From No-Till Farmer online, an article about the reduction of nutrients in Chesapeake Bay with conservation ag practices. Note, at the bottom, the finding about cover crop adoption being able to make significant additional contributions.
USDA-NRCS released an assessment of the effects of conservation practices on cultivated cropland in the Chesapeake Bay Region.
The findings of the report were encouraging – with cash incentives, farmers volunteered to protect nearly half of cropland acres with buffers or terraces, while no-tillage was used on 48% and reduced tillage on 40% of cropland.
The adoption of conservation practices resulted in 55% reduction in edge-of field sediment loss, 42% reduction in surface nitrogen losses, 31% reduction of subsurface losses of nitrogen, and 41% reduction in phosphorus losses (both sediment-bound and soluble).
Implementation of the BMPs reduced total loads from all sources (including urban, hay and pasture, urban land) delivered to the Chesapeake Bay by 10% for sediment, 14% for phosphorus and 14% for nitrogen.
The report also recognized there was potential for further improvement, especially on 19% of cropland which was in need of further conservation treatment. The report recommended targeting these areas of highest need, and to help land users implement comprehensive conservation plans which cover soil erosion control and comprehensive nutrient management (including rate, form, timing and method of nutrient application).
The report estimated that only 4% of cropped acres used cover crops in the period of assessment (2003-06). It was estimated that adoption of cover crops on all cropped acres could reduce sediment loss further by 59%, nitrogen loss by 19% (subsurface loss by 31%), and phosphorus loss by 32%.