This EnviroAtlas dataset contains data on the mean synthetic nitrogen (N) fertilizer application to cultivated crop and hay/pasture lands per 12-digit Hydrologic Unit (HUC) in 2006 (EA_SNFA_Mean attribute). Synthetic N fertilizer inputs in 2006 were estimated using county-level estimates of farm N fertilizer inputs. We acquired county-level data describing total farm-level inputs (kg N/yr) of synthetic N fertilizer to individual counties in 2006 from the United States Geological Survey (USGS) (http://pubs.usgs.gov/sir/2012/5207/). These data were converted to per area rates (kg N/ha/yr) of synthetic N fertilizer application by dividing the total N input by the land area (ha) of combined cultivated crop and hay/pasture lands within [...]
