APPLICATION OF A SIMPLE MANAGEMENT MODEL TO SIMULATE WATER AND NITROGEN DYNAMICS

A simple model for management purposes was applied to simulate water and nitrogen dynamics in the plant soil system of two investigation sites in Lower Saxony. The model considers the main processes of nitrogen mineralization, denitrification, water and nitrogen movement, plant growth and water as well as nitrogen uptake by plants. All soil parameters are generated automatically by the model using basic soil information. Parameters for the plant growth model have been used unchanged for all cereals. For sugar beets some rough adjustments have been made to change partitioning of assimilates within the plant. All other parameters are fixed in the model. Results of 2- respectively 3-year simulations were compared to experimental data of soil water content, mineral nitrogen in soil, plant biomass, leaf area index and nitrogen uptake by plants. The model fits well the nitrogen dynamics on the sandy site, but not on the loamy site. Biomass production agrees well for cereals except the phase of senescence, while biomass production of sugar beets was underestimated.