VARIATIONS OF RED EARTH FERTILITY AND AVAILABLE TECHNIQUES OF FERTILIZATION

The longterm monitoring soil fertility on using nitrogenous fertilizer, phosphate fertilizer, potash fertilizer and organic manure was conducted on the bases on longterm monitoring soil fertility in Qiyang County. Results indicated that on the treatment of without fertilizer and the treatment of using only one fertilizer, the plant could not grow normally, yield and soil fertility decreased year after year. On the treatment of NP and NPK, the plant could grow normally, yield increased, but the contents of available zinc and boron on soil decreased rapidly. On the treatments of MNPK and SNPK not only maintained the equilibrium of nitrogen, phosphorus and potassium, but also supplied some micronutrients into soil. So they are the main ways to increase yield and fertilize soil. On the treatment of IMNPK, the average yield of corn was 5124 kg/hm2, more than other treatments. But on this treatment, the wheat grew abnormally fast and lodged easily. On the wheat and corn rotation system, application of organic manure(or straw) combined with chemical fertilizers was an important way to gain high and stable yield of crop and to improve fertility of soils in the upland of red earth.