Vegetable production generally bears the high risk of NO3 leaching into the ground water because vegetable crops are fertilized excessively with nitrogen. Reasons for excessive N dressing are that N supply from soil organic matter and plant residues are not rated accurately by growers and that NO3 is leached by excessive irrigation. The mineralization depends on environmental factors. Thus a prognosis for the whole growth period of a crop is risky, because weather cannot be foreseen.
Aim of the project is, to develop computer models 1) for N uptake of the crop, 2) for N mineralization of soil organic matter and crop residues.
The work is to increase the efficiency of nitrogen use, to minimize nitrate leaching and to improve the quality of field grown vegetable crops. Protocols have been developed for conducting field experiments under different climatic conditions. The same crop, iceberg lettuce, will be grown at all locations. The methodology has been established for measuring nitrate in the soil.
Furthermore, control instruments for irrigation will be developed and integrated with the first two models to control N supply to the crop. It is expected that split application by an appropriate fertigation system prevents NO3 leaching and increases uni formity of the crop. The use of computer models gives the opportunity to shorten the prognosis period and to fertilize and irrigate only if necessary.
Field experiments include vegetable crop production at varied N supply and addition of crop residues on different sites under the wide range of climatic conditions in North and South Europe and test of tools to control irrigation.