Abstract: Soil Identification and Optimum Fertilizer Application is an excellent creation to apply modern mathematics, computer technology to the area of comprehensive fertilization. The most conspicuous character of this technique is, under the prerequisite without analysing soil nutrition, farmer needs only provide the information about the crop yield, fertilizer applied in last croping season in a given land, the special microcomputer will rapidly calculate the optimum fertilizer amount and forecast the crop yield in present croping season in the same land, thus save the labour, material and financial expenses. This technique has been popularized to the paddy field in Fujian for 4 years(from 1987 to 1990,8 croping seasons) ,the accumulative popularized area reached 16. 7 million Mu, the grain yield increased in 4-year period is more than 0. 38 million tons, the total economical benefit reached 260 million RMB Yuan. This technique has also been extender to Jiangxi, Yunnan, Guizhou, Hubei provinces, and all received good results.