Optimizing nitrogen fertilizer application to irrigated wheat. Results of a co-ordinated research project. 1994-1998

This TECDOC summarizes the results of a Co-ordinated Research Project (CRP) on the Use of Nuclear Techniques for Optimizing Fertilizer Application under Irrigated Wheat to Increase the Efficient Use of Nitrogen Fertilizer and Consequently Reduce Environmental Pollution. The project was carried out between 1994 and 1998 through the technical co-ordination of the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture. Fourteen Member States of the IAEA and FAO carried out a series of field experiments aimed at improving irrigation water and fertilizer-N uptake efficiencies through integrated management of the complex Interactions involving inputs, soils, climate, and wheat cultivars. Its goals were: to investigate various aspects of fertilizer N uptake efficiency of wheat crops under irrigation through an interregional research network involving countries growing large areas of irrigated wheat; to use 15N and the soil-moisture neutron probe to determine the fate of applied N, to follow water and nitrate movement in the soil, and to determine water balance and water-use efficiency in irrigated wheat cropping systems; to use the data generated to further develop and refine various relationships in the Ceres-Wheat computer simulation model; to use the knowledge generated to produce a N-rate-recommendation package to refine specific management strategies with respect to fertilizer applications and expected yields