Danish efforts to reduce P loss from agriculture to the aquatic environment

1. Danish efforts to reduce P loss from agriculture to the aquatic environment Gitte Rubæk Danish Institute of Agricultural Sciences

2. Imported animal feed P import (1000 tonnes) Mineral fertilizers Waste products P surplus (Kg P ha-1) (Kyllingsbæk, 2005) The P surplus in Danish Agriculture

3. Depth (cm) 1,4 tonnes P ha-1 has accumulated in on agricultural land Agricult. Forest Total P (mg P/kg jord) The P surplus in danish agriculture P overskud (kg P / ha)

4. Geographic distribution of the P surplus P surplus in 2001 (kg ha-1 agricultural land) (Dalgård et al., 2004)

5. Very high spatial variability in P losses from land Critical source area Transport Source område med Areas with a high potential for P transport område Areas with a high content of potentially mobile P højt indhold af med højt flytbart transport - fosfor potentiale

6. P losses in landscape Surface run-off 2 m uncultivated zone (Law enforced) Buffer Zone (P deposition) Soil erosion Leaching and potential loss through drainage system Meadows, occasionally flooded (P deposition) Stream Banks (source) Cultivated land (source area) Stream Drained low-land soil (Source area)

7. P discharge to coastal waters in DK Waste water Industry Fish hatchery Farm contribution Diffuse losses, cropped land (after Rüegg og Østergaard, 2002)

8. P loss from farmland to surface watersin DK - estimates Certainty of estimate: (+) = Incufficient; (+++) = average; (+++++) = high Total P (tonnes year-1) Erosion-related losses 287 - 695 • Water erosion (++) 7 - 35 • Stream bank erosion (++) 275 - 645 • Wind erosion (+) 5 – 15 Drainage related leaching, total 65 - 405 • Leaching from high risk areas (mineral soils) (+) 15 - 90 • Leaching from other areas (mineral) (+++) 20 - 90 • Leaching from lowland organic soils (+) 30 – 225 Groundwater related leaching, total 125 - 210 • Leaching to shallow ground water (++) 80 • Leaching to deeper ground water(++) 45 – 130 Atmospheric deposition (++++) < 5 SUM (without leaching to deep ground water) 440 - 1180 Kronvang & Rubæk, 2005

9. “Experts” conclusions during the preparations for VMPIII A dual strategy combining: • General measures to reduce the P surplus and optimizing P distribution on farmland • Improved feeding (Digestibility, phytase additions, reduced safety margins based on improved knowledge of physiological need) • Targeted measures to reduce P losses from high-risk areas (critical source areas) Poulsen and Rubæk, 2005, DIAS report nr 68

10. The Danish Action Plans (Vand-Miljø-Planer) • VMP-I and VMP-II had focus on: • N emissions from agriculture • P emissions from point sources • The VMPIII addresses: • The P surplus in agriculture • The P losses from farmland • …and N leaching, vulnerable nature, organic farming and a “slurry action plan”

11. The political agreement on P in VMPIII • 50% reduction in the annual P surplus • tax on feed-phosphates • improved utilization of animal feed P • Buffer zones along streams and lakes • volunteer subsidized agreements (MVJ) • 10 meter zones, 50.000 ha • Research and development…..

12. P related research and development in VMPIII • Reducing the P surplus • P utilization in animal husbandry • Slurry treatment - including combustion • “Land management” • A Danish P index • Management of Stream Banks, Buffer zones, Flood plains and low land • Management on farmland • Modeling P effects in estuaries • Cost and benefits of mitigation strategies • A web-based interactive tool for N and P management of watersheds

13. Land management research projects A Danish P index Management on farmland Mapping layers, mapping techniques Interactive web-based tool for nutrient management Management of buffer zones, stream banks, floodplains and lowlands Modeling P effects in estuaries Costs and Benefits of mitigation strategies

14. Silkeborg, 3-7 sep 2007