The nitrogen loss process is complicated, but producers need to be able to make decisions about applying additional nitrogen that are at least in the ballpark. And they need to be able to correctly prioritize which of their fields need the largest additional applications of nitrogen fertilizer. The nitrogen loss scoresheet (PDF) can provide some insight.
Nitrogen loss aerial galleries
Galleries of aerial photos showing fields with nitrogen deficiency symptoms.
Rainfall maps to identify areas at risk of nitrogen loss.