This test provides an accurate measurement of total Nitrogen in the crop. The crop needs to be sampled using a quadrat of known area (eg 0.5 m x 0.5 m) and all above-ground biomass cut from within is send to the laboratory. By measuring the dry matter of the samples as well as the total N, it is possible to calculate the crop N offtake. Results are presented in kg N/ha.
This test is often used in combination with soil mineral N.