Advanced Nitrogen Management with Cover Crops. Charlie White Kristy Borrelli Jeff Graybill

Transcription

1 Advanced Nitrogen Management with Cover Crops Charlie White Kristy Borrelli Jeff Graybill

2 Managing nitrogen in our cropping systems is complicated NH 3 NH 3 NH 3 NO 3 NO NH NO NO 3 NO 3 3 NO 3 NO3 NO 3 NO 3 NO 3 NO 3 NO 3 NO 3 Fall > Winter > Spring > Summer Basic nitrogen management doesn t cut it!

3 Soil Management Nitrogen management with cover crops is influenced by many factors Soil Organic Matter Fall Soil NO 3 N + + N Supply to Corn Winter Nitrate Leaching + Cover Crop Growing Degree Days Cover Crop Biomass C:N Cover Crop Biomass Spring N NonLegume Seeding Rate + + Cover Crop Management White et al., Managing the tradeoff between nitrogen supply and retention with cover crop mixtures. Agriculture, Ecosystems, and Environment 237:

4 Online decision support tool to assess N tradeoffs and cover crop management White et al., Managing the tradeoff between nitrogen supply and retention with cover crop mixtures. Agriculture, Ecosystems, and Environment 237:

5 Testing the decision support tool in onfarm demonstration plots Lancaster County Demonstrations Hursh Farm Fall manure application Harvest cover crop for forage 3,000 gal/ac spring manure application (342137) Sidedress nitrogen on corn grain Zimmerman Farm Fall manure application Return cover crop residues to soil No spring manure Sidedress nitrogen on corn silage

6 Step 1: Soil sample in fall before cover crop planting to measure soil organic matter and nitrate concentrations Hursh Zimmerman Soil Nitrate 20 ppm 20 ppm Organic Matter 3.7% 4.6% Step 2: Estimate fall and spring growing degree days from cover crop planting to spring termination Planting: September 15 Termination: April 15 Hursh Zimmerman Fall GDD (Base 32 o F) Spring GDD (Base 32 o F) (using temperature data from

7 Pure Legume Pure Grass Step 3: Plug values into the calculator and evaluate the graphical output Hursh Farm

8 70% NonLegume Rate 70% NonLegume Rate Step 4: Choose a nonlegume seeding rate for the cover crop mixture Hursh Farm Zimmerman Farm Final Mix 7 lbs/ac annual ryegrass (35% of monoculture rate) 42 lbs/ac wheat (35% of monoculture rate) 6 lbs/ac crimson clover (30% of monoculture rate) Final Mix 14 lbs/ac annual ryegrass (70% of monoculture rate) 6 lbs/ac crimson clover (30% of monoculture rate)

9 Step 5: In spring Measure cover crop biomass N at termination Greenseeker handheld NDVI meter 110 lbs/ac N in cover crop biomass Zimmerman Farm 0.82 NDVI

10 Step 5: In spring Measure cover crop biomass N at termination Update model with actual fall and spring GDD accumulations Hursh Fall GDD (Base 32 o F) Spring GDD (Base 32 o F) Zimmerman Predict a relative corn yield without fertilizer applied Hursh Farm Zimmerman Farm

11 Step 6: Calculate a supplemental N fertilizer rate General formula is: Fertilizer N rate = Yield deficit x N requirement/yield unit Yield deficit = Yield potential x (1 Relative yield) N requirement = 1.2 lbs N/bu or 9 lbs N/T Hursh Farm Yield Potential = 275 bu/ac Yield Deficit = 275 x (1 0.76) = 66 bu/ac Fertilizer N Rate = 66 bu/ac x 1.2 lbs N/bu = 79 lbs N/ac Zimmerman Farm Yield Potential = 21 T/ac Yield Deficit = 21 x (1 0.95) = 1.1 T/ac Fertilizer N Rate = 1.1 T/ac x 9 lbs N/T = 10 lbs N/ac Spring manure credit is 33 lbs N/ac Final fertilizer requirement = = 46 lbs N/ac

12 Results of Corn Response to N Fertilizer Rates N Rate lbs N/a Hursh Farm Yield b a * a p > Zimmerman Farm N Rate Yield lbs N/a t/a a * a a p > *Model Predicted N Fertilizer Requirement

13 LateSeason Stalk Nitrate Results N Rate Hursh Farm Stalk Nitrate Category lbs N/a ppm Low Excessive * Excessive N Rate Zimmerman Farm Stalk Nitrate Category lbs N/a ppm 0 * Low Excessive Excessive Optimal lateseason stalk NO 3 N is 700 to 2,000 ppm *Model Predicted N Fertilizer Requirement

14 Thank You! For more details contact: Charlie White Funding for this work was provided by: Northeast SARE Pennsylvania State Program Cover Crop Innovations: A Training Program for Agricultural Service Providers USDANIFA Organic Research and Extension Initiative Finding the Right Mix: Multifunctional cover crop cocktails for organic systems

15 Forage Quality Hursh Farm Cover Crop Mix NIR Moisture 80.4 NIR Dry Matter 19.6 Crude Protein 17.0 %DM ADF Protein 0.88 % DM NDF Protein 5.06 % DM ADF Fiber 26.9 % DM andf 51.1 % DM Lignin 2.51 % DM

16 Forage Quality Zimmerman Farm Fresh Ryegrass/Clover NIR Moisture 86.7 NIR Dry Matter 13.3 Crude Protein 18.2 %DM ADF Protein 0.94 % DM NDF Protein 2.74 % DM ADF Fiber 24.9 % DM andf 37.1 % DM Lignin 2.91 % DM

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