Determine the nitrogen optimum of plants.
The Yara-N-tester works according to an optimal measurement principle: the farmer determines the chlorophyll content, or green colouring, on at least 30 leaves. For this the youngest, most fully developed leaves are chosen. Since each variety and crop has its own characteristics the measurement value is offset with a correction factor. The farmer then enters the corrected value into the fertilisation recommendation table of YARA for the nitrogen recommendation for the tested area. These maps for variety correction and fertiliser recommendation are updated every year before the start of the fertilising season.