干湿交替对重构土壤物理性质的影响

Effect of Drying-Wetting Alternations on the Physical Properties of Reconstructed Soils

    摘要
  • 摘要:
    目的 探究干湿交替过程对质地重构土壤物理性质的影响，为毛乌素沙地改良农田提供技术支撑。
    方法 选用毛乌素西北部的红黄土、砒砂岩、砂黄土，以设定容重和混合比例的4个室内土柱：砒砂岩、红黄土、砒－砂重构土、红－砂重构土为研究对象，在第0、1、3、5、8、12、15次干湿交替后定土壤容重、土壤饱和导水率和团聚体稳定性的变化，分析质地重构土壤的物理性质对干湿交替次数的响应。
    结果 第一次干湿交替后，4种土壤的容重均显著降低（P < 0.05），而土壤饱和导水率均显著升高（P < 0.05）；之后，随着干湿交替次数的增加，土壤容重有小幅增加并逐渐趋于稳定，而土壤饱和导水率逐渐减小并趋于稳定；干湿交替对砒－砂和红－砂重构土壤物理性质的影响分别小于砒砂岩和红黄土。此外，干湿交替次数与土壤团聚体破碎率呈正相关，这表明干湿交替有利于4种土壤大团聚体的形成，并且机械稳定性大团聚体增加的速率显著高于水稳性大团聚体。
    结论 相比于自然土壤，重构土壤由于降低砂粒含量从而显著减少干湿交替过程对土壤物理性质的影响，能保持土壤物理性质的稳定。两种重构土中，砒－砂重构土效果优于红－砂重构土，说明该重构类型可作为毛乌素沙地复垦土壤的优选方案来使用。

     

    Abstract:
    Objective The aims were to explore the effects of drying-wetting alternations on the physical properties of texture-reconstructed soils and to provide technical support for reclamation in Mu Us Sandy Land.
    Method The red loess, Pisha sandstone and sandy loess in the northwest of Mu Us Sandy Land were selected. Four indoor soil columns with the specific bulk density and mixing ratio: Pisha sandstone, red loess, Pisha-sand reconstructed soil and red-sand reconstructed soil were used as the research objects. The changes of soil bulk density, soil saturated hydraulic conductivity and aggregate stability were measured at the 0th, 1st, 3rd, 5th, 8th, 12th and 15th dry-wet alternations, and the responses of physical properties for the texture reconstructed soils to dry-wet alternation times were analyzed.
    Result After the first dry-wet alternation, the bulk density of the four soils decreased significantly (P < 0.05), while the soil saturated hydraulic conductivity increased significantly (P < 0.05). After that, with the increase of the number of wet-dry cycles, the soil bulk density increased slightly and gradually stabilized, while the soil saturated hydraulic conductivity gradually decreased and stabilized. In addition, the number of dry-wet alternations were positively correlated with the breakage rate of soil aggregates, which indicated that dry-wet alternation was beneficial to the formation of four soil macroaggregates, and the increase rate of mechanically stable macroaggregates was significantly higher than that of water-stable macroaggregates.
    Conclusion Compared with the natural soil, the reconstructed soil can significantly reduce the effect of drying-wetting alternations on soil physical properties, so as to maintain the stability of soil physical properties. Among the two reconstructed soils, the effect of Pishasand reconstructed soil is better than that of red-sand reconstructed soil, indicating that this type of reconstruction can be used as the optimal scheme for reclamation of soil in Mu Us Sandy Land.

     

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