean yiel over all locatio. At Jefferson, there was an interaction between foliar Mn applicatio an variety/herbicie management. Foliar applicatio of Mn at R1 significantly increase yiel compare to foliar applicatio at R3 an no foliar application for the GR/Conv only; there were no ifferences between foliar Mn treatments in Non-GR/Conv an GR/glyphosate variety/herbicie treatments. At Doge an Jefferson there was a significant three-way interaction between variety/herbicie, starter, an foliar treatments. When starter Mn was applie to the GR/glyphosate, yiels were greater than when foliar Mn was applie at R1 + R3 (51 an 52 bu/a) compare to no foliar application (45 an 48 bu/a). However, when no starter Mn was applie to this variety/herbicie treatment, the tren was reverse; yiels were lower where Mn was applie at R1 + R3 (46 an 43 bu/a) compare to no foliar application (52 an 51 bu/a). These tre for the GR/glyphosate treatment were not observe for the other variety/herbicie treatments. There was no correlation between yiels achieve an tissue Mn concentratio 10 ays post R3 at any locatio. This is not surprising because there were generally no significant yiel ifferences. North Central Exteion-Inustry Soil Fertility Conference. 15. Vol. 31. Des Moines, IA. Page 49

In conclusion, the Wiscoin stuies showe that application of Mn in starter or as foliar at R1, R3, or R1 + R3 i not increase soybean yiel at locatio where Mn was expecte to be a problem base on low or optimum soil test levels. At all of these locatio, R1 tissue Mn concentratio were coiere low base on current UW plant analysis interpretation guielines; however, there were no visual Mn eficiency symptoms. Also, the results i not suggest that glyphosate resistant soybean varieties are more seitive to Mn, or benefit from foliar applicatio after glyphosate application. These ata suggest that a tissue Mn sufficiency concentration range of 54 to 0 ppm may be too high because all sites ha R1 tissue Mn concentratio below this range but i not respon to Mn applicatio. These ata also suggest that even on soils where Mn eficiency has the potential to be a problem (low Mn soil test or ph over 6.9 on soils with organic matter greater than 6.0%), if no visual eficiency symptoms are apparent, then application of Mn is likely not economical. OVERALL CONCLUSIONS The results of recent research with micronutrients in five states of the north-central region confirme that many of our soils have sufficient amounts of micronutrients for corn an soybean prouction an that there is a great eal of uncertainty concerning the value of current interpretatio of soil an tissue testing. Data from the stuies iscusse here showe that high yieling crops can remove higher amounts of micronutrients with the harveste grain. However, yiel potential alone cannot be use as inicator for micronutrient fertilizer requirement, an ultimately specific soil conitio will etermine the potential yiel respoe. Furthermore, scarce yiel respoes to some nutrients were observe in small areas of some states with specific soil conitio. Therefore, ecisio about micronutrient fertilization coul be better mae by targeting fiels in regio with soils which traitionally have been ientifie with more likelihoo of yiel respoe such as sany, calcareous, organic, or severely eroe soils. REFERENCES CITED Bickel, A. an Killorn, R. 07. Respoe of corn to bane zinc sulfate fertilizer in fiels with variable soil ph. Commun. Soil Sci. Plant Anal. 38:1317-1329. Bryson, G.M., Mills, H.A., D.N. Sasseville, J.B. Jones Jr., an A.V. Barker. 14. Plant analysis hanbook III: A guie to sampling, preparation, analysis, an interpretation an use of agronomic an horticultural crop plant tissue. Micro-Macro Publishing, Inc. Athe, GA. Buchholz, D.D. 1983. Soil test interpretatio an recommenatio hanbook. Dept. Agron. University of Missouri, Columbia. Accesse 2 July 14 at http://aes.missouri.eu/pfcs/soiltest.pf. Conner, S.D. 1932. Factors affecting manganese availability in soils. Jour. Amer. Soc. Agron. 28:726-733. Conner, S.D. 1933. Treatment of muck an ark sany soils. In. Agr. Ext. Ser. Leaflet 179. Duke, S.O., J. Lyon, W.C. Koskinen, T.B. Moorman, R.L. Chaney, an R. Hammerschmit. Glyphosate effects on plant mineral nutrition, crop rhizosphere microbiota, an plant isease in glyphosate-resistant crops. J. Agric. Foo Chem. 60:10375-10397. Fernanez, F.G. an R.G. Hoeft. 09. Managing soil ph an crop nutrients. In: Illinois Agronomy Hanbook. Gelerman, R.H., an A.P. Mallarino. 12. Soil sample preparation. In: Recommene chemical soil test proceures for the North Central Region. North Central Regional Publ. No. 221 (Rev.). Missouri Agric. Exp. Stn. Columbia, MO. p. 5-7. North Central Exteion-Inustry Soil Fertility Conference. 15. Vol. 31. Des Moines, IA. Page 50

Gerwing, J., an R. Gelerman. 05. Fertilizer recommenatio guie. South Dakota State University Exteion. EC750. Accesse 2 July 14 at http://pubstorage.sstate.eu/agbio_publicatio/articles/ec750.pf. Kaiser, D.E., J.A. Lamb, P.R. Bloom, an J.A. Hernanez. 14. Management strategies for iron eficiency chlorosis assesse using replicate strip trials. Agron J. 106:1963-1974. Laboski, C.A.M., T. Anraski, S. Conley, J. Gaska. 12. Effect of soybean variety, glyphosate use, an manganese application on soybean yiel. Proc. Wiscoin Crop Management Conf. 51:49-64. Laboski, C.AM. an J.B. Peters. 12. Nutrient application guielines for fiel, vegetable, an fruit crops in Wiscoin. University of Wiscoin Exteion. A2809. Accesse 2 July at http://learningstore.uwex.eu/assets/pfs/a2809.pf. Liesch, A. M., D. A. Ruiz Diaz, K. L. Martin, B. L. Olson, D. B. Mengel, an K. L. Roozeboom. 11. Management Strategies for Increasing Soybean Yiel on Soils Susceptible to Iron Deficiency. Agron. J. 103:1870-1877. Mallarino, A.P., J.E. Sawyer, an S.K. Barnhart. 13. A general guie for crop nutrient an limestone recommenatio in Iowa. Iowa State Univ. Exteion an Outreach. PM1688. Accesse 2 July 14 at http://www.agronext.iastate.eu/soilfertility/nutrienttopics/limesoilph.html. Ranall, G.W. 1977. Correcting iron chlorosis in soybea. Soils Fact Sheet No. 27. Univ. of MN Ext., Saint Paul. Schulte, E.E., K.A. Kelling, J.B. Peters, an S.M. Combs. 00. Plant analysis interpretatio use in the revise Wiscoin Program. New Horizo in Soil Science No. 7-00. Dept. of Soil Science, Univ. of Wiscoin-Maison. Steckel, J.E. 1947. Manganese fertilization of soybea in Iniana. Soil Sci. Soc. Am. J. 11:345-348. Vitosh, M.L., J.W. Johon, an D.B. Mengel. 1995. Tri-state fertilizer recommenatio for corn, soybea, wheat, an alfalfa. Exteion Bulletin E-2567. Accesse 2 July 14 at https://www.exteion.purue.eu/extmeia/ay/ay-9-32.pf. Xia, Yanbing. 09. Soybean plant respoes to glyphosate an manganese in glyphosateresistant prouction systems. MS Thesis, Purue University. Major Avisor: T.J. Vyn. TABLES Table 1. Traitional views concerning likelihoo of crop micronutrients eficiency in the north-central region. Micronutrient Soil Conitio Most Seitive Crop Boron (B) Sany or highly weathere soils low in organic matter, rought Alfalfa, clovers Copper (Cu) Aci organic or very sany soils Wheat, oats, corn Iron (Fe) Calcareous soils (ph>7.0) Soybean Manganese (Mn) Organic soils with ph>5.8 an Soybean, wheat, oats, calcareous soils (ph>7.0) sugar beets Zinc (Zn) Sany or very low organic matter or calcareous soils (ph >7.0) Corn Molybenum (Mo) Sany or very aci soils (ph< 5.5) Soybean, legumes North Central Exteion-Inustry Soil Fertility Conference. 15. Vol. 31. Des Moines, IA. Page 51

