秸秆还田深度对土壤团聚体组成及有机碳含量的影响

为探究玉米秸秆还田至不同深度后对土壤团聚体及有机碳含量的影响,采用田间微区试验,将秸秆磨碎后分别还田至0～10、10～20、20～30、30～40 cm 4个深度土层,同时设置不还田对照,共计5个处理,连续种植玉米两年后采集土壤样品,采用湿筛法将团聚体分为>2、2～0.25、<0.25 mm共3个粒级,测定了土壤及团聚...

Effects of Different Straw-Returning Depths on Soil Aggregate Composition and Organic Carbon Distribution

In order to explore the effects of straw returning depths to the soil aggregates and organic carbon content in soil, the brown soil in Liaoning was used as the research object, and the field micro-area experiment was conducted to return the crushed straws to the field. A total of 5 treatments were set up, which were CK (no straw return to the field) and four straw returning depths of 0~10 cm, 10~20 cm, 20~30 cm, and 30~40 cm. Corn was planted and soil was taken two years after straw returning to the field. The wet sieve method was used to divide the aggregates into 3 particle sizes> 2 mm, 2 to 0.25 mm, and <0.25 mm, and the organic carbon content in the soil and the aggregates was determined. The results showed that: 1) The stability of soil aggregates and the content of large aggregates (>2 mm) increased significantly after straw returning to different soil depths(P<0.05). However, the degree of response of soil aggregates in different soil layers to straw returning was different. After returning straw to 0~10 cm and 30~40 cm, the MWD, GMD and R_0.25 increased greatly, the improvement on soil structure was better; 2) The organic carbon content was reduced after crushed straw returning to 0~10 cm, 10~20 cm, 20~30 cm at one time two years later, and the organic carbon content was significantly improved after straw returning to 30~40 cm(P<0.05); 3) The input of straw promoted the agglomeration process of the aggregates in the soil. After returning straw to different depths, the impact on the distribution of the organic carbon of the aggregates was different, but they all increased the content of organic carbon in large aggregates. The above results showed that straw returning to the field improve the soil structure and promote the conversion of organic carbon from small aggregates to large aggregates. Straw returning to 30~40 cm had a more obvious promotion effect on the agglomeration process of the soil, and the soil organic carbon content significantly increased. Therefore, 30~40 cm is a more reasonable straw returning depth.