Using field and crop characteristics for site specific nitrogen management on winter wheat crop

摘要

A study on the agronomic, economic and environmental impact of site specific nitrogen management for a winter wheat crop was realized in France as part of an European Union Research project (IN-SPACE).This study is based on the one hand on information collected from a field of 6.2 ha, and , on the other hand, on simulations that take into account the climatic variations of 30 yrs. The information collected from 1994 to 1996 was based on yield maps and on grid sampling (physical and chemical analysis, soil N residue measurements). They showed that the main variation parameter on this field is soil depth. So the field was divided into four zones with the help of the criterion available water based on soil depth and water retention characteristics: zone 1=100 mm, zone 2=80 mm, zone 3=60 mm, zone 4=40 mm. The third year, site specific N fertilization was applied with a prototype spreader that is able to spread different rates on different zones in the field. The rates were calculated with the N balance sheetmethod, used on each zone of the field as if they were four different fields. Site specific management was compared with a uniform one, which corresponds to the calculation of a single rate in the field with the balance sheet method. The results of the 1996-1997 season do not show any significant differences between the two N managements, but the climatic conditions of this year were very uncommon. A severe drought started on early spring. These results correspond to one of the two worst on100 simulated scenarios.