Table 2. Soybean yiel respoe in Iniana to commercial foliar Mn proucts applie in a separate pass 5- ays after post-emergent glyphosate application(s) in 11. Soybean Yiel Application(s) Foliar Treatment Wanatah LaCrosse -------- bu/acre ------ Control.3 c 38.5 bc July 21 EDTA Mn @32 oz/acre 42.8 bc 43.3 a Pro Mn @ 38 oz/acre 44.6 abc 43.2 a ProMn @ 76 oz/acre 44.6 ab 43.3 a ManniPlex for Bea @ 60 oz/acre 44.8 abc.9 ab July 21 + August.5 EDTA Mn @32 oz/acre 45.7 a 41.8 ab Pro Mn @ 38 oz/acre 46.4 a 39.3 b ProMn @ 76 oz/acre 47.0 a.1 ab ManniPlex for Bea @ 60 oz/acre 45.7 a 35.1 c LSD (0.05) 2.6 3.6 Yiels are averages over two glyphosate treatments (at V4 stage alone or at V4 plus R1 stages). Soils were sany loam to loam. Table 3. Mean yiel respoe of corn an soybean to starter an foliar fertilization in Kaas. Starter Foliar Crop Site Control N-P-K N-P-K-M Control N-P-K N-P-K-M ------------------------------------- bu/acre ----------------------------- Corn 1 228 236 226 2 231 229 2 212 212 9 213 212 8 3 224 229 2 226 228 229 4 229 244 237 237 239 234 Soybean 1 55 58 57 59 56 55 2 63 63 64 64 62 64 3 42 41 39 42 41 4 64 70 71 68 69 68 Mean values are not statistically ifferent at the 0.10 probability level Fertilizer containing N, P, an K; M, micronutrient blen of Fe, Mn, Zn, Cu, an B. North Central Exteion-Inustry Soil Fertility Conference. 15. Vol. 31. Des Moines, IA. Page 52

Table 4. Experimental conitio at four Wiscoin locatio. County an Year Information Walworth 08 Doge 09 Jefferson 09 Outagamie 10 Soil an texture Parent material Sebewa silt loam Loamy outwash over calcareous sany an gravelly outwash. Granby fine sany loam Sany outwash or glaciolacustrine eposits on outwash or lake plai. Wacousta silty clay loam Silty stratifie lacustrine eposits. Shiocton silt loam Silty lacustrine eposits over stratifie sany an silty lacustrine eposits. Soil rainage Poorly raine Poorly raine Very poorly raine Soil group B E B D ph 7.2 8.1 7.8 7.2 Org. matter, % 3.1 5.2 6.1 2.6 Bray 1 P, ppm 123 (EH) 2 (13 ppm Olsen) 12 (H) 19 (H) Bray 1 K, ppm 189 (EH) 68 (O) 109 (O) 73 (L) Mn, ppm 16 (O) 2 (L) 4 (L: organic matter > 6% an ph > 6.9) Somewhat poorly raine 14 (O) Previous crop Corn grain Corn grain Corn grain Corn grain N-P 2 O 5 -K 2 O 0-0-0 lb/a 5-64-60 lb/a 0-0-60 lb/a 0-0-90 lb/a Tillage No-till No-till Spring chisel Spring chisel plow plow Soil test category: L, low; O, optimum; H, high; an EH, excessively high. The soil test P level using the Bray 1 P extract was very low (2 ppm) ue to the high soil calcium carbonate content. The Olsen soil P extract (commonly use in regio with alkaline or highly calcareous soils) was 13 ppm woul be coiere to be in the optimum to high category in Iowa. FIGURES Mehlich-3 Cu (ppm) 4.5 4.0 3.5 3.0 2.5 2.0 Cu - M3 vs DTPA Mn - M3 vs DTPA Zn - M3 vs DTPA Y = 1.68 + 1.01X r 2 = 0.31, P < 0.01 Mehlich-3 Mn (ppm) 1 1 100 80 60 r 2 = 0.03 Mehlich-3 Zn (ppm) 35 25 15 10 5 Y = -0.75 + 2.16X r 2 = 0.95, P < 0.01 1.5 0.0 0.5 1.0 1.5 2.0 2.5 DTPA Cu (ppm) 0 10 50 DTPA Mn (ppm) 0 0 2 4 6 8 10 12 14 16 DTPA Zn (ppm) Fig. 1. Relatiohips across Iowa conventional plot trials soil Cu, Mn, an Zn measure with DTPA an Mehlich-3 test methos. North Central Exteion-Inustry Soil Fertility Conference. 15. Vol. 31. Des Moines, IA. Page 53

