It is important to accurately meet a crop’s nitrogen (N) requirement, as under-fertilisation costs yield, and over-fertilisation wastes fertiliser and can cause environmental problems from N leaching. In Denmark, crop N requirements are set by legislation as norms based on field trials with an increased N application. The norms are general and cannot consider conditions on individual fields. In the digital tool for precision agricul-ture CropManager, the N-Tool-Precise model can customise the N requirement in winter wheat using satel-lite data combined with cultivation data from electronic fertiliser planning programmes. Thus, N uptake can be determined from satellite measurements of the vegetation index NDRE based on crop light reflectance. The model enables adjustment of N application during the growing season. To this end, a split dose fertiliser application is necessary. The sum of N applied at the start of crop growth and in mid-April must be about 50 kg N per ha below the expected N need as stated in the norms. It is estimated that by using the N-Tool-Precise model, additional yields of 3 hkg per ha may be achieved and N leaching can be reduced by 3 kg N per ha.