Effects Of Different Amount Of Crops Straw Burning On Soil Environment And Grain Yield

Straw burning has a strong impact on soil ecological balance. According to indexes ofsoil microbes, physical and chemical properties and mean grain yield, this study exploredeffects of straw burning on the soil fertility under three different burning regimes in thewheat-corn rotation fields of Sanyuan county, Shaanxi province. Results showed that:（1）Effects of straw burning were mainly exerted in the0-5cm top soil while only smalleffects were investigated in the soil depths below5cm, and straw burning reduced soil total N,NOx－-N, NH＋4-N, moisture, organic matter, fungi, actinomyces, bacteria in the0-5cm topsoil by the mean of4.73%,9.28%,9.32%,14.68%,14.56%,59.92%,63.38%and70.29%respectively; total P, total K, available P and available K increased by an average of9.78%,4.63%,14.01%and34.00%. Because the soil bulk density was mainly influenced bysoil parent material, soil structure, porosity and so on, so a short period of time, effect ofstraw burning on soil bulk density is not obvious.（2）Straw burning soil black carbon content changed significantly, but its effect mainlyin0-5cm top soil, and almost has no influence in the soil depths below5cm. Compared to thecontrol group (CK), black carbon content of experimental group0-5cm in surface soilincreased by an average of24.87%.（3）Straw burning quantity have significantly negative correlations with corn yield andaboveground biomass. Because the burning of straw, soil ecological environment has beenseverely damaged, the next crop germination, seedling growth was affected to a certain degree,and affect the next stubble crops yield and biomass. Compared to the control group (CK),straw burning caused lower crop yield by an average of14.07%, aboveground biomassdecreased by an average of14.51%.（4）Straw burning on soil environment and crop yield is affected by a number of strawburning affect. Straw burning quantity have significantly negative correlations with s soilbacteria, fungi, actinomycetes, moisture content, organic matter content, total nitrogen, nitratenitrogen, ammonium nitrogen content, grain yield and aboveground biomass, while havesignificantly positive correlations with soil total P, total K available P, available K and blackcarbon.