CRP improves water quality. Water quality benefits accrue in multiple ways. CRP reduces the nitrogen and phosphorus leaving a field in runoff and percolate. Grass filters and riparian buffers (partial field enrollments) intercept sediment, nutrients, and other contaminants before they enter waterways. Wetlands restored and constructed by CRP improve water quality by converting nitrate / nitrogen into benign atmospheric nitrogen. Additionally, the CRP provides hydrologic storage, attenuates flood waters, and helps recharge aquifers.
The cost effectiveness of wetlands designed and sited for nitrate removal: The effect of increased efficiency, rising easement costs and lower interest rates, Skip Hyberg, Rich Iovanna, William Crumpton, and Shawn Richmond (2015) (PDF)