Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Biologically Based Fertilizer Recommendations to Meet Yield Expectations and Preserve Water Quality

618 views

Published on

Published in: Environment
  • Be the first to comment

  • Be the first to like this

Biologically Based Fertilizer Recommendations to Meet Yield Expectations and Preserve Water Quality

  1. 1. Franzluebbers and Stuedemann (2010) Soil Sci. Soc. Am. J. 74:2131-2141 Soil Organic Carbon Sequestration (kg . ha -1 . yr -1 ) 0 200 400 600 800 1000 Total Soil Nitrogen Accumulation (kg . ha -1 . yr -1 ) 0 20 40 60 80 100 TSN = 5.7 + 0.102 (SOC) r 2 = 0.98 Relationship between soil C and N accumulation
  2. 2. Linkage of nitrogen with active carbon Soil microbial activity biologically sequesters N into organic matter
  3. 3. Soil process relationships Franzluebbers et al. (1999) Soil Sci. Soc. Am. J. 64:613-623
  4. 4. Available Nitrogen (kg ha -1 ) Relative Yield (fraction) 0.0 0.2 0.4 0.6 0.8 1.0 Sites with high N availability and low N fertilizer response Goal of enlarging the biologically active N pool without causing N leakage Inorganic nitrogen  Surface soil  Residual in profile Organic nitrogen  Long-term stable  Biologically active Accounting for Available Nitrogen (kg N ha-1) Sites with low N availability and high N fertilizer response Idealized response to nitrogen
  5. 5. Virginia Tech – essential findings Hairy vetch cover crop increased corn yield • more than the N credit it supplied Soil nitrate at V4 was correlated with N uptake of the previous cover crop Mineralizable C (1 and 28 day tests) prior to planting and at V4 was not predictive of unfertilized corn yield at 4 sites Soil nitrate at V4 was correlated with unfertilized corn yield (r = 0.45)
  6. 6. Predicting N supply from cover crops and soil organic matter with ecologically-based models                318.03.8, 10 ):(40.0 1max0084.0 NO NC NN Y whcc whccwhwkcc  where,       ngmineraliziNandtillage-noif0.020, ngmineraliziNandtillageif0.034, ngimmobiliziNandtillageif0.12, wh Step 1: Cover Crop N Supply Model Difference in unfertilized corn yield (Mg/ha) between a cover cropped soil and a bare fallow reference Efficiency of N supply is controlled by tillage and N mineralization vs. immobilization Pre-emptive competition for soil NO3 - reduces N supply Winterkilled and winterhardy species have different N supply regulators N mineralization/ immobilization is controlled by microbial carbon use efficiency and biomass stoichiometry White et al. 2016. A model data-fusion approach for predicting cover crop nitrogen supply to corn. Agronomy Journal. doi:10.2134/agronj2016.05.0288
  7. 7. Predicting N supply from cover crops and soil organic matter with ecologically-based models Best Model (r2=0.67) Unfertilized Corn Yield (Mg/ha) = -3.6 + 3.2*Soil %C + 0.14*% sand + 0.054*% silt + 0.46*Cov.Crop N Credit Model with CO2 Burst (r2=0.60) Unfertilized Corn Yield (Mg/ha) = 2.9 + (0.00017 * CO2Burst2)† + 0.14*% sand + 0.48*Cov.Crop N Credit †Term is only included in tilled soils Step 2: Soil Organic Matter N Supply Model • Calibrated with unfertilized corn yields from 5 cover crop experiments (119 plots) • N supply from cover crop residues was isolated using the previously calibrated cover crop N supply model • Find the best predictors of N supply from soil organic matter • Tested total soil %C, 24hr CO2 burst, soil particle size fractions, tillage vs. no-till in a general linear model stepwise selection process
  8. 8. NC State approach Plant N uptake in semi-controlled greenhouse experiments being explored
  9. 9. Plant N uptake in minor relationship with total organic C Pershing (2016) NC State University MS thesis
  10. 10. Plant N uptake in strong relationship with mineralizable N Pershing (2016) NC State University MS thesis
  11. 11. Plant N uptake in reasonable relationship with the flush of CO2 Pershing (2016) NC State University MS thesis
  12. 12. Field trials to evaluate biological N supply Example of 3 strips fertilized with 0, 69, and 125 kg N ha-1 at sidedress - Corn grain and silage in North Carolina and Virginia
  13. 13. 1 2 3 4 Soil sampling (8 cores from each of 4 replicate locations) Soil analyses Flush of CO2, net nitrogen mineralization Routine soil testing for pH, P, K, other elements (NC Dept Agric) Bulk density, particle size, total C-N, microbial biomass C, inorganic N
  14. 14. 20 gal/acre sidedress 36 gal/acre sidedress No sidedress Nitrogen treatments applied 26 June 2015 (32 rows each)
  15. 15. Yield harvest (18’ row sections at 12 points in each strip) Plant analyses Dry matter yield, stand density, nutrient concentration of forage, including protein, fiber, minerals (Ca, P, S, Mg, Na, K, Cu, Fe, Mn, Zn), ADF, NDF, nitrate (NC Dept Agric)
  16. 16. Collected yield estimates on 21 August 2015
  17. 17. Yield Results Sidedress N Application (lb N/acre) 0 40 80 120 Corn Silage Yield (ton/acre) [35% DM] 0 10 20 30 40 Rep 1
  18. 18. Yield Results Sidedress N Application (lb N/acre) 0 40 80 120 Corn Silage Yield (ton/acre) [35% DM] 0 10 20 30 40 Rep 2
  19. 19. Yield Results Sidedress N Application (lb N/acre) 0 40 80 120 Corn Silage Yield (ton/acre) [35% DM] 0 10 20 30 40 Rep 3
  20. 20. Yield Results Sidedress N Application (lb N/acre) 0 40 80 120 Corn Silage Yield (ton/acre) [35% DM] 0 10 20 30 40 Rep 4
  21. 21. Yield Results Sidedress N Application (lb N/acre) 0 40 80 120 Corn Silage Yield (ton/acre) [35% DM] 0 10 20 30 40 Overall (n = 12) Average yield = 23.6 ton/acre
  22. 22. Implications Sidedress N Application (lb N/acre) 0 40 80 120 Corn Silage Yield (ton/acre) [35% DM] 0 10 20 30 40 Overall (n = 12)
  23. 23. Wheat grain evaluations in North Carolina
  24. 24. Flush of CO2 following Rewetting of Dried Soil (mg CO2-C kg -1 soil)0-3 days 0 100 200 300 400 500 0.0 0.2 0.4 0.6 0.8 1.0 1.2 Relative Yield Without In-Season Nitrogen Wheat Tall fescue Corn Preliminary results Unpublished data We’re getting excited about the potential!
  25. 25. alan.franzluebbers@ars.usda.gov

×