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12. Nitrogen Know-how

Review of the latest research on corn nitrogen fertilizer. Specifically covering the long-term impact of nitrogen fertilizer rates on soil health and new technologies to better predict nitrogen fertilizer requirements in corn. Joshua Nasielski, University of Guelph

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12. Nitrogen Know-how

  1. 1. Nitrogen Know-How Joshua Nasielski, Allison Bailey, Caleb Niemeyer, Ken Janovicek, Bill Deen (with data from Scott Banks)
  2. 2. When do we think the frog is deaf… …when discussing MERN
  3. 3. University of Minnesota, Institute on the Environment Fertilizer Environmental Performance Benchmarks (USA, Europe) • N Balance (N applied – N removed in grain) • 50-70 kg N ha-1 • N surplus (N applied – N uptake) • 50 kg N ha-1 When MERN is applied, all benchmarks are met or exceeded (8-year study at Elora, ON) (Nasielski et al. 2020)
  4. 4. • Elora, ON (silt loam) • Starting SOM = ~4.0% • Continuous corn • Typical seeding rate, tillage, variety, etc. • 6 long-term N rates: • (30, 58, 87, 145, 208, 260 kg-N ha-1) After 10 years, what happens to soil health? (Allison Bailey, M.Sc student) Effect of N rates on soil organic matter (10-year study; 2009-2018)
  5. 5. Effect of long-term N rate on soil organic carbon (2009-2018) (Allison Bailey, M.Sc research) 30 58 87 145 207 260 Applied N (kg N ha-1) Percent change in SOM (top 20cm) -7% -2% -5% +4% +6% +9% Trend is clear! MERN
  6. 6. Optimal N rate range is 140-260 kg N/ha! (same soil, same management, same hybrid!) Year-to-year variation in MERN within a field (2009-2018)
  7. 7. Spatial variation in MERN (2019 Eastern Ontario) (Holly Byker and Scott Banks) • Winchester: 108 lbs N ac-1 • Morrisburg: 123 lbs N ac-1 • North Gower: 148 lbs N ac-1
  8. 8. 6 – Field Factors Soil Health Soil Drainage Water Holding Capacity 1 – Plant Factors Yield Expectation Plant Tissue N Status NDVI 2 – Weather Factors Rainfall Temperature Crop Heat Units 3 – Cropping System Factors Previous Crop Tillage System Manure Additions 4 – Soil Factors Soil Texture Soil Organic Matter Soil N mineralization 5 – Nitrogen Factors Price of Corn / Nitrogen Source of Nitrogen Application Method/Timing Source: Bill Deen, U of G Why does MERN vary?
  9. 9. Measuring MERN the ‘easy’ way: Delta-Yield (Ken Janovicek and Bill Deen) 0 50 100 150 200 250 0 50 100 150 200 250 Yield(bu/ac) Applied N (lbs N/ac) Delta-Yield
  10. 10. Estimating MERN with Delta-Yield (2019) (Scott Banks) 123 lbs N ac-1 110 lbs N ac-1 155 lbs N ac-1 • Winchester: 108 lbs N ac-1 • Morrisburg: 123 lbs N ac-1 • North Gower: 148 lbs N ac-1
  11. 11. The Delta-Yield Calculator (Ken Janovicek and Bill Deen) • Calibrated using hundreds of Ontario trials, majority on-farm. • Works pretty well and is being improved 0 50 100 150 200 250 -1 1 3 5 7 9 EconomicNRate(kg-N/ha) Delta yield (Mg/ha) N-Rate vs Delta Yield - Calibration Green… Yellow… Red…
  12. 12. Predicting MERN in-season: how early can it be done via precision agriculture?
  13. 13. Value of estimating MERN: How accurate do we need to be in N rate estimation to reduce economic risk? +/- 30 kg N /ha generally gets within $10/ac of max profit
  14. 14. Our Hypothesis: Rain makes corn Can we use in-season rainfall to predict yield and MERN? Did not look at fields with manure or red clover
  15. 15. When does rain make corn? Evidence from Elora N rate trial (2009-2018) (Caleb Niemeyer M.Sc thesis, 2019) Correlation between rainfall during V5 to V12 (approx. June 15 to July 15) Corn Yield Optimum N rate Rainfall 0.90 0.66 Simple equation using recommended rate (OCNC; gocorn.net) as base: • Add ~1 lb N/ac every 1 mm of rainfall between V5-V12
  16. 16. Does the rainfall and MERN relationship hold? (Caleb Niemeyer M.Sc thesis, 2019) • 22 site-years at Elora • 27 site-years at Ridgetown • All rotations represented • Not including red clover • No manure • All loam soils (clay to sandy) With rainfall adjustment, profit increased by average of $20/ac over normal OCNC prediction. With rainfall adjustment, the predictive capacity of the OCNC to estimate actual MERN doubled. (R2 increase from 0.19 to 0.48)
