SIMULATION OF NITROGEN IN SOIL AND WINTER-WHEAT CROPS - A MANAGEMENT MODEL THAT MAKES THE BEST USE OF LIMITED INFORMATION

A model that simulates changes in mineral N in the soil and N uptake by crops has been adapted to require as little detailed information as possible so that it is useful as an aid to management. The adapted model, which was developed in the UK, was tested against data from six experiments on winter wheat in the Netherlands. It proved reasonably successful in simulating the amounts of mineral N found in the soil in early spring and the changes that resulted from applying small amounts of fertilizer N in February. It was much less successful in simulating the effects of later, larger applications of N, mainly because the mineral N measured in the soil did not seem to respond to these applications. The uptake of N by the crops and their production of dry matter were simulated very well in some cases and rather less so in others.