Patent ID: 8520891

Claim:
A method of determining a nitrogen fertilization rate of a crop field at mid-season to ameliorate nitrogen deficiency using a spatially referenced map of relative green values (RG), wherein each RG comprises the reflectivity of green light at a location in a canopy of the crop field relative to a reference RG, the method comprising: a. estimating an economically optimal nitrogen rate (EONR) corresponding to each RG of the spatially referenced map by substituting each RG into the equation EONR= C 3 ×RG− C 4 wherein C 3 and C 4 are empirically derived constants; and b. mapping each EONR corresponding to each RG onto a spatially referenced EONR map; wherein each EONR comprises a recommended amount of nitrogen per unit area to be applied at mid-season in order to minimize a predicted crop yield loss due to nitrogen deficiency.