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Delaware Nutrient Load Reductions for Agricultural BMPs

Delaware Nutrient Load Reductions for Agricultural BMPs. Chesapeake Bay Program Tributary Strategy Workgroup Meeting November 7, 2006. Why are we here?. A brief overview of BMPs that are quantified in Delaware Present water control structure overview and Nitrogen reduction data

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Delaware Nutrient Load Reductions for Agricultural BMPs

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  1. Delaware Nutrient Load Reductions for Agricultural BMPs Chesapeake Bay Program Tributary Strategy Workgroup Meeting November 7, 2006

  2. Why are we here? • A brief overview of BMPs that are quantified in Delaware • Present water control structure overview and Nitrogen reduction data • Request that the CBP account for water control structure reductions

  3. Chesapeake Bay Watershed New York Pennsylvania Maryland Delaware West Virginia District of Columbia Virginia

  4. Over 90% of the Bay and its tidal rivers are impaired due to low dissolved oxygen levels and poor water clarity, all related to nutrient and sediment pollution. Without oxygen and grasses, the Bay’s crabs, oysters, and fish cannot survive and thrive. Impaired Water

  5. Delaware -Total Maximum Daily Load and the Inland Bays Watershed • Promulgated in December 1998 • Removal of all point sources of nutrient loading • Removal of 40-80% of nonpoint N • Removal of 40-65% of nonpoint P • Implementation through a Pollution Control Strategy Low reduction area High reduction area TMDL developing

  6. PCS Workgroup • Members from various agencies • DNMC • DNREC: DWR & DSWC • NRCS • Sussex Conservation District • Kent Conservation District • University of Delaware Cooperative Extension • Mission: To devise a method to estimate how existing agricultural practices have already contributed to achieving the TMDL mandated nutrient load reductions …

  7. PCS Workgroup Decisions • Calculations/recommendations based on best available science • Averages from several studies and/or ranges • Dependent on weather and site specific conditions • A lag time likely exists between practice implementation and benefit observation • Decisions assist in policy development and incentive based programs

  8. Cropland Loading Rates • Averaged data from two local studies • Ritter (1986) • TN: 20.0 lbs/acre/yr • TP: 0.8 lbs/acre/yr • Ward (2001) • TN: 21.9 lbs/acre/yr • TP: 0.8 lbs/acre/yr • Average loads used • TN: 21.0 lbs/acre/yr • TP: 0.8 lbs/acre/yr

  9. Agricultural BMPs Considered • Reduced Commercial Fertilizer Application • Cover Crops • Conservation Reserve Program Practices • Conservation Reserve Enhancement Program Practices • Water Control Structures • Poultry Compost and Manure Storage Sheds • Manure Relocation and Alternative Use • Phytase • Nutrient Management Plans

  10. Cropland loading rate (lb/acre/yr) Acres treated by BMP Efficiency (%) Water Control Structures in place • N reduction to stream (lb/yr) = x x • Inland Bays watershed 51 Structures, 1,530 acres treated = 29TN/day, 10,603TN/yr • Nanticoke River watershed 12 Structures, 175 acres treated = 3.3 TN/day, 1,213 TN/yr

  11. Cropland loading rate (lb/acre/yr) Acres treated by BMP Efficiency (%) Water Control Structures • Use the N reduction efficiency of 33% reported by Gilliam and Skaggs (1986) • Currently, there is little research to support a P reduction efficiency for water control structures • N reduction to stream (lb/yr) = x x

  12. Water Control Structures • NRCS Code # 587 • Proper installation and maintenance • N-reduction due to volume flow reduction • Storm events – high base flow • N-reduction due to concentration reduction • P-reduction due to sediment transport reduction

  13. Cover Crops (4,203 acres) CRP (200 acres) Grass Buffers (54 acres) Forest Buffers (92 acres) Wetlands (65 acres) Water Control (55 structures) Manure (10,886 tons) Phytase (43,597 acres) NMPs (9,225 acres) Progress to Date from Agriculture

  14. Stormwater Septic Agriculture Reductions Achieved from BMPs on the Ground 23% 88%

  15. Cover Crops (32,231 acres) CRP (0 acres) Grass Buffers (0 acres) Forest Buffers (4,712 acres) Wetlands (5,263 acres) Water Control (0 structures) Manure (14,032 tons) Phytase (NA) NMPs (41,523 acres) Future Agricultural BMP Goals

  16. Questions & Comments

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