Most of the phosphorus in agricultural runoff is associated with organic matter (plant residues or manure) or the soil particles. If the amount of sediment or organic matter reaching surface waters is reduced, the amount of phosphorus will also be reduced.
Different agricultural practices can be used to reduce the amount of phosphorus that is being land-applied as manure so that the risk of water pollution is minimized. According to the University of Tennessee Agricultural Extension Service, here are five best management practices (BMPs) for phosphorus management:
- Manipulation of animal and poultry diets to reduce the amount of phosphorus excreted in manure.
- Physical or chemical treatment of manure treatment to separate some of the phosphorus from the manure or change the chemistry of the manure.
- Application of manure based on crop nutrient requirements, using methods that reduce the risk of runoff to surface waters.
- Effective soil erosion control practices on application sites including no-till agriculture, contour tillage, leaving crop residues on the soil surface after harvest and growing winter cover crops.
- Use of vegetative buffer strips along stream and river banks to slow down run-off, capture sediments and increase infiltration and phosphorus uptake rates.