蚯蚓粪对土壤团聚体组成和入渗过程水分运移的影响

通过室内土壤团聚体组成分析试验和土柱一维垂直入渗试验,探究蚯蚓粪对土壤团聚体组成、抗水蚀稳定性以及入渗过程中水分运移特性的影响。结果表明:(1)蚯蚓粪可以有效降低土壤容重,增加0.25~2 mm粒级大团聚体的数量,分形维数D从2.84减小至2.65,减小了6.69%,显著提高了土壤团聚体抗水蚀稳定性;(2)施加比例为1/20时,可以显著增加湿润锋的运移距离,而后随着施加比例的增大,湿润锋距离有不同程度的减小,但均大于未施加蚯蚓粪的处理,且各处理下的湿润锋运移距离与入渗时间的关系均可用幂函数描述;(3)蚯蚓粪比例的增大可以显著提高累积入渗量和稳定阶段的入渗速率,当施加比例为1/3时,累积入渗量较对照组增大48.74%;其中Kostiakov-Lewis模型对入渗过程的模拟准确度最高,也更接近实测值。

Effects of Earthworm Casts on Soil Aggregate Composition and Water Transport During Infiltration

The effects of earthworm casts on soil aggregate composition, water-erosion stability and water transport characteristics during infiltration were studied by indoor soil aggregate composition analysis and one-dimensional soil vertical infiltration test. The results showed that:(1) The earthworm casts could effectively reduce the soil bulk density and increase the number of large aggregates of 0.25~2 mm. The fractal dimension D decreased from 2.84 to 2.65 by 6.69%, improving the water-resistant stability of soil aggregates significantly. (2) When the application ratio was 1/20, the migration distance of the wet front could be significantly increased, and then the wet front distance was reduced to some extent as the application ratio increased. But both were larger than the treatment without earthworm casts. The relationship between the wet front migration distance and the infiltration time under each treatment could be described by a power function. (3) The increase of the proportion of earthworm casts could significantly increase the cumulative infiltration amount and infiltration rate. When the ratio was 1/3 at the same time, the cumulative infiltration amount increased by 48.74% compared with the non-applied. The Kostiakov-Lewis model had the highest simulation accuracy, which simulated value was closer to the measured.