Submitted to: International Nitrogen Conference
Publication Type: Abstract Only
Publication Acceptance Date: October 15, 2001
Publication Date: N/A
Recent reports from long-term cropping systems studies in the USA have shown that relying on legume forms of N can increase N and C retention and reduce the global warming potential of cropping systems relative to conventional tillage systems that rely on synthetic N fertilizer. Further improving legume cover crop management may provide even greater reductions in N losses from agricultural systems. We are using innovative cover crop management at the USDA-ARS Farming Systems Project in Beltsville, Maryland, a long-term study designed to assess the sustainability of cropping systems appropriate to the Mid-Atlantic region. At the FSP, seven field cropping systems were established in 1996, including till, no- till and organic systems that use various combinations of synthetic fertilizer, chicken manure, and legume sources of N. The cover crops (legumes and non-legumes) in the organic systems are not incorporated into the soil prior to planting the cash crop; instead, the cover crops are killed either by crushing or mowing. We hypothesize that these reduced tillage organic systems increase C and N retention relative to the synthetic till and no-till systems. We will present data collected to test this hypothesis and to begin investigating mechanisms responsible for soil N and C changes.