湖南烟稻轮作区土壤团聚体稳定性及其与碳氮比的关系

Stability of soil aggregate and its relationship with carbon nitrogen ratio in rice-tobacco rotation areas in Hunan province

【目的】明确湖南省烟稻轮作区不同土层土壤团聚体分布特征及其与碳氮比的关系。【方法】于2017年采集湖南郴州、衡阳和长沙烟区150个土壤样品,探讨了不同土层土壤团聚体的粒级含量、分布特征和稳定性,通过相关分析研究了土壤团聚体稳定性与碳氮比的关系。【结果】1)湖南省烟稻轮作区以>1 mm粒级土壤团聚体为主,百分比含量为64.47%;土壤碳氮比均值为9.66,变幅在3.69~14.06之间。各粒级土壤团聚体含量从高到低依次为>1 mm、0.5~1 mm、0.25~0.5 mm、<0.053 mm、0.053~0.25 mm。不同土层土壤团聚体平均重量直径(MWD)、几何平均直径(GMD)、水稳性大团聚体(R0.25)和分形维数(FD)呈显著差异;不同烟稻轮作区间变化趋势基本一致,随土层深度的增加,MWD、GMD和R0.25呈下降趋势,FD呈上升趋势。2)土壤碳氮比与MWD、GWD和R0.25呈显著正相关关系,与分形维数FD呈显著负相关关系,回归方程为y=2.89-0.02x(r2=0.57)。【结论】湖南烟稻轮作区土壤碳氮比与土壤团聚体具有紧密联系,土壤的碳氮比值越高则土壤团聚体就越稳定。因此,可以通过增施有机肥,控制氮肥,创造适宜的碳氮比,获得更多稳定性高的团聚体。

The objective of this study is to clarify the distribution characteristics of soil aggregates in different soil layers as well as its relationship with C/N in rice-tobacco rotation area of Hunan province.In 2017,150 soil samples were collected from Chenzhou,Hengyang and Changsha of Hunan province.The size fraction,distribution characteristics and stability of soil aggregates in different soil layers were discussed.The relationship between the soil aggregate stability and C/N was studied by correlation analysis.The results indicated that the rice-tobacco rotation area in Hunan province was dominated by soil aggregate with size of>1 mm,which accounted for 64.47%.The mean soil C/N was 9.66,and the variation range was 3.69~14.06.According to the size fraction from high to low,the aggregate content can be ranked as soil aggregate with size of>1 mm,soil aggregate with size of 0.5~1 mm,soil aggregate with size of 0.25~0.5 mm,soil aggregate with size of<0.053 mm,and soil aggregate with size of 0.053~0.25 mm.The mean weight diameter(MWD),geometric mean diameter(GMD),water stable aggregate(R0.25)and fractal dimension(FD)of soil aggregates in different soil layers were significantly different.With the increase of the depth of soil layer,MWD,GMD and R0.25 showed a decreasing trend,while FD showed an increasing trend.Correlation analysis showed that the soil C/N was significantly positively correlated with MWD,GWD and R0.25,while negatively correlated with FD,where the regression equation was y=2.89-0.02x(r2=0.57).Soil C/N is closely related to the soil aggregates in ricetobacco rotation area of Hunan province.The higher the C/N ratio of the soil,the more stable the soil aggregates.Therefore,it is possible to obtain more stable aggregates by adding organic fertilizer,controlling nitrogen fertilizer,and creating a suitable C/N ratio.