The difficult part is estimating how much of the total soil nitrogen pool, which is mainly in the unavailable form, will become available over the crop growing period. If after a legume pasture, for example, clovers or lucerne, or a legume crop, good rates of nitrogen mineralisation are likely. A legume crop, on average, leads to a build-up of nitrogen by around 50kg/ha. Much of this is likely available for the following crop.
