典型黑土耕作区土壤结构对季节性冻融的响应

以东北典型黑土耕作区土壤为研究对象,通过对一季冻融交替后土壤团聚体、土壤楔入阻力、容重、孔隙度、饱和度、广义土壤结构指数等指标的测定和分析,对比研究了季节性冻融对黑土耕作土壤结构特征的影响.结果表明:季节性冻融加剧了黑土耕作区土壤风干团聚体的分散,但显著降低了水稳性团聚体的破坏率(P0.05),表现出促进其团聚的作用;季节性冻融后黑土土壤楔入阻力降低了15.45%;容重趋于一致,在1.10～1.11g.cm-3之间;固相比例持续增加,总孔隙度与毛管孔隙度均不同程度降低;土壤饱和度总体增加了13.06%,削弱了土壤潜在贮水能力.季节性冻融改善了耕作区的土壤结构,使之更适于耕作.虽然季节性冻融增强了土壤团聚体的抗蚀性,却削弱了土壤的抗冲性,增加了黑土水蚀发生的风险.

Responses of soil structure to seasonal freezing-thawing in a typical black soil cultivated region

Taking the soil in a typical black soil cultivated region as test object, this paper analyzed its aggregate size distribution, wedge resistance, bulk density, porosity, saturation degree, and generalized structure index after a seasonal freezing-thawing cycle, and evaluated the effects of the freezing-thawing cycle on the soil structural characters. The seasonal freezing-thawing cycle aggravated the disruption of air-dried aggregates, but strengthened the aggregation of water-stable aggregates and lowered their destruction rate. After the freezing-thawing cycle, soil wedge resistance decreased by 15.45%, and soil bulk density remained relatively constant from 1.10 to 1.11 g x cm(-3). The volume percent of soil solid phase increased, and soil total porosity and capillary porosity decreased to different degree. Soil saturation degree was improved by 13.06%, which in turn decreased the soil potential storage capacity. Seasonal freezing-thawing cycle improved the soil structure and soil arability and increased the erosion resistance of soil aggregates, but decreased the soil erosion resistance and increased the risk of the water erosion of black soil.