| Currently, soil acidification has been plagued, soil acidification causes deterioration of soil quality, affecting crop growth, thus solving the problem of soil acidification has been a hot topic in soil science and environmental science among research workers, the research changes on soil acidity after adding crop stubble exists differences and specific effects of different stubble on s-oil acidity is unclear at the same time. Therefore, in this study we chose the stubble of soybeans, corn, millet, peanuts and sorghum five crops, selected the black soil in Jilin Agricultural University as the experimental field test soil, and studied the variation of soil pH of the soil cultivation under different crop stubble adding and the conditions of different amounts stubble, by the results of the data analysis, the conclusion is as follows:(1) After adding the five crop stubble, the pH of soil rose in the early stage and fell in the late stage, and the data reached the maximum in the first two months. In a short period, the soybean stubble 20 g / kg caused the biggest increase in soil pH, sorghum stubble 15 g / kg, followed by the rate of increase were 0.73 and 0.68(P <0.05). At the end of the incubation time, the soil pH those added soybean stubble 15-20 g / kg, corn stubble 20 g / kg, millet stubble 20 g / kg and added sorghum stubble 15-20 g / kg was significantly higher than other treatments, pH were above 5.60, compared with control group the average increase reached more than 0.56(P <0.05). Adding crop stubble can significantly reduce soil exchangeable acid and exchangeable Al3 + content, all the soil and crop stubble add group were added in the stubble after second months reached the lowest value, the addition of soybean stubble 20 g / kg of exchangeable Al3 + decreased most greatly, compared with the control group(0.465 mol / kg), reduced 0.244 mol / kg(P <0.05). At the end of the incubation period, soil exchangeable Al3 + content with the addition of soybean stubble 15-20 g / kg, corn stubble 20 g / kg, millet stubble 20 g / kg and sorghum stubble 15-20 g / kg were below 0.24 mol / kg, relative to the control group(0.617 mol / kg), the reduced rate were 0.378 mol / kg or more(P < 0.05).(2)Soil organic matte after adding five crop stubble rise in the first three months, but fall later. In the short term, add peanut stubble 20 g / kg and sorghum stubble 15 g / kg increases soil organic matter is greatly. Compare to the control group, the rate of increase were 43.68 g / kg and 42.89 g / kg(P <0.05). At the end of the incubation time, adding different crop stubble soil organic matter content were significantly higher, but different amounts of the same kind of stubble has no significant change in the law. Comparing organic matter content of soil added with different kinds of stubble, we can see that the organic matter content of soil added with sorghum stubbleis higher than other treatments, the effect of soybean stubble add into soil to enhance the organic matter is the worst.(3)Add the crop stubble can significantly improve the soil cation exchange capacity, and the cation exchange capacity is larger in the early but fall later. At the end of the incubation period, the cation exchange capacity has no significant change in the law. Compare to the control group, the base saturation of soil after adding different crops stubble has increased, and the first three months of the value is relatively high, the later fall. At the end of the incubation time, although the soil base saturation of soil added five crop stubbles are higher than the control group, but not significantly different. Adding stubble into soil increase the exchangeable calcium content most evident.In the end of the incubation time, soil exchangeable calcium content of the soil added five crop stubble was significantly higher, and the difference was significantly(P <0.05). On the whole, the effect of peanut stubble on exchangeable Ca is the worst.(4) The study of soil buffer performance shows that in the end of the incubation time, the buffering capacity of soil stubble reached 4.00 cmol /(kg ? pH) or more when add the corn stubble 20 g / kg, peanuts stubble 15-20 g / kg, millet stubble and sorghum stubble into soil. Compared to the control group(2.98 cmol /(kg ? pH)), the rate of increase were 1.02 cmol /(kg ? pH) or more. And can be seen, the soil buffer capacity after adding sorghum stubble was better than adding other crop stubble soil.(5)Correlation analysis showed that after adding crop stubble, the soil pH and cation exchange capacity, base saturation and exchangeable calcium were very significant positive correlation, after adding crop stubble, it influenced of the soil exchangeable calcium content, while the change of exchangeable calcium impacted on the base saturation and cation exchange capacity content, thereby it affected the soil pH, it explained that the main reason of changing soil acidity is the exchangeable calcium, the cation exchange capacity and the base saturation; After adding crop stubble, the soil buffering capacity and organic matter was significant positive correlation, it was not obvious with the performance of the exchange correlation, and it showed that the main factors affect of the buffer capacity size is the soil organic matter content.In summary, adding crop stubble can improve the status of soil acidification significantly, the facilities of crop stubble can obviously reduce the soil exchangeable Al3 + content. The magnitude of pH of the soil added soybean stubble is the maximum in the short-term, but poor in long-term results. From the results of long-term effects of different stubble impact on soil, the orghum stubble increase the rate of soil pH, cation exchange capacity, exchangeable base cations, especially the organic matter and the exchangeable calcium content are located in the front of five crop stubble. The study on soil buffering properties also showed that the buffering capacity of adding sorghum stubble soil was significantly better than the other groups. Therefore, add sorghum stubble is preferred to improve the soil acidity. |
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