Presentation on theme: "Corn Yield Response to Starter P Fertilizer and ‘Avail’ P Fertilizer Enhancer Ron Gehl Sheri Cahill Deanna Osmond Dept. of Soil Science NC State University."— Presentation transcript:
1 Corn Yield Response to Starter P Fertilizer and ‘Avail’ P Fertilizer Enhancer Ron Gehl Sheri Cahill Deanna Osmond Dept. of Soil Science NC State University SSSNC Annual Meeting 2010
2 Average Soil Test Phosphorus 70% medium or above
4 Starter P as a Corn Management Option In some geographic regions, starter P has been shown to increase crop yields even when STP is relatively highResponse dependent on field management, early-season weather, field issuesP availability a concern in many NC soils – need verification of crop response to starter P in NC cropping systems and soils‘New’ products currently marketed to possibly enhance P availability from applied fertilizers
5 Initial P Starter Research Trials in NC Work by Osmond et al. in 2005, 200639 sites at 17 counties for corn; 14 sites at 8 counties for cottonSTP > 100N-only starter vs. N+P starter (20-30 lbs N and/or P2O5 per ac)
8 Is Starter P Necessary on Very High STP Soils? Data from 2005 & 2006 should have shown differences due to the cool, wet springAcross all locations, no difference
9 Theory behind AVAIL: Promotional Claims Negatively charged organic co-polymerNOT a slow release product or nutritional productMaleic and itaconic acidsIncreases negative charge around fertilizer, essentially attempts to increase CECReduces formation ofinsoluble P – Al, Ca,Fe complexesEnough to make a difference?
10 Properties of Maleic and Itaconic Acids Maleic AcidOrganic compoundTwo carboxyl groupsSoluble in waterSimilar to organic acids that are pumped out of rootsItaconic AcidOrganic compoundFormed from the distillation of citric acidUsed in plasticsThere is no published information on the mode of action for Maleic-Itaconic copolymer in soil or in agricultural applications
11 Phosphorus Fertilizer Trials: 2007-2009 Two studies with different design, each evaluating similar response variables.ObjectivesDetermine whether starter P fertilizer is useful on soils with STP of medium, high, or very high (PI>25)Evaluate the use of starter P fertilizer, with and without Avail fertilizer enhancer, on early season plant color and height, plant nutrient uptake, stover/silage yield, and grain yield.
12 Soil Interpretation Indexes Response0-10Very LowHigh11-25Low26-50MediumMedium/Low51-100None/Low100+Very HighNonePI * 1.2 = ppm M-3 PPI * 2.1 ~ lb P/ac to 8”
13 Experiment One: 2007 & 2008Medium Soil Test P (25-50 PI), High Soil Test P ( PI), and Very High Soil Test P (> 100)Locations: Waynesville (CT), Salisbury (NT), and Fletcher (CT)TreatmentsStarter 30 lb N ac-1Starter 30 lb N ac-1 and 30 lb P205 ac-1Starter 30 lb N ac-1 and 30 lb P205 ac-1 + AvailN source: ; P source:N added to all treatments at V6 for a total of 200 lb N ac-1P applied in 4” band over the rowRCBD, 4 ReplicationsHow was N applied?
14 Experiment One: 2007 & 2008 4-row plots, 25’ or 30’ long Plant height determined ~3 weeks after emergenceRelative color also determined, scaled 0 (dark green) to 3 (yellow or purple)Corn grain yield from center 2 rows of each plot (20’ total), corrected to 15.5% moistureTissue and grain samples at harvest for N and P analysisHow was N applied?
