Effect of nitrogen best management practices on water quality at the watershed scale

Abstract

Coastal marine ecosystems are important for their productivity and because nearly 40% of the world’s population live in close proximity to them. Nutrient overenrichment leading to hypoxia of coastal marine ecosystems is accelerating at an unprecedented rate. This chapter summarizes the effectiveness of various agricultural Best Management Practices (BMPs) to reduce nitrate-N losses from tile drained areas of the Midwestern Corn Belt. These BMPs can be classifi ed into three general categories: hydrologic modifi cation, nutrient management and landscape diversifi cation. Hydrologic modifi cation includes changes in tile drain depth and spacing, and a practice known as controlled drainage. These practices have been shown to reduce nitrate-N losses through tile drains by from 15–96%. Nutrient management includes changes in rate and timing of application for either fertilizer or manure. These practices have been shown to reduce nitrate-N losses through tile drains by from 6–58%. Landscape diversifi cation includes changes in cropping systems, planting of cover crops or riparian buffer strips, agroforestry, prairie restoration or wetland restoration. These practices have been shown to reduce nitrate-N losses by from 5–97%.