  17. 17. 0 2 4 6 8 10 12 14 16 18 20 -40 to -15 -15 to 0 1 to 20 21 to 40 41 to 60 61 to 80 81 to 100 101 to 120 Frequency Increase in fertilizer return ($/ac) with rainfall adjustment 40% of cases lost money (average loss of -$10/ac) 30% of cases made some money (+$18/ac) 30% of cases made a lot of money (+$75/ac) Frequency distribution of profit response (n=49) (Caleb Niemeyer M.Sc thesis (2019)
  18. 18. Will corn respond to a delayed application of fertilizer N?
  19. 19. • Elora, 2017, silt loam • 3.4% SOM • Image at silking, July 26
  20. 20. • Same image but with NDVI • Red areas = N stress
  21. 21. • Elora, 2017, silt loam • Image at silking, July 26 • N applied July 15 (V12) • 230 lbs N/ac • 10 mm rainfall (July 15-26)
  22. 22. Does N respond to N applied at V12? (Elora, 2017) N treatment Grain Yield (bu/ac) (+/- SE) No N at all 109 (± 7) 230 lbs N ac-1 all at V12 202 (± 14) 230 lbs N ac-1 all pre- plant 211 (± 6) +100 bushel gain - 9 bushel penalty
  23. 23. Split Nitrogen Rates MSCIASpponFeed Nitrogen Sulfur Trial MSCIABoronTrial UreaInjuryTrial 2018 Bornholm Ben Rosser’s research
  24. 24. N treatment Grain Yield (bu/ac) (+/- SE) No N at all 122 (± 7) 175 lbs N ac-1 all at V13 174 (± 10) 175 lbs N ac-1 all pre-plant 172(± 9) +52 bushel gain + 2 bushel gain Ben Rosser research at Bornholm (2018)
  25. 25. Potential kernel number Components of yield potential Potential kernel weight Getty Images Canopy size
  26. 26. Late N applications: evidence of efficacy (Fernandez et al. 2019; Mueller et al. 2017; Nasielski et al. 2019; Nasielski et al. 2020) • Split-N generally does not increase or decrease yield relative to pre-plant applications. • Exception on sandy soils or very wet springs • Split-applying N provides small increase in N recovery efficiency (~5%) • Benefit of late N is to identify and react to extreme years when MERN is high • Unknown how 4R management influences efficacy of late N • Impact of rainfall?
  27. 27. • 3 locations • 4 N rates pre-plant (lbs N ac-1): • 0, 66, 133, 200 • 2 split-N strategies to account for June 15 to July 15 rainfall: • 100 lbs N/ac pre-plant + 1 lbs N per 3 mm • 100 lbs N/ac pre-plant + 1 lbs N per 1 mm • June 15-July 15 rainfall (60mm) is close to 10- year average (68mm). Rainfall adjustments in eastern Ontario (2019) – Scott Banks with farmer-cooperators
  28. 28. 0 20 40 60 80 100 120 140 160 180 200 0 50 100 150 200 250 Yield(buac-1) Applied N (lbs N ac-1) North Gower Field 2019 Actual MERN = 148 lbs N ac-1 Strategy #1 MERN = 130 lbs N ac-1 Producer MERN = 137 lbs N ac-1 Strategy #2 MERN = 160 lbs N ac-1
  29. 29. 0 50 100 150 200 250 300 0 50 100 150 200 250 Yield(buac-1) Applied N (lbs N ac-1) Winchester Field 2019 Actual MERN = 110 lbs N ac-1 Strategy #1 MERN = 130 lbs N ac-1 Producer MERN = 130 lbs N ac-1 Strategy #2 MERN = 150 lbs N ac-1
  30. 30. • Normally 200+ bu/ac field, but late planting this year (May 22) Morrisburg Field 2019 0 40 80 120 160 200 0 50 100 150 200 Yield(buac-1) Applied N (lbs N ac-1) Actual MERN = 116 lbs N ac-1 Strategy #2 MERN = 120 lbs N ac-1 Producer MERN = 90-100 lbs N ac-1 Strategy #2 MERN = 160 lbs N ac-1
  31. 31. Economics of N application Morrisburg Field (2019) Per acre return to N fertilizer ($ corn – $ fertilizer) Actual MERN 573 Farmer Estimate 561 Strategy #1 Late N 572 Strategy #2 Late N 547 Assume corn @ $180/ton and N @ 50cents/lb Within $12/ac Not a high-yielding year. Would not expect major profit increase from rainfall adjustment
  32. 32. Take Home #1 • MERN: • Increases soil organic matter (over time) • Meets or exceeds benchmarks of environmental performance • Is profitable (duh!)
  33. 33. Take Home #2 • MERN varies from field-to-field, year- to-year • Delta-Yield let’s you understand how MERN varies on YOUR farm
  34. 34. Take Home #3 • In 8 out of 10 years, a properly calibrated N rate will get you within $10-15 ac-1 of MERN. • It is the 2 out of 10 years where MERN is very different that you need to pay attention too.
  35. 35. Take Home #4 • Mid-season rainfall adjustments can identify extreme years. • We are updating our simple rainfall adjustment algorithm using Bayesian networks and precision ag. (led by John Sulik)
  36. 36. Thank you. Questions? For help in MERN calculations using Delta-Yield: nasielski@uoguelph.ca neoag.uoguelph.ca

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