Plant B (ppm) Plant Cu (ppm) 44 36 32 28 24 r 2 = 0.08 0.0 0.4 0.8 1.2 1.6 Soil B (ppm) 15 10 5 r 2 = 0.01 Plant Mn (ppm) Plant Zn (ppm) 0 0.0 0.5 1.0 1.5 2.0 Soil DTPA Cu (ppm) Plant at V6 vs Soil Tests 1 100 80 60 Y = 32.3 + 1.36X r 2 = 0.33, P < 0.01 0 10 50 Soil DTPA Mn (ppm) 45 35 25 r 2 = 0.01 0 1 2 3 4 5 6 7 Soil DTPA Zn (ppm) Leaves at R2/R3 vs Soil Tests 65 100 60 r 2 90 Y = 39.7 + 0.53X = 0.01 r 2 = 0.13, P < 0.05 55 80 50 70 45 60 50 35 DTPA Cu Dry vs Cu leaf 25 0.00...60.81.01.21.41.61.8 0 10 50 Soil B (ppm) Soil DTPA Mn (ppm) 12 50 Fig. 2. Relatiohips across Iowa foliar fertilization trials between soybean tissue test results at two growth stages an soil-test results for B (hot-water test), Cu, Mn, an Zn(DTPA test). Leaf B (ppm) Leaf Cu (ppm) 10 8 6 4 r 2 = 0.01 Leaf Mn (ppm) Leaf Zn (ppm) 2 0.0 0.5 1.0 1.5 2.0 Soil DTPA Cu (ppm) 45 35 25 r 2 = 0.01 15 0 1 2 3 4 5 6 7 Soil DTPA Zn (ppm) North Central Exteion-Inustry Soil Fertility Conference. 15. Vol. 31. Des Moines, IA. Page 54

SPAD CM reaing 10 A. c c bc a a ab Foliar FeEDDHA Foliar FeHEDTA No Foliar 0 50 B. a a ab c c bc Height (cm) 10 Grain yiel (bu/acre) 0 10 C. a a ab c c bc 0 Fe Fe Fe Fe Non-tolerant variety Tolerant variety Fig. 3. Chlorophyll meter reaing values, plant height an grain yiel as affecte by soybean variety selection see-applie Fe-EDDHA ortho- ortho fertilizer, an foliar applie chelate Fe (EDDHA an HEDTA). Average across seven site-years. North Central Exteion-Inustry Soil Fertility Conference. 15. Vol. 31. Des Moines, IA. Page 55

Soybean Grain Yiel (bu/ac) 50 48 P<0.10 ab a 46 44 bc c 42 38 36 34 32 0 1 2 3 Soygreen Rate (lb/ac) Yiel (bu/ac) 38.9 38.7 42.2 42.8 Fig. 4. Soybean grain yiel respoe to 0, 1, 2 an 3 lb of Soygreen per acre applie irectly on the soybean see average across five locatio in west-central Minnesota. Soybean Grain Yiel (bu/ac) 55 50 45 35 Yiel (bu/ac) Chk N N+P N+P+S N+P+S+Zn 46.9 47.8 48.0 47.9 47.4 Fig. 5. Soybean grain yiel respoe to 0 lb per acre of MicroEssentials-SZ broacast before planting compare to a non-fertilize control an treatments that omitte one or more nutrients. North Central Exteion-Inustry Soil Fertility Conference. 15. Vol. 31. Des Moines, IA. Page 56

Soybean Grain Yiel (bu/ac) 55 50 45 35 Yiel (bu/ac) Chk -Zn -Mn -Mo -B All 45.7 46.0 46.5 46.3 47.8 Fig. 6. Soybean grain yiel of a non-fertilize control compare to the application of 10 lb of Zn, 10 lb. of Mn, 0.5 lb of Mo, an 2 lb of B broacast an incorporate before planting an treatments where one of the micronutrients (-Zn, -Mn, -Mo, or -B) were omitte. 45.8 North Central Exteion-Inustry Soil Fertility Conference. 15. Vol. 31. Des Moines, IA. Page 57

PROCEEDINGS OF THE 45 th NORTH CENTRAL EXTENSION-INDUSTRY SOIL FERTILITY CONFERENCE Volume 31 November 4-5, 15 Holiay Inn Airport Des Moines, IA PROGRAM CHAIR: John E. Sawyer Iowa State Univ Ames, IA 50011 (515) 294-7078 jsawyer@iastate.eu PUBLISHED BY: International Plant Nutrition Ititute 21 Research Park Way, Suite 126 Brookings, SD 57006 (605) 692-6280 Web page: www.ipni.net ON-LINE PROCEEDINGS: http://exteion.agron.iastate.eu/nce/