Research On The Storage Capability Of Nutritive Elements In Cultivated Soils In Jilin Province

The storage capability of nutritive elements(mainly N, P, K) is an important index of soil fertility evaluation. Some researches showed that the excess fertilization of chemical fertilizer was a major cause of agricultural nonpoint source pollution. When the amount of fertilizer is larger than the required amount of crop absorption and the storage capacity of soil, it will not only cause the waste of fertilizer, but also cause agricultural nonpoint source pollution. In this study, three main cultivated soils in Jilin Province are taken as test objects. Through the laboratory simulation experiments, the storage capacity of nitrogen, phosphorus and potassium in soil was studied, and the main factors affecting soil cation exchange capability was discussed. This purpose of this research is to provide a theoretical basis for rational fertilization and agricultural non-point source pollution control in Jilin province. The results of the study summarized as follows: 1. Different type of soil has different immobilization amount of ammonium. In black soil it’s 46.15g·kg-1, in chernozem it’s 44.82g·kg-1, in albic soil it’s 43.86g·kg-1, the order is black soil > chernozem > albic soil. The ammonium adsorption in the soil is mainly exchange adsorption, the amount of exchangeable ammonium in ammonium storage capacity is in the proportion of 99.6% in black soil, 99.96% in chernozem and 99.73% in albic soil. The amount of fixed ammonium in ammonium storage capacity is in the proportion of 0.4% in black soil, 0.04% in chernozem and 0.27% in albic soil. 2. Different type of soil has different immobilization amount of phosphorus. In black soil it’s 110.3mg·kg-1, in chernozem it’s 104.3mg·kg-1, in albic soil it’s 135.6mg·kg-1, the order is albic soil > black soil > chernozem. The adsorption of phosphorus in the soil is principally ligand adsorption, its amount in phosphorus storage capacity is in the proportion of 69.7% in black soil, 84.6% in chernozem and 71.4% in albic soil. Only a few is exchange adsorption, its amount in phosphorus storage capacity is in the proportion of 30.3% in black soil, 15.4% in chernozem and 28.6% in albic soil. 3. Different type of soil has different immobilization amount of potassium. In black soil it’s 450.35mg·kg-1, in chernozem it’s 72.39mg·kg-1, in albic soil it’s 135.6mg·kg-1, the order is black soil > albic soil > chernozem. The potassium adsorption in the soil is mainly fixing absorption, the amount of slowly available potassium in potassium storage capacity is in the proportion of 80.33% in black soil, 80.00% in chernozem and 84.62% in albic soil. The amount of rapidly available potassium in potassium storage capacity is in the proportion of 16.67% in black soil, 20.00% in chernozem and 15.38% in albic soil. 4. Soil organic matter can significantly affect the soil cation exchange capacity. Without changing other properties of the soil, the removal of the organic matter of the three tested soil could significantly reduce the cation exchange capacity of the soil. 5. Different soil particles had different effect on the performance of soil cation exchange. The sand of three tested soil had little effect on the cation exchange capacity of the soil. It can hardly provide cation exchange capacity. The silt and clay of chernozem can affect the soil cation exchange capacity. In Black and albic soil, only the clay can provide larger cation exchange capacity. 6. Different mineral composition of soil had different effect on soil cation exchange performance. The clay mineral composition of the three tested soil contains illite, montmorillonite, kaolinite and vermiculite. Different type of mineral composition has different effect on adsorption capacity of different nutritional elements.