植物混掺土壤水分特征曲线及拟合模型分析

Soil-water Characteristic Curves of Soil with Plant Additive and Analyses of the Fitting Models

为探求植物混掺对土壤持水能力的影响,通过测定不同土壤容重、不同混掺物及混掺比例条件下的土壤水分特征曲线,分析植物混掺物对土壤持水能力的影响,并利用RETC软件结合统计分析确定不同处理的模型适宜性。结果表明,相同土壤水吸力下,添加植物混掺物处理的土壤含水率均高于纯土处理;添加3%植物混掺物的处理中,玉米叶的保水效果优于玉米芯,而添加1%植物混掺物的处理中两者差异较小;低吸力阶段,混掺物的添加减少了土壤中大孔隙的比例,而在中高吸力阶段,混掺物的添加增大了土壤中小孔隙的比例,进而提高土体的持水能力。模型适宜性分析结果表明,各处理最优模型的非饱和导水率模式均为Mualem模型;土壤容重为1.35g/cm3和1.40g/cm3,混掺比例为1%和3%的玉米叶处理时,最优模型分别为VGM(m,1/n)和VGM(m,n),混掺比例为1%和3%的玉米芯处理时,最优模型分别为BCM和VGM(m,1/n)。

With the aim to explore the influence of plant additive on soil water holding capacity, the soil-water characteristic curves under different soil bulk density, different plant additives and different additive proportions were measured, and the influences of plant additive on the soil water-holding capacity under the conditions mentioned above were analyzed. Then, the soil-water characteristic curves were fitted by using the models of RETC software,and the parameters of the models and the model suitability were determined. The results show that under the same soil water suction, the soil water contents of the treatments with plant additive are higher than that of pure soil; the treatment with 3% maize leaf plant additive has better water conservation capability than the treatment with 3% maize-cob, but the treatments with 1% plant additive have little difference. In the low suction stage, the mixing plant additive reduces the proportion of large pores in the soil; while at the higher suction stage, the plant additive increases the small pores proportion of soil, thereby improves the soil water-holding capacity. The analysis results of model suitability with models of RETC software show that the optimal model of unsaturated hydraulic conductivity is fitting Mualem model. The optimal models of the treatments with 1.35g/cm^3 and 1.40g/cm^3 soil bulk density are VGM（m,1/n） and VGM（m,n）, respectively, with 1% and 3% maize leaf additive, while those are BCM and GM（m,1/n）, respectively, with 1% and 3% maize-cob additive.