黑土区坡耕地侵蚀沟演变对土壤粒径分布及蓄水性的影响

Effects of Erosion Gully Evolution on Particle Size Distribution and Water Storage Properties in Sloping Cropland of a Black Soil Area

[目的]研究侵蚀作用对黑土区坡耕地侵蚀沟表层土壤的影响,为该区土壤资源合理运用和区域水土流失治理工作提供理论支持。[方法]以黑龙江省哈尔滨市延寿县不同发育程度侵蚀沟为研究对象,对切沟沟头的沟坡和沟底土壤的粒径分布及蓄水性进行定量描述。[结果]①不同深度处土壤容重、最大吸持贮水量、最大滞留水量、总库容、死库容、最大有效库容差异显著(p<0.05)。随土层加深,土壤容重增大,贮水量、持水性、有效水分下降。各层最大吸持贮水量占饱和贮水量均约90%,有效水分利用率分别为44.79%和41.87%,侵蚀沟发育对土壤有效水分影响明显。②入渗特征总体表现为:初始入渗速率>30 min入渗速率>稳定入渗速率,3者在不同编号沟道的A 2—A 4间随土层的加深,入渗性能下降。在20—40 cm层A 1—A 4的入渗特征均表现为:CK(对照)>A 1>A 4>A 2>A 3,呈先下降后上升趋势。随着侵蚀沟的发育,土壤入渗性先下降后上升。③侵蚀沟的发育是黏粒含量变化的主要原因,黏粒所占比例在0—40 cm层呈先增大,后减小趋势;砂粒所占比例在0—20 cm土层先减小,后增大,呈粗骨化趋势。④土壤退化指数在0—20 cm层表现为:A 1>A 2>A 3>A 4。随侵蚀沟的发育,土壤退化程度加剧,A 4土壤退化最为严重。[结论]不同深度的土壤剖面差异是造成黑土土壤物理性质差异的主要原因,随着侵蚀沟的发育,0—20 cm层土壤蓄水性能减弱,土壤退化严重。

[Objective]The effects of erosion on the surface soil of erosion gullies in sloping cropland soils in a black soil area were studied in order to provide theoretical support for the rational utilization of soil resources and regional soil and water conservation work in black soil areas.[Methods]The study was conducted on erosion gullies with different degrees of development in Yanshou County,Harbin City,Heilongjiang Provicne.Particle size distribution and water storage properties of soil on the slope,at the bottom of the gullies and at the head of the gullies were quantitatively described.[Results]①Soil bulk density,maximum water-storage capacity,maximum water-retention capacity,total storage capacity,dead storage capacity,and maximum effective storage capacity at different depths were significantly different(p<0.05).As soil depth increased,soil bulk density also increased,and water-storage,water-retention,and effective water storage capacity decreased.Each layer had a maximum water-storage capacity of about 90%of its saturated capacity,and the effective water utilization rates were 44.79%and 41.87%,respectively.The development of erosion gullies had a clear influence on effective soil water.②The infiltration characteristics generally showed that the initial infiltration rate>the 30-minute infiltration rate>the stable infiltration rate.As soil depth increased,the infiltration characteristics of the three indicators decreased between gully A 2 and A 4 for different erosion degree gullies.In the 20—40 cm layer,the infiltration characteristics of gully A 1 to A 4 followed the order of CK(control group)>gully A 1>gully A 4>gully A 2>gully A 3.Infiltration initially declined and then increased.With the development of the erosion gully,soil infiltration decreased and then increased.③The development of erosion gullies was the main reason for the change in clay content.The percentage of clay in the 0—40 cm layer tended to increase first and then decrease.The percentage of sand in the 0—20 cm layer tended to decrease first and then increase,showing a trend toward increased coarseness.④The soil degradation index followed the order of gully A 1>gully A 2>gully A 3>gully A 4 in the 0—20 cm layer.Soil degradation increased with the development of erosion gullies.Soil degradation was most severe in gully A 4.[Conclusion]The differences in soil profiles was the main reason for the differences in physical properties of black soil.Soil water-holding capacity in the 0—20 cm layer was weakened and soil degradation became severe as erosion gullies developed.