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North Central Region One Water Action Forum

- 1. Nutrient Management Challenge of Reducing Field P Contribution Greg LaBarge, Field Specialist Agronomic Systems Great Lakes Big Rivers Conference-December 2018
- 2. The Challenge • Scale • Spatial – Landscape extent of small parcels • Field Level P Contribution • Economics • Implementation cost per pound P reduction
- 3. Units Category Value Parcel count (number) 126,919 Acres 5,513,628 Average Parcel size (Acres) 43.4 Acres
- 4. Units Category Value Parcel count (number) 126,919 Acres 5,513,628 Average Parcel size (Acres) 43.4 Acres P Type Target Total P 860 MT DRP portion 186 MT DRP 0.05 PPM
- 5. What Determines Loss Potential in a Field? Source + Transport = Loss • Soil Test Level (P) • Nutrient additions • Soil Type • Drainage • Management • Cover • Distance to water • Pounds of loss per acre Tools • For P, P Risk Index • For soil erosion, RUSLE 2
- 6. Edge of Field-EOF 20 sites with paired fields total of 40 fields being sampled for edge of field losses of nutrient Monitoring both: • Surface • Subsurface water (Tile) USDA-ARS-Dr Kevin King
- 7. Water Flow on Acre of Ground in WLEB Surface Discharge 8% Tile Discharge 25% Soil Retained 68% Annual Water Flows Average of 6 Silty Clay Loam field sites in NW Ohio 2015-2017 Water Years Average Rainfall 35.1 inches Source Inches Percentage Surface Discharge 2.8 8% Tile Discharge 8.6 25% Total Discharge 11.4 32% Soil Retained 23.7 68% Total 35.1 100% Source: USDA-ARS Silty Clay Loam Soil Water Holding Capacity (NRCS) 6.9 inches to 60 inches deep
- 9. Discharge from a 40 Acre Field Source Inches Annual ft3 from 40 Acre Equivalent Olympic Size Swimming Pools Surface Discharge 2.8 8% 406,583 5 Tile Discharge 8.6 25% 1,248,793 14 Total Discharge 11.4 32% 1,655,376 19
- 10. Water Flows in Maumee River River Flow Minutes out of year 1,000 CFS 28 10,000 CFS 3 Time period for annual discharge from 40 acre field to flow past gauge station
- 11. Field Level DRP Concentrations < DRP Concentration: Subsurface < Surface Filtering through results in lower P concentrations Source: USDA-ARS
- 12. Field Level DRP Loading > 3 times Water Volume Subsurface vs Subsurface DRP Loading: Subsurface > Surface Source: USDA-ARS
- 13. Annual P Loading from a 40 Acre Field at (0.25 pound/Acre loss) Source Water (ft3) DRP Load (lbs) Surface Discharge 405,977 2.1 Tile Discharge 1,251,487 7.8 Total Discharge 1,657,464 9.9
- 14. Soil Test?
- 15. Influence of Soil Test P on Field P Losses King et al., 2018 Duncan et al., 2017
- 16. Influence of Soil Test P on Field P Losses Soil Test P above agronomic rates increases environmental risk King et al., 2018 Duncan et al., 2017
- 17. Influence of Soil Test P on Field P Losses Soil Test P above agronomic rates increases environmental risk BUT Soil Test P does not equal environmental risk King et al., 2018 Duncan et al., 2017
- 21. P Index (and Other Tools) Category Value Parcel count (number) 126,919
- 22. P Index Calculations for 77 Farms (38,186 Acres) in WLEB Estimated P loss (lbs. per acre) * Loss with nutrient applications Percent Acres 0-0.5 20% >0.5-1.5 52% >1.5-2.5 20% >2.5-5.0 8% >5.0-10.0 0% *Calculated through Annual Phosphorus Loss Estimator (APLE) Tool
- 23. P Index Calculations for 77 Farms (38,186 Acres) in WLEB Estimated P loss (lbs. per acre) * Sediment P Loss Percent Acres Dissolved P Loss Percent Acres Loss with nutrient applications Percent Acres 0-0.5 51% 74% 20% >0.5-1.5 38% 25% 52% >1.5-2.5 7% 1% 20% >2.5-5.0 2% 0% 8% >5.0-10.0 2% 0% 0%
- 24. Cost per Pound of P Reduction on 40 Acre Field (0.25 pound/Acre loss) BMP Practice Predicated Reduction Effectiveness Original DRP Load (lbs) Reduction (lbs) Total Cost to Implement Cost per lb of P reduction BMP 1 40% 9.9 4.0 $1120 $281
- 25. Cost per Pound of P Reduction on 40 Acre Field (0.25 pound/Acre loss) BMP Practice Predicated Reduction Effectiveness Original DRP Load (lbs) Reduction (lbs) Total Cost to Implement Cost per lb of P reduction BMP 1 40% 9.9 4.0 $1120 $281 BMP 2 58% 9.9 5.7 $1120 $196
- 26. Cost per Pound of P Reduction on 40 Acre Field (0.25 pound/Acre loss) BMP Practice Predicated Reduction Effectiveness Original DRP Load (lbs) Reduction (lbs) Total Cost to Implement Cost per lb of P reduction BMP 1 40% 9.9 4.0 $1120 $281 BMP 2 58% 9.9 5.7 $1120 $196 BMP 3 95% 9.9 9.4 $6500 $691
- 27. Cost per Pound of P Reduction on 40 Acre Field (1.5 pound/Acre loss) BMP Practice Predicated Reduction Effectiveness Original DRP Load (lbs) Reduction (lbs) Total Cost to Implement Cost per lb of P reduction BMP 1 40% 60 24.0 $1120 $47
- 28. Cost per Pound of P Reduction on 40 Acre Field (1.5 pound/Acre loss) BMP Practice Predicated Reduction Effectiveness Original DRP Load (lbs) Reduction (lbs) Total Cost to Implement Cost per lb of P reduction BMP 1 40% 60 24.0 $1120 $47 BMP 2 58% 60 34.8 $1120 $32
- 29. Cost per Pound of P Reduction on 40 Acre Field (1.5 pound/Acre loss) BMP Practice Predicated Reduction Effectiveness Original DRP Load (lbs) Reduction (lbs) Total Cost to Implement Cost per lb of P reduction BMP 1 40% 60 24.0 $1120 $47 BMP 2 58% 60 34.8 $1120 $32 BMP 3 95% 60 57.0 $6500 $114
- 30. Cost per Pound of P Reduction on 40 Acre Field BMP Practice Predicated Reduction Effectiveness Total Cost to Implement 0.25 lb/A loss Cost per lb of P reduction 1.5 lb/A loss Cost per lb of P reduction BMP 1 40% $1120 $281 $47 BMP 2 58% $1120 $196 $32 BMP 3 95% $6500 $691 $114
- 31. The Challenge-Summary • Scale • Spatial-large geographic region • Field Level P Contribution-Generally small Contributions • Economics • Implementation cost per pound P reduction-Need to target conservation practices to improve ROI