Technical Abstract: Rapid and accurate measurement of soil organic matter content and nitrogen, phosphorus, potassium and other nutrients is the basis for variable rate fertilizer application in precision agriculture, and it is also a difficult problem that scientists have been committed to resolving. On the basis of analyzing the needs for real-time measurement of soil attributes, this paper describes major soil attributes to be measured in soil testing and commonly-used testing methods, including traditional chemical analysis, methods based on electro-optical dispersion and electrochemical sensors, and indirect measurement of soil electrical conductivity. More emphasis is given to the review of the basic principles, laboratory studies, prototype development, and field experiments of near-infrared spectroscopic sensors that have made significant progress in recent years. Finally, the paper discusses some of the scientific problems that need to be solved to achieve real-time in-field determination.