County-Level Estimates of Nitrogen and Phosphorus from Commercial Fertilizer for the Conterminous United States, 1987-2006

This data set contains county-level estimates of nitrogen and phosphorus from fertilizer,
for both farm and nonfarm uses, for the conterminous United States, for 1987 through
2006. State-level farm and nonfarm nitrogen and phosphorus were derived from the
Association of American Plant Food Control Officials (AAPFCO) commercial fertilizer
sales data. State estimates were then allocated to the county-level using fertilizer
expenditure as county weights for farm fertilizer, and population density as county
weights for nonfarm fertilizer.