The Effect Of Mulching On Maize Straw Decomposition Rate In Loess Plateau Area

The climate of Loess Plateau area is dry, low temperature and lack of rain, owns the typical rain-fed agriculture mode, natural precipitation is the only source of crops water requirement. Technology of film covering is an important measure for crop irrigation, can effectively improve the water and thermal environment of soil, has remarkable effects on moisture keeping and steam inhibiting. However, perennial continuous film is easy to cause the decline of soil fertility, the consumption of soil organic matter, straw returning technology can effectively improve this situation. There are lots of researches about returning straw to soil improving soil physical.chemical properties and soil fertility, but the study of straw decomposition rate of Loess Plateau semi-arid and semi-humid area has not yet been established.In this paper we selects five typical test points of semi-arid sub-humid areas in Loess Plateau, technology of straw soil-incorporation combined with film-mulehed furrow-ridge cropping, discusses the annual decomposition rate after straw into the soil, it can provide a strong theoretical basis for further decomposition of straw. This experiment sets up three main treatments:1, CK;2, S;3, S+M, and take Chongxin area as an object, to explore the effect of straw soil-incorporation and mulching on soil moisture and microbial activity of surface. The main experiment in this thesis is to determine the decomposition rate of straw in five regions, mainly using the nylon bag method. According to the result of experimental data:1、The one year’s cumulative decomposition rates of five test points which were not covered with film are largely different, the decomposition rates are varying from30%to45%, the average decomposition rate is40%. The decomposition rates of film mulching treatment are varying from40%to60%, with an average rate of50%. When compared with no film treatment, the film mulching treatment can raise the one year’s cumulative decomposition rate by25%.2After two years of decomposition, two years cumulative decomposition rate of no mulching treatment is60%-65%,the average is64%, two year cumulative decomposition rate of mulching is 70-80%, the average is75%, two years accumulated decomposition rate of mulching is higher up to19%than no mulching conditions, These results show that the film mulching can increases the mineralization rate of fresh organic matter in soil.3, Film mulching (set covering treatment with film before winter) can improve the soil moisture, soil temperature during fallow period and early growth period,thus can increase microbial activity in soil significantly. This is the main reason of film mulching increasing mineralization rate of the fresh organic matte in soil.