Modelling crop root development and nitrate uptake

Summary

Nitrate leaching from agricultural areas is a political and environmental issue at both local scale in Denmark and at global scale. Plant-available nitrogen and nitrate in the rooting zone in the growing season is necessary in order to obtain satisfactory crop yields. However, surplus nitrogen leads to a risk of nitrate losses through leaching and denitrification. In addition to artificial applications of nitrate, nitrate is produced by mineralisation processes in the soil from plant residues and soil organic matter and by nitrification. Therefore nitrate losses can be difficult to control. This thesis investigates root growth in arable and vegetable crops through construction and improvement of existing models for determining root growth and associated N uptake. The models provide an insight into nitrate dynamics in the soil matrix, and can be used to predict plant yield and N uptake and changes in different soil N pools. Here, the models were used for analysing different physical and biological processes in soil. This was combined with analysis of model construction and parameterisation of crop modules, root sub-modules and soil organic matter pools for predicting nitrate leaching and retention.