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以东北典型黑土区耕地土壤为研究对象,采用室内模拟冻融以及CT(Computerized tomography)扫描相结合的方法,通过大孔隙数目、平均面积、Feret直径以及成圆率4个指标的量化与分析,研究了冻融循环对不同深度范围土层(0~40 cm、40~80 cm、120~160 cm)土壤大孔隙特征的影响规律。结果表明:冻融循环没有对表层土壤大孔隙结构产生影响,却能够显著降低40~80 cm土层范围内平均大孔隙面积以及Feret直径,降幅分别为46.72%和17.32%(p<0.05),且以1~2 mm和≥5 mm的孔隙对冻融循环响应最为强烈,冻融循环后分别降低9.58%和42.19%(p<0.05)。研究结果不仅证明了黏化层滞水效应的可能,同时探明了黏化层孔隙结构对冻融循环的敏感性,由此印证了季节性冻融循环对黏化层抗蚀性的削弱以及黏化层的滞水效应是导致黑土区地表侵蚀与沟蚀的主要原因。
Taking arable soil in typical black soil area of northeast China as the research object, through the combination of indoor simulated freezing and thawing and CT (Computerized tomography) scanning, through the quantification and analysis of four indexes of macropore number, average area, Feret diameter and rounding rate, The effects of freeze-thaw cycles on the macroporosity characteristics of soils in different depth ranges (0-40 cm, 40-80 cm, 120-160 cm) were studied. The results showed that the freezing and thawing cycles did not affect the macropore structure of the topsoil, but significantly reduced the average macropore area and the Feret diameter in the 40-80 cm soil layer (46.72% and 17.32%, respectively, p <0.05) The pores with 1 ~ 2 mm and ≥5 mm had the strongest response to the freeze-thaw cycles, decreasing by 9.58% and 42.19% (p <0.05) after freezing and thawing cycles respectively. The research results not only proved the possibility of water stagnation effect of the adhesion layer, but also proved the sensitivity of the pore structure of the adhesive layer to the freeze-thaw cycle, thus confirming the weakening of the corrosion resistance of the adhesion layer by the seasonal freeze-thaw cycle The sticking layer’s water stagnation effect is the main reason of surface erosion and gully erosion in black soil area.