15 Corn Yield 2007 & 2008: Fletcher High Soil Test Phosphorus
16 Corn Yield 2007 & 2008: Salisbury High Soil Test Phosphorus
17 Corn Yield 2007 & 2008: Waynesville High Soil Test Phosphorus
18 Corn Yield 2008: Waynesville Medium Soil Test Phosphorus One year only
19 Corn Yield 2007 & 2008: Salisbury Medium Soil Test Phosphorus
20 Corn Yield 2008: Fletcher Low Soil Test Phosphorus
21 Trial 1 Conclusions: Starter Phosphorus Fertilizer Yields similar across STP levelsNo treatment affect on grain or silage yieldNo treatment affect on grain N or PFor mineral soils, starter phosphorus fertilizer is not necessary for corn when soil test P is high or very highFor piedmont and mountain soils, starter phosphorus fertilizer may not be necessary for corn when soil test P is mediumNo advantage to Avail fertilizer enhancer on any measured variables
22 Experiment Two: 2008 & 2009 P Rate Trial Medium Soil Test P (25-50 PI)Location: FletcherP recommendation: 70 lb P205 ac-1Starter Fertilizers39 lb N ac-1 N39 lb N ac-1 N + 25, 50, 75, 100, 125 lb P205 ac-139 lb N ac-1 N + Avail + 25, 50, 75, 100, 125 lb P205 ac-1Starter surface banded 2” to side of seed furrowN source: 30%UAN; P source:N added to all treatments at V6 for a total of 230 lb N ac-1
23 Experiment Two: 2008 & 2009 P Rate Trial RCBD, 4 or 5 replications4-row plots, 30’ longPlant height determined ~3 weeks after emergenceRelative color also determined, scaled 0 (dark green) to 3 (yellow or purple)Corn grain yield from center 2 rows of each plot (20’ total), corrected to 15.5% moistureTissue and grain samples at harvest for N and P analysisHow was N applied?
24 Plant Color at V6 Rating Color Dark green 1 Green 2 Light green 3 Dark green1Green2Light green3Yellow/purple
29 Trial 2 Conclusions: Starter Phosphorus Rate and Avail No treatment affect on grain yield or stoverNo treatment affect on grain or stover N or PEarly season differences in color and height (2009) did not translate into yield differencesFor CT mountain soilsStarter P fertilizer may not be necessary for corn when soil test P is mediumNo advantage to Avail fertilizer enhancer, regardless of rate, on any measured variables
30 Take Home MessageStarter P not likely to result in positive yield response for corn grown in mineral soils with STP medium or aboveAvail fertilizer enhancer did not improve yields or P uptake by corn on medium STP soils
31 Acknowledgements Wesley Childres, Soil Science Randy Weisz, Crop ScienceRon Heiniger, Crop ScienceDan Israel, Soil ScienceAgriumCorn Growers Association of North CarolinaNorth Carolina Small Grain Growers AssociationNCDENR – USEPA 319 fundsSouthern StatesYara
32 Participants in Starter P Study Mike Carroll – CravenJosh Gady - DuplinKeith Wood - CherokeeArt Bradley – EdgecombeLouie Johnson – GreeneMark Keene – LenoirJosh Beam – LincolnBryant Spivey – OnslowBen Knox – UnionKevin Johnson – WayneNorman Harrell - WilsonProducers who helped!Sheri Cahill – NCSU, SoilsAmy Johnson – U. TennDavid Hardy – NCDA&CSGaylon Ambrose – Beaufort/HydeAnthony Cole – Buncombe, Alleghany, Rowan, HendersonSeth Nagy/Lynn Howard – CaldwellMark Powell – CamdenC. Mike Williams – ChowanAl Wood – PasquotankMany field agents across North Carolina helped with these trials, as did some NCDA&CS staff. We greatly appreciate those farmers who worked with us.
41 Fundamental IssuesFertilizer cost, limited product availability at local levelConsequently, many growers have reduced or eliminated fertilizer inputs….impact on longer term effects???Growers looking for alternatives - renewed industry push of ‘specialty’ fertilizers and products“Green” movement: public perception and environmental issues at the forefrontBuy local! Produce quality vs. quantity
42 Conclusions: Starter Phosphorus Fertilizer For mineral soils, starter phosphorus fertilizer is not necessary for corn when soil test P is high or very highFor piedmont and mountain soils, starter phosphorus fertilizer may not be necessary for corn when soil test P is mediumStarter phosphorus still needed for organic or mineral organic soils for low, medium and high soil test P
43 Corn Grain Yields: Fletcher This is pooled data-both years25 lb best, avg stp 4012000 = 192 bu/ac13000 = 208 bu/ac
44 Corn Yields Grain: Fletcher This is 2008 data25 lb best, avg stp 40