System modeling and control of automatically variable rate fertilizer applicator

Variable rate fertilization is the most important technical system of precision agriculture nowadays. The paper introduces the system modeling and control method of one kind of automatically variable rate fertilizer applicator according to the specific situation of China. The applicator makes use of spatial information technologies, such as GPS, GIS and RS, to adjust the application rate Of fertilizer controlled by step motor through single chip computer. Decision making modeling for variable rate fertilization, system control modeling for single chip computer and grid cell identification modeling for the tractor are the core models for the variable rate fertilizer applicator and introduced in detail in the paper. Experiments in the field show that the variable rate applicator works well and the control accuracy is less than 7%.