ScienceDaily (July 26, 2010) — Scientists are exploring ways to reduce non-point pollution from agriculture. A new study finds that using straw residue in conjunction with legume cover crops reduces leaching of nitrogen into waterways, but may lower economic return.
Agriculture is the largest source of nitrogen non-point pollution to waterways in the United States, flowing into streams and rivers via erosion from farmlands, or through leaching of nitrate into groundwater. Once in aquatic systems, excess nitrogen leads to aquatic ecosystem degradation, including oxygen depravation that leads to fish kills and dead zones. If nitrates leach into drinking water supplies, they are a human health concern and have been linked to blue-baby syndrome, various cancers, and birth defects.
Legume cover crops, such as hairy vetch, have been considered as an alternative or supplement to synthetic nitrogen fertilizers that may improve the sustainability of agricultural systems. Such cover crops can contribute substantial amounts of nitrogen to subsequent crops, as well protect soils from erosion and promote overall soil quality. Legumes tend to release nitrogen more slowly than synthetic fertilizers, possibly being more synchronous with crop demand. That does not mean that nitrogen from legumes cannot be lost from the system.
One way to possibly minimize these losses may be to add more carbon to nitrogen-rich residues, such as those of cereal grain crops, during cover crop phase of the cropping systems. read more