Using yield maps and intensive soil sampling to improve nitrogen fertiliser recommendations from a deterministic model in the Western Australian wheatbelt

Abstract

A field-scale experiment was conducted to determine the ability of a deterministic model developed for Western Australian wheat farmers to guide site-specific applications of nitrogen fertiliser. The results indicated that site-specific information of achievable yield improved the prediction accuracy much more than information about soil nitrogen — even though the latter was more costly to acquire. When applied together, these sources of information improved the prediction accuracy of the model markedly, explaining about half of the variation of yield response to nitrogen. However, the model failed to explain a substantial portion of site-specific variation, even with this intensity of information. This failure indicates the difficulty of representing complex biological systems with simple functional models.