Simulated Study On The Impacts Of Different Resource Irrigation Water Leaching Continuously Soil On Base Cation

The excessive acidation is one of main barriers of productivity of land in south, China. Because of limited suitable and with lower productivity level, the excessive acidic soil is used to serve as the land resources that agriculture produce unwillingly. With the increasing pressure of distinct contradiction between population and the land resource, one of the main approaches to improve productivity of southern land and solve the contradiction with population and the land resource is studying cause of soil acidification, keeping soil from excessively acidification, resuming and managing the excessive acid soil.Although there are many reasons for acid soil, such as regions, utilizing conditions and types of soil, the most important factors that affect soil acidification are leaching loss of exchangeable ions and saturation equilibrium. There have been many studies about long-term acid rain that leading to soil acidification. So far, little attention has been paid to soil acidification by no acidic rain, different mineralization degree water and composition of irrigated water. In Chongqing area, soil acidification on slope tilth(\vithout irrigation condition) is widespread with outstanding and the extreme pH value in soil can be lower than 3.8,however, soil excessive acidification is relatively abnormal in bottomland and slot valley region with better water resource and better irrigation condition. The reason for the difference is that slope tilth is irrigated by natural rain mostly while bottomland and slot valley region are mainly irrigated by the earth's surface(irrigation water) or groundwater with higher mineralization degree.We have sequential extracted the particular soils (acidic soil, neutral pH soil, calcareous soil) by simulated rainwater and different source irrigation water (Mingjiang River, purple rock area reservoir water) and measured base cation and relative index changes in soil and filtrate. We expected to get leaching loss and cumulation characteristics of exchangeable cation under long term leaching with different leacheate, discussed the influence of soil acidicprocesses and the probability of resuming the strong acidic soil.The results of the study were indicated as follows: 1.Changes characteristic of base cation in soils leaching with different leacheate(1) Conductance of filtrate is the far larger than leacheate during prophase and with the hours extension, it descended gradually and tended in the stability, which express that the soil through, strong machine offense can accelerate the base cation leach to lose. The conductance change ratio of different filtrate followed in the order simulated the reservoir water>simulated Mingfing River's water> simulated rainwater. At the end of the experiment, in addition to conductance of filtrate from simulated rain keeping the larger than simulated value, the others were near to simulated value. Conductance changes for different soil treatments were in an order of purple add soil> purple calcareous soil> purple neutral soil> yellow cold sand soil.(2) Leaching with simulated rain water, soils leached out Ca2+, Mg2+, K+, Na+, Leaching with simulated Ming/iang River's water: net loss of Ca + absolutely predominated in purple neutral soil and purple calcareous soil while cumulation of Ca2+ predominated in yellow cold sand soil and purple acid soil. Soils cumulated K+, excep for yellow cold sand soil. Except for purple calcareous soil, soils cumulated Na+. Leaching with the simulated reservoir water, soils accumulated Ca2+, Mg2+, K+, Na+. Ability to cumulate Mg2+, K+, Na+ leaching with the simulated reservoir water was better than the simulated Ming/iang River's water.(3) With three dynamic equations (Elovich, Parabola, Hyperbola dynamic equation) to respectively imitate the process of net missing and storage accumulation of Ca2+, Mg2+, K+, Na+ changing with days. The simulant effect of calcium with Elovich equation is the best, Parabola equation is the worse, Hyperbola equation is the worst. The three dynamic equation...