The WELL_N model developed at Horticulture Research International (HRI) Wellesbourne is a major step forward in optimising nitrogen fertiliser usage and has been available to growers through the Horticultural Development Council in England and Wales since July 1994 and Scotland since early 1996. WELL_N is a sophisticated, but easy to use computer model, which can predict crop nitrogen requirements for 24 arable and horticultural crops.
The amount of nitrogen available to the crop depends on many factors including soil type and structure, temperature, local weather conditions, leaching, etc, while the crop's actual requirement is dependent on its growth and the efficiency with which the individual plant root system is able to take up the nitrogen from the soil. Against such a complex background it is not surprising that many crops either have insufficient nitrogen to maximise their potential in terms of quality as well as yield, while other crops are unable to use all the applied nitrogen, which is subsequently wasted and can lead to environmental pollution.
When calculating fertiliser recommendations WELL_N takes account of all the major factors affecting the nitrogen status of field and crop including expected yield, the geographical position of the field, local weather, and soil texture, as well as the contribution of nitrogen from previous crop residues. WELL_N can be used to interpret measurements of soil mineral N. Using readily available information WELL_N calculates nitrogen fertiliser requirements for most field crops grown in the UK, together with the likely final nitrogen content of the crop and the amount of nitrate which could potentially be leached into ground water from specific fertiliser applications. The model can be run in two modes to provide fertiliser recommendations :
The WELL_N model is likely to be adapted for the Morph environment (Web information system of HRI) in the next 12 months.