We defined a new concept of field-level delta nitrogen (N) losses (D NL) as a comparison between management scenarios. We defined delta nitrogen losses (D NL) as a function of improved N use efficiencies of field management scenarios that reduce the average N inputs and/or modify other management practices thus lowering N losses from a farm field. The D NL refer to potential downstream reductions in nonpoint source nitrogen loading of streams or other water bodies and/or in reduced loading of the atmosphere with N-associated greenhouse gases from agriculture. Nitrogen credits as traded on the Communities Market commonly refer to discounted reductions in agricultural nitrogen losses that apply to a project downstream from an agricultural area. We used a newly released Windows XP version of the Nitrogen Losses and Environmental Assessment Package (NLEAP) with a Geographic Information System (GIS) capability (NLEAP-GIS) to assess no-till systems from a humid North Atlantic US site, manure management from a Midwestern US site, and irrigated cropland from an arid Western US site. The new NLEAP-GIS can be used to quickly identify the best scenario that shows the greatest potential to maximize field-level D NL for environmental conservation.