Effects of water infiltration and storage in cultivated soil on surface irrigation

摘要

a- The irrigation functions, phases, coefficients, and soil water storage and distribution have been evaluated in a grape field. Empirical power form equations were obtained for measured advance and recession times and infiltration depths along the furrows and border lengths during the irrigation stages of advance, storage, depletion and recession. a- We concluded that the short irrigation interval using furrow irrigation with little amount of water (wet treatment) was better than far interval with large amount of water per irrigation (dry treatment). Grape yield was highly decreased due to increasing irrigation interval and insignificantly affected by increasing amount of water per irrigation. a- The partially-wetted furrow irrigation had greater water-efficiency and grape yield than dry furrow treatment and traditional border irrigation. The wet treatment achieved 11.9kg/m3 water use efficiency (WUE) with 11.9% deep seepage percentage compared with 9.9kg/m3 WUE with 18.9% deep seepage under furrow dry treatment. