Study On Application Of ComGIS-based Precription System For Variable-Rate Fertilization In Precision Agriculture

Variable-Rate Fertilizer Prescription is not only the premise of realizing the variable-rate technology in precision agriculture, but also the basis of variable-cultivation of fertilizer machine in the field. Based on the theory of variable-rate-fertilization in the world, software engineering and GIS technology, this paper studied and developed a ComGIS-based Prescription System for Variable-Rate Fertilization in Precision Agriculture in order to realize the variable-rate cultivation in field under the direction of fertilizer prescription. It realized the spatial interpolation software grounded on Geostatistics seamlesslly integrated with the system using the way of OOP and the technology of OLE/ActiveX based on COM. Using vector-grid spatial-overlap analysis to solve the limitation of the grid and general vector data structure in the course of creating prescription, it made fertilizer prescription founded on the main factor of soil nutrient and yield-target. Also it effectively integrated ComGIS with Expert System using the technique of loose coupling. Under the consideration of required fertilizer prescription data structure in the fertilizer machine, the vector prescription with the grid cells can integrate organically with fertilizer machine by adopting the Coordinate WGS-84 System.This system is developed through adopting the ComGIS MapObjects2.0, assisted by Visual C++ and Windows98/NT. It realized the following functions. It fulfilled the transforming from point data to polygon data and created the field soil nutrient spatial distribution graphics using the different kinds of interpolation ways. It integrated soil test nutrition data, object yield obtained by historical crop yields of past years, fertilization model and expert knowledge to realize intelligent decision and make field fertilizer prescription. With the card ATAFLASH, the prescription made by the system can be imported into the control computer of variable-rate fertilizer machinery and direct variable-rate controller to implement variable-rate fertilization.