Spatial variability of soil nutrients and site-specific nutrient management

摘要

Spatial variability is a natural attribute of soil (Ball, 1968), which developed with soil formation processes and their interactions. Some differences in soil parent matter, irrigation, climate and animal activities (including human being) often result in variability of soils, even in a small scope (Jenny, 1941). In most cases at present, a field is often treated evenly, assuming there is no variability in the field. But in reality, there are often differences in soil fertility, topography and management. Fertilizers are usually equally applied on a whole field, resulting irrational fertilization in some parts of the field, causing low fertilizer using efficiency and low profit (Carr, 1991). With development of computer science, globe positioning system and variable rate technology, it is now possible to optimize agricultural inputs to each part of a field based on soil variability in order to increase crop yield and benefit, and to protect the environment. Precision agriculture is a comprehensive management system with combined use of GIS, GPS, RS and computer technologies (Wang, 1997). In principle, precision agriculture is suitable for any type and scale of agriculture production with some necessary adjustment in techniques (Reetz, 1994; McBratney, 1995). It is estimated that the precision agriculture will be the popular model for agriculture production in next century.