坡耕地黑土侵蚀沟演变对土壤结构及抗蚀性的影响

Effect of Black Soil Erosion Gully Evolution on Soil Structural Features and Anti-erodibility in Sloping Farmland

[目的]阐明侵蚀作用对黑土区坡耕地侵蚀沟土壤结构及抗蚀性的影响机制,为黑土区坡耕地侵蚀沟道演变提供基础数据和理论支撑。[方法]以哈尔滨市延寿县不同发育程度侵蚀沟为研究对象,对切沟的沟头、沟坡和沟底土壤进行系统采样,采用常规方法测定土壤的结构及抗蚀性特征。[结果](1)各沟道间WSA(10~0.25 mm水稳性团聚体含量)、MWD(水稳性团聚体平均重量直径)、GMD(水稳性团聚体几何平均直径)、分形维数均差异性显著(p<0.05)。随着侵蚀沟发育,MWD,GMD,分形维数在0—20 cm土层均呈〔CK(对照)>A_(1)(稳定沟)>A_(2)(半稳定沟前期)>A_(3)(半稳定沟后期)>A_(4)(发展沟)〕,为递减趋势;随着土层加深,大颗粒水稳性团聚体含量下降,结构恶化。(2)各沟道间分散系数、<0.05 mm分散率差异性显著(p<0.05)。二者在0—40 cm土层总体呈递增趋势;主成分分析表明0—20 cm与20—40 cm土层的抗蚀性综合得分表现为CK>A_(1)>A_(2)>A_(3)>A_(4)。[结论]侵蚀沟发育是造成黑土土壤结构与抗蚀性差异的主要原因,0—40 cm土层中土壤结构趋于恶化,土壤抗蚀性减弱,可蚀性增强。

[Objective]The aims of this study are to elucidate the mechanism of erosion gully on the soil structure and anti-erodibility in sloping farmland in black soil area,and to provide basic data and theoretical support for the evolution of erosion gullies in black soil area.[Methods]Erosion gullies of different development degrees in Yanshou County,Harbin City were used as the study object,soil samples were systematically collected from the head,slope and bottom of these gullies,the structural and anti-erodibility of the soil were analyzed using conventional methods.[Results](1)WSA,MWD,GMD,and fractal dimension were significantly different among the gullies(p<0.05).With the development of erosion gullies,MWD,GMD and fractal dimension all showed the decreasing trend,following the order:CK(control group)>A_(1)(stable gully)>A_(2)(early semi-stable gully)>A_(3)(later semi-stable gully)>A_(4)(developing gully)at the 0—20 cm layer.With the soil layer deepening,the large water-stable aggregates decreased and the structure deteriorated.(2)Dispersive coefficient and<0.05 mm dispersion rate were significantly different among the gullies(p<0.05),both show an overall increasing trend in the 0—40 cm layer.The principal component analysis showed that the composite score of anti-erodibility of 0—20 cm and 20—40 cm layers both showed the order:CK>A_(1)>A_(2)>A_(3)>A_(4).[Conclusion]Development of erosion gully is the main reason for the differences in soil structure and anti-erodibility in black soils.Soil structure tends to deteriorate in the 0—40 cm soil layer,while anti-erodibility weakens and erodibility increases.