M. H. Wang, Farmers Need Real Information, IChina, vol.13, p.19, 2006.

H. Zhang, F. C. Li, X. M. Ma, R. Gao, B. Xia et al., Design and Realization of GIS- Based County Testing Soil for Wheat Formulated Fertilization System, Jour. Hen. Agri. Uni, vol.5, pp.566-569, 2008.

H. Zhang, L. Xi, H. Yu, S. P. Xiong, H. B. Qiao et al., Design Of Decision-making System about Wheat Survey and Directions for Soil Based on GIS in County, 3th Computer and Computing Technologies in Agriculture, pp.661-670, 2009.

J. D. Sheng and R. Li, An Information System of Soil Nutrition Management and Crop Fertilizer Recommendation Based on GIS. Soils, pp.77-81, 2002.

L. Y. He and J. Miao, Research of Farmland Resource Management and Application Model Based on Web GIS, 3th Computer and Computing Technologies in Agriculture, pp.8-14, 2007.

K. X. Wei, Henan TuRang Dili, He Nan, 1995.

L. Xi, X. M. Ma, F. C. Li, H. B. Liu, Y. N. Ren et al., Design and Implementation of Crop Growth Simulation System Based on Techno-Componentware Model, Jour. Hen. Agri. Uni, vol.3, pp.317-320, 2005.

H. Zhang, Research of Crop Production Potential System Based on OMT and Software Component Technique. The PLA Information Engineering University, 2009.

L. P. Yang and J. Y. Jin, Study on the Correlation between ASI and Routine Method to Determine Soil, and the Conventional Chemical Methods

G. Y. Xiong, D. B. Liu, and F. Chen, Study on the Correlation between ASI and Routine Method to Determine Soil Available P and K and Ammonium Nitrogen, Soil. Fert, vol.3, pp.73-76, 2007.

H. T. Wang, D. P. Bai, and M. C. Chen, A Systematic Study on Nutrient Status and Its Application in Balanced Fertilization, Jour. Shan. Agri. Scie, vol.4, pp.31-36, 2001.

S. Z. Zhou, Y. Dai, and M. Y. Yao, Application of Dissimilar Subtraction Method of Soil Fertility in Recommend Fertilizer Practice for Maize Planting in Yellow Clay Soil, Gui. Agri. Scie, vol.6, pp.34-36, 2003.

G. D. Xie and S. H. Chen, Spatial Continuous Variation of Environment and Precision Agriculture, pp.18-19, 2005.