Variations of soil nutrient content and fertilization in Guizhou

In order to find out the variations of soil nutrient content in farmlands of Guizhou, a survey of soil and fertilizer was conducted again in 1998, based on the survey results of 1985 Results showed that the contents of soil organic matter, nitrogen and phosphorus in paddy fields increased year after year, under the application of chemical fertilizer combined with organic manure, even if the chemical fertilizer played a leading role in the supply of nutrient In upland fields, the soil phosphorus content was also increased, whereas soil organic matter and potassium were obvious reduced The contents of soil microelementsavailable boron, zinc and molybdenum generally increased in upland and paddy fields Hence it is necessary to increase the application of potash fertilizer and to pay attention to the use of organic manure, the return of straw to farmland and the control of soil and water losses in order to improve soil fertility and to promote the development of sustainable agriculture