农膜残留对砂壤土和砂土水分入渗和蒸发的影响

通过室内试验设置5个不同残膜量(0、50、100、200、400 kg/hm~2)处理,研究不同残膜量对砂壤土和砂土水分入渗湿润锋、入渗速率、累积入渗量、土壤累积蒸发量和蒸发速率的影响,并评价了主要土壤入渗、蒸发模型在农膜残留土壤的适用性。结果表明:随着土壤中残膜量增多,砂壤土和砂土入渗速率变慢,土壤湿润锋运移相同距离所需时间均显著增加,其中运移30 cm时,砂壤土残膜量400 kg/hm~2处理(SL5)比无残膜处理(SL1)运移时间增加了27.56%;相同入渗时间内累积入渗量随残膜量增加均显著减小(P0.05),入渗结束后SL5处理比SL1处理累积入渗量减小了52.01 m L(23.12%);残膜量增加导致蒸发速率、累积蒸发量都显著减小(P0.05),蒸发结束后SL5处理比SL1处理累积蒸发量减小了30.63%,且不同残膜量对砂壤土的影响大于砂土。对4个土壤水分入渗及蒸发模型进行拟合,结果显示Kostiakov和Philip入渗模型均能较好模拟残膜条件下土壤水分入渗,其中Philip入渗模型拟合精度高于Kostiakov入渗模型,且对砂土中农膜残留下的土壤水分入渗模拟效果更好;Black蒸发模型随着残膜量增加拟合精度下降,而Rose蒸发模型受残膜量的影响较小,更适合于农膜残留土壤累积蒸发量估算。

Effects of Residual Plastic Film on Infiltration and Evaporation for Sandy Loam and Sandy Soil

The residual plastic film seriously affected the soil water infiltration and evaporation. Five residual plastic film treatments were conducted to study the effects of different residual plastic film amounts (0kg/hm2,50kg/hm2, 100kg/hm2, 200kg/hm2 and 400kg/hm2) on soil water infiltration and evaporation characteristics, and the infiltration front, infiltration rate, cumulative infiltration, cumulative evaporation and the evaporation rate were mainly studied based on the different residual plastic film quantities for sandy loam and sandy soil, and then the performance of main soil infiltration and evaporation model with residual plastic film was evaluated. The results showed that with the increase of residual plastic film quantity in the soil, the infiltration rates of sandy loam and sandy soil were decreased slowly, the time required for wetting front migration was increased significantly, and the sandy loam with 400kg/hm2 residual plastic film treatment (SL5) was increased by 27.56% compared with that of non residual plastic film treatment (SL1) at 30cm soil layer. In addition, the cumulative infiltration amount was significantly decreased (P<0.05) in the same infiltration time, and the cumulative infiltration amount of SL5 treatment was reduced by 52.01mL (23.12%) compared with SL1 at the end of infiltration. The evaporation rate and cumulative evaporation were significantly reduced (P<0.05) with the increase of residual plastic film quantity, the cumulative evaporation rate of SL5 treatment was 30.63% less than that of SL1 after evaporation, and the influence of different residual plastic film amounts on sandy loam was greater than that of sandy soil. The four major soil water infiltration and evaporation model were evaluated, it was showed that both Kostiakov and Philip infiltration models can well simulate the soil water infiltration for the soil with residual plastic film, but the Philip model had better performance than Kostiakov model, and had better adaptability for sandy soil with plastic film residue. The fitting accuracy of Black evaporation model was decreased with the increase of residual plastic film quantity, but the Rose evaporation model was less influenced by the amount of residual plastic film. So it can be concluded that the Rose evaporation model was more suitable for the plastic film residual soil cumulative evaporation estimation.