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| Soil moisture characteristic curve and model analysis of purple soil with residual plastic film |
| JIANG Wenjun, WANG Shiji*, LI Xian, LI Da |
| College of Engineering and Technology, Southwest University, Chongqing 400715, China |
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Abstract In order to explore the influence of residual plastic film on the soil-water characteristic curve of purple soil, 5 sets of residual plastic film amount(0,90,180,360,720 kg/hm2)were set. The soil-water characteristic curve of purple soil with residual plastic film during dehumidification was measured by pressure film apparatus. RETC software and statistical analysis were used to determine the optimal fitting model. The results show that the residue plastic film reduces the water holding capacity of purple soil, water capacity of purple soil and soil water supply capacity. There are significant diffe-rences in water content and water capacity between the treatment with residual plastic film and that with pure soil. When the soil water suction is 400kpa, the soil moisture of the 720 kg/hm2 residual plastic film treatment(LS5)is 86.36% of the non-residual plastic film treatment(LS1). As the amount of residual plastic film increases, the proportion of equivalent pore volume in the low suction section(mainly draining soil water from large pores)increases, while the proportion of equivalent pore volume in the high suction section(mainly draining soil water from medium and small pores)decreases. Compared with LS1 treatment, the macropores of LS5 treatment accounted for nearly 16% increase. Model fitness analysis shows that the best fitting model of the purple soil with residual plastic film is VGM(m,1/n), and the unsaturated hydraulic conductivity mode of the best model is Mualem mode. The results can provide a reference for the influence of residual plastic film on the migration of purple soil, water and salt in the southwestern area.
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Received: 06 December 2020
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