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| Effect of sleeve length on characteristics of wetted front during bubble-root irrigation |
| Chen Junying1,2, Wu Pute1,2, Zhu Delan1, Zhang Zhitao1,3, Fan Xiaokang1 |
| 1.College of Water Resources and Architectural Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China; 2.Insititute of Soil and Water Conservation, CAS & MWR, Yangling, Shaanxi 712100, China; 3. Department of Biological and Agricultural Engineering, Texas A&M University, College Station, TX 77843, USA |
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Abstract In order to study the effect of sleeve length on the characteristics of wetted front in bubble-root 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 mo-dels 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.
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Received: 19 June 2012
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