Abstract: The balanced fertilization models based on soil fertility were built by field experiment for paddy field and upland of red soil. The fertilization decision-making supporting systems was developed at Yujiang County, Jiangxi Province, by inserting MapObjects component into the Visual Basic development environment and combining the techniques of database ComGIS, decision supporting systems. According to the basic information of geography, soil and agricultural economy, the spatial variations of soil nutrient were analyzed. The fertilization decion-making supporting system supply fertilization instruction for the paddy soil and upland at the county scale based on the minimum unit of fertilization.