不同配套产品对涌泉根灌土壤湿润体特性影响

Effect of sleeve length on characteristics of wetted front during bubble-root irrigation

为了研究不同配套产品对涌泉根灌土壤入渗湿润体特性的影响,以黏壤土为例,采用PVC和PP棉2种材料,分别制作长度为10,15,20,25和30 cm的5个涌泉根灌配套套筒进行试验,分析涌泉根灌不同配套产品土壤入渗湿润锋随时间的运移关系.结果表明:2种材料的土壤表面水平湿润半径与时间的自然对数呈线性关系,表层土壤开始出现湿润的时间与套筒长度无关;2种材料的土壤最大水平湿润半径和湿润深度随套筒长度的增大而增大,并与时间呈幂函数关系,其中,PVC材料的水平和垂直向的幂指数分别为0.38和0.17;PP棉材料的水平向幂指数为0.40,垂直向幂指数随管长的增大而减小,并与管长呈线性关系.研究还建立了由表面水平湿润半径反演最大水平湿润半径和湿润深度的预测模型.经验证,模型预测精度较高.研究结果可为涌泉根灌不同配套产品的系统设计、田间布设间距和宽度等参数的确定提供参考.

In order to study the effect of sleeve length on the characteristics of wetted front in bubbleroot irrigation,a series of experiments were done to measure the wetted front of a clay loam soil formed during bubble-root irrigation in which five sleeve lengths( 10,15,20,25 and 30 cm) and two kind of sleeve materials,namely PVC and Polypropylene( PP) were used,respectively. The result showed that there is a linear relationship between the radius of wetted front on soil surface and logarithm of time for the two kinds of sleeves. The time when soil surface starts to be wetted is unrelated to the sleeve length. The radius and depth of wetted front in soils are increased with increasing sleeve length for both kinds of sleeves and a power function with time is exhibited. For the radius and depth of wetted front,their power indexes are 0. 38 and 0. 17 in the case of PVC sleeves. For PP sleeves,the power index of wetted front radius is 0. 40,the index of wetted front depth,however,is decreased with increasing depth and a linear relationship remains between the index and sleeve length. Further,prediction models were built for determining the maximum radius of wetted front on soil surface and the deepest depth of wetted front in soil from a known radius of wetted front on soil surface at a time instance. It was confirmed the accuracy of the models is satisfactory. The results can be useful for designing sleeves and determining space and width of ridge in a farm field.