轮作休耕模式对土壤团聚体及有机碳含量的影响

Effects of Crop Rotation and Fallow Patterns on Soil Aggregates and Organic Carbon Content

为探究轮作休耕模式对红壤坡耕地团聚体稳定性及有机碳含量的影响,通过田间试验设置了休闲地、玉米单作、玉米-豌豆-玉米和玉米-苕子-玉米4个处理,分析了不同种植模式下土壤团聚体稳定性及有机碳含量,结果表明:(1)不同种植模式下土壤机械稳定性和水稳定性团聚体组成均以≥0.25 mm粒径占比最高,机械稳定性团聚体占比在80.68%以上,水稳定性团聚体达到了77.05%以上,且≥0.25 mm团聚体所占比例大小顺序为:休闲地>玉米-豌豆-玉米>玉米-苕子-玉米>玉米单作。(2)根据不同团聚体稳定指数(MWD,GMD,R_(0.25)和PAD)显示,休闲地的团聚体稳定性最好,与玉米单作之间差异显著,且休闲地和玉米轮作两种模式下团聚体稳定性均优于玉米单作。(3)玉米单作土壤团聚体有机碳含量最低,玉米轮作和休闲地能显著提高有机碳含量,并且玉米-苕子-玉米轮作效果最优;≥0.25 mm粒径范围的团聚体储存的有机碳含量最高。(4)通过对土壤水稳性团聚体稳定指数与有机碳含量的相关性分析表明,4个不同团聚体稳定指数与有机碳含量都呈极显著正相关关系,与R_(0.25)相关程度最高。研究结果可为试验区域坡耕地水土流失防治提供理论依据。

In order to explore the effect of crop rotation and fallow patterns on the aggregate stability and organic carbon content of red soil sloping farmland,we set up four treatments of fallow land,maize monocropping,maize-pea-maize and maize-vetch-maize through field experiments.The soil aggregate stability and organic carbon content under different planting patterns were analyzed.The results show that:(1)the soil mechanical stability and water stability under different planting patterns have the highest proportion of soil aggregates with a size of≥0.25 mm;mechanical stability aggregates account for more than 80.68%,water-stable aggregates reach to more than 77.05%,and the proportion of≥0.25 mm aggregates decrease in the order:fallow land>maize-peas-maize>maize-vetch-maize>maize monocropping;(2)according to different aggregate stability indexes(MWD,GMD,R_(0.25) and PAD),the aggregate stability of fallow land is the best,which is significantly different from maize monocropping,in addition,the stability of aggregate in both fallow land and maize rotation is better than that in the maize monocropping;(3)soil aggregates in maize monocropping have the lowest organic carbon content;maize rotation and fallow land can significantly increase organic carbon content,and the effect of maize-vetch-maize rotation is the best;aggregates with size range of≥0.25 mm can store the highest carbon content;(4)the analysis of the correlation between the soil water-stable aggregate stability index and the organic carbon content shows that the four different aggregate stability indexes have a positive significant correlation with the organic carbon content,and have the highest correlation with R_(0.25).These results of this study can provide a theoretical basis for the prevention and control of soil erosion on sloping farmland in the test area.