INTEGRATED WHEAT NITROGEN NUTRITION MANAGEMENT IN MOROCCO:A DECISION SUPPORT MODEL

摘要

Our study is geared towards the development of a decision support model for integrated wheat nitrogen nutrition management (GIN - BLE). This guide provides access, on a daily basis, to general information on wheat crop and wheat N nutrition and fertilization. Three major steps marked the conception of this model: - Literature review on current knowledge on wheat growth, nutrition and fertilization and crop response to different sources of N; - Data base construction using Access; and-Programming using Visual Basic. Main features of GIN - BLE deal with factors considered to be the most influential in determining final yields and wheat N nutrition. Subroutines include : - Wheat phenology : Simulates phasic development as related to variety, environmental factors and crop management; - Biomass accumulation and partitioning:Simulates leaf area index, dry matter production during each phase of wheat development, and biomass partitioning among different organs; - Grain yield: Calculates wheat population stand, spike population per unit area, grains number per mE, grain size and grain yield. - Water balance: Calculates soil water content. - Nitrogen balance: Provides orders of magnitude of N balance parameters. - N fertilization management: Provides wheat N fertilization recommendations. We assumed optimal conditions as a first step to limit variation factors and facilitate programming.GIN- BLE provides generalities on wheat crop,physiological features as well as a 《Help》 option that gives more details on subroutine conception and functioning. It allows rapid access to information on wheat growth and responses to N fertilizer in an interactive way. GIN-BLE test of performances allows comparison of simulated results to those observed in 5 irrigated field trials in Morocco. Validation revealed some very satisfactory results, strong correlations are observed between simulated and observed wheat development stages ( r = 0. 98 ; r =0.97 ), yield components ( r = 0.91 ; r = 0. 92 ; r =0. 95 ) and dry matter production and partitioning (r =0.90 to r =0.96).