秸秆还田对土壤微团聚体特征的影响

Effects of Straw Returning on Soil Micro-aggregate Characteristics

采用尼龙网袋法进行秸秆还田的原位模拟,比较不同秸秆还田量在不同深度下还田对土壤微团聚体组成及稳定性、微团聚体有机碳及腐殖酸组分的影响。试验设置秸秆还田量R0(0)、R1(0.44%)、R2(0.88%)、R3(1.32%)和0—15(S1),15—30(S2),30—45(S3)cm 3个不同还田深度交叉处理。结果表明:0.25~0.02mm的微团聚体为优势粒级,秸秆还田使各土层0.25~0.02,>0.25mm的团聚体含量增加,而0.02~0.002,<0.002mm的微团聚体含量减少,且各粒级含量的变化幅度均在S1层最大。不同秸秆量处理下不同土层,不同粒级的微团聚体的平均重量直径(MWD)较无秸秆还田均有所增加。同时,施用不同量秸秆能提高土壤各粒级微团聚体中有机碳及腐殖酸含量,且在同一土层中随粒级减小,有机碳及腐殖酸含量增加,而在不同土层内,有机碳及腐殖酸含量表现为S1>S2>S3。胡敏酸与富里酸比值对于不同土层,不同粒级的微团聚体则呈现不同的变化趋势。秸秆还田能促使土壤微团聚体向更大粒级的团聚体转化,有效增强土壤肥力的同时改善了土壤结构。

In order to compare the effects of different amounts with straw returning in different soil layers on the composition and stability of micro-aggregates,organic carbon and the humus components of micro-aggregates,situ-simulation experiment using nylon bag was conducted.In the experiment,four levels of R0(0),R1(0.44%),R2(0.88%),R3(1.32%)and three different returning depths of 0-15(S1),15-30(S2),30-45(S3)cm designd.The results showed that the micro-aggregates of 0.25~0.02 mm were the predominant class,and the aggregates of 0.25~0.02 and>0.25 mm content in the soil layers increased with the straw returning,while the aggregates of 0.02~0.002 and<0.002 mm were reduced,and the largest change among the particle content occured in the S1 layer.By incorporating the straw into the soil,the mean weight diameter(MWD)of different size micro-aggregates in different soil layers increased compared with those without straw.At the same time,different amounts of straw returning to the soil could increase the content of humic acid and fulvic acid in each fraction of micro-aggregates,and in the same soil layer,the content of organic carbon and humic acid increased with the decrease of particle size,while in different soil layers,the content of organic carbon and humic acid showed as S1>S2>S3.The ratio of humic acid to fulvic acid showed different trends for different micro-aggregates in different soil layers.As a result,it can be seen that straw returning can promote the transformation of soil micro-aggregates to larger aggregates,thus increase the soil fertility and improving the structure of the soil.