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Environmental Needs for In-Season N Management. S.B. Phillips Virginia Tech. 337.5. 284.8. 183.2. Nutrient Inputs into the Chesapeake Bay. 400. 30. 27.13. 350. 25. 300. 19.12. 20. 250. Million lb N/Year. 12.8. 200. 15. Million lb P 2 O 5 /Year. 150. 10. 100. 5. 50. 0. 0.
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Environmental Needs for In-Season N Management S.B. Phillips Virginia Tech
337.5 284.8 183.2 Nutrient Inputs into the Chesapeake Bay 400 30 27.13 350 25 300 19.12 20 250 Million lb N/Year 12.8 200 15 Million lb P2O5/Year 150 10 100 5 50 0 0 1985 2000 2010
Phosphorus Input into the Chesapeake Bay (millions of pounds/year)
VA Poultry Industry: Total Manure Production ~ 560,000 tons/year. N = 34.7 Million lbs; Phosphate = 35.0 Million lbs Shenandoah Valley 453,000 tons Eastern Shore 31,000 tons Southeast 7,400 tons South Central 48,500 tons Counties with 4-20 houses
Phosphorus applied as poultry litter (4t/A) versus crop removal PL Corn-GRN-130 Added Removal Pasture Hay-3t Alfalfa-4t Rye-SLG-6t Corn-SLG-17t CS/RS 0 50 100 150 200 250 lbs P2O5/acre
Delmarva Legislative Action Phosphorus - Based Nutrient Management Plans
Nutrient Management Legislation Maryland: Water Qual. Imp. Act, 1998 NMP - 8 AU P-Based – Chemical Fertilizer 12/31/02 P-Based – Manure/Biosolids 7/01/04 Delaware: Delaware Nutrient Mgmt. Law, 1999 NMP - 8 AU or owns/leases/controls - 10 ac P-Based – P appl. to high P soils cannot exceed 3-yr crop removal rate Virginia: Poultry Waste Mgmt. Act, 1999 NMP – 200 AU P-Based – 10/01/01 P rates – not exceed crop needs or crop removal
Soil Test P - Eastern Shore of VA HIGH MEDIUM 29.1 % 3.4 % • Applying 31,000 Tons of Litter • to Produce 150 bu/acre Corn: • N-Based - 7,440 acres required • P-Based - 37,000 acres required VERY HIGH 67.5 %
Nitrogen Based Rate = 4.2 t/A 150 lb PAN/A 260 lb P2O5/A 122 lb K2O/A Land required = 36 A N needs met 240 lb P2O5/A Surplus 82 lb K2O/A Surplus Phosphorus Based Rate = 0.97 t/A 35 lb PAN/A 60 lb P2O5/A 28 lb K2O/A Land required = 181 A 115 lb N/A Deficit P2O5 needs met 12 lb K2O/A Deficit Poultry litter from 20000 broilers applied to 150 bu/acre corn crop
In-Season N Fertilization • Increased cost to growers • Need to maximize efficiency NOT A PUTTING GREEN! Improved Varieties Reduced Tillage Systems Accurate Rate Determination Optimize Application Timing Management of Spatial Variability