VALIDATION OF A SIMULATION MODEL FOR CARBON AND NITROGEN DYNAMICS IN SOIL IN A FIELD TRIAL

A simulation model for C and N turnover in soil was tested against measured data derived from a field experiment. Carrot was grown on a loamy sand with widely differing organic/mineral fertilizer applications. The simulation calculations reproduced the dynamics of mineral nitrogen at 0-60 cm within +- 20 kgN/ha, Changes in carbon content for a 5 year period to within +- 0.1% C_t. It is concluded from these results that net nitrogen mineralization is correctly estimated. In the future this model may be used to better adapt nitrogen supply to the demand of plants and to minimize the risk of nitrogen losses.