NITROGEN DYNAMICS OF CROP AND SOIL SUBJECTED TO DIFFERENT WATER AND NITROGEN INPUTS, INCLUDING DAILY IRRIGATION AND STEADY-STATE FERTILIZATION MEASUREMENTS AND MODELING

Major carbon and nitrogen fluxes through crop and soil were studied in a series of field experiments. Barley, winter wheat, a grass mixture cut for hay and the energy crop reed canary-grass (Phalaris arundinace a) were studied. The treatments ranged from drought to daily irrigatio n/fertilization with high doses of water and nitrogen. Crop biomass an d nitrogen dynamics above and below ground and incident light as well as soil temperature, moisture and mineral N content were monitored. Li tter decomposition experiments were also performed in the field. The r esults were used to parameterize, validate and improve a set of soil/p lant simulation models. Selected experimental results and experiences gained from the water, C and N budgeting and modelling work are presen ted.