WELL_N™ for MORPH uses data gathered before and during the growth of a crop to give Nitrogen fertiliser recommendations. An optimum recommendation for fertiliser requirement is given based on yield. Optimum Nitrogen fertiliser defined as the level where a further 10kg/ha of Nitrogen fertiliser increases yield by less than 1%. The WELL_N™ model provides estimates of the fresh and dry crop yield, Nitrogen content of crop and its residues. It also provides estimates of leaching since the start of the run and soil mineral N states at harvest, for different N fertiliser rates. This additional information enables alternate strategies of fertiliser application to be formulated.