Keywords: Nitrogen, Phosphorus, Rice, Wheat, Greenhouse crops, Modelling.

This paper deals with application of mechanistic models to the development of fertilizer recommendations. Such models can be of great assistance in understanding how different factors and their interactions influence crop functions. The paper presents a framework in which the different processes considered in plant/soil models can be placed. Five examples of the employment of mechanistic models for recommendations are discussed: obtaining new recommendations for P-fertilisation of flower bulbs, management of (timing of) N-application in rice, two models on N-fertilisation of wheat, and finally a model on fertigation in glasshouse horticulture. Attention is paid to the type of customers the models should address.

Dr Peter de Willigen, Alterra, Green World Research, 6700 AA Wageningen, Netherlands.

19 pages, 8 figures, 1 table, 29 refs.