Abstract: According to the result of soil sampling and test, soil properties map can be achieved by interpolation. After that, a prescription map can be generated to conduct variable-rate fertilization. This process is the core of precision agriculture. It can not only save fertilizer, but also improve economic and environment benefit. The system which is based on Geography Information System (GIS) can: 1) interpolate soil properties map by Kriging method; 2) integrate yield, meteorological data and soil data into a database; 3) couple GIS with knowledge model, such as crop potential productivity and balanced fertilization model; 4) generate prescription map and transmit by Web. The study constructs the basic frame and process flow of precision agriculture based on knowledge model and WebGIS, improves the rationality and reliability of prescription map, implement to generate and release a prescription by Web, and make it easy to achieve a prescription map.

Key words: knowledge model, WebGIS, Prescription map, Variable-rate fertilization