蚯蚓改良水浇地土壤入渗性能及影响因素分析

Water Infiltration of Soil Affected by Earthworms

【目的】探究蚯蚓不同生态类型和密度对水浇地土壤水分入渗特征的影响。【方法】选取表栖型赤子爱胜蚓(Eisenia fetida)和深栖型参状远盲蚓(Amynthas aspergillum)为研究对象,以无蚯蚓土壤处理为对照,采用一维定水头土柱模拟试验,探究蚯蚓不同生态类型和密度(低密度4 g·kg^(-1),高密度8 g·kg^(-1))对土壤湿润锋、累积入渗量、入渗速率、含水率的影响及其与土壤性状的关系,并利用Philip模型和Kostiakov模型拟合分析土壤水分入渗规律。【结果】(1)在相同时间内,蚯蚓明显降低湿润锋推进距离、推进速率、累积入渗量及入渗速率,尤其是低密度参状远盲蚓影响最为显著(P<0.01),且低密度蚯蚓的入渗性能较高密度蚯蚓处理差。(2)各处理入渗结束后,土壤含水率存在差异,参状远盲蚓极显著提高土壤含水率(P<0.01),且低密度处理最佳。(3)蚯蚓通过改变土壤的理化性质来降低土壤水分的入渗性能,其中电导率(Electricity conductivity,EC)值、有效磷(Available phosphorus,AP)值和砂粒为土壤水分入渗的主要驱动因素。(4)与Philip模型拟合结果相比,采用Kostiakov模型拟合效果更适用,对参状远盲蚓处理土壤入渗过程的拟合精度(RMSE≤4.80 mm)更高,且参状远盲蚓极显著降低了累积入渗量衰减程度(P<0.01)。【结论】经赤子爱胜蚓和参状远盲蚓改良后的水浇地土壤(壤砂质地),水分入渗性能降低,但对水分的蓄持能力增加。在改良水浇地土壤时,添加低密度的参状远盲蚓有利于土壤持水。

【Objective】Effects of earthworms of different ecological classifications on water infiltration of the soil in which they inhabited were studied.【Method】Epigeic Eisenia fetida and endo-anecic Amynthas aspergillum were separately placed in soil containers to compare with one without earthworms.In a vertical one-dimensional stable water potential infiltration experimentation,the wetting front movement,accumulated infiltration,infiltration rate,and moisture content of the soil in the containers were monitored to analyze the correlation between soil properties and presence of the different types of earthworms in low-density at 4 g·kg^(-1) or high-density at 8 g·kg^(-1).The Philip and Kostiakov models were applied to mathematically describe the water infiltration function.【Result】①The existence of earthworms simultaneously reduced the advancing distance,advancing rate,cumulative infiltration amount,and infiltration rate of the water wetting front in the soil,especially in the case of low-density A.aspergillum(P<0.01).The effect was more significant under low-density than high-density of the earthworms.②Water retention of soil changed with the earthworm-induced water infiltration pattern which increased significantly by the low-density A.aspergillum treatment(P<0.01).③The major driving factors on soil that affected water infiltration attributed by the earthworms were electricity conductivity,available phosphorus,and sand.④Kostiakov model fitted the correlation between the soil water infiltration and the earthworm treatments more than Philip model did.A high fitting accuracy on RMSE≤4.80 mm was observed on the treatment by A.aspergillum.Moreover,A.aspergillum also significantly decreased the attenuation of cumulative water infiltration(P<0.01).【Conclusion】The water infiltration could be significantly lowered and moisture retention raised in a loamy sandy soil by the presence of E.fetida or A.aspergillum.It was conceivable that,at the density of 4 g·kg^(-1) of A.aspergillum,land of similar kind of soil could benefit from the improved water holding capacity as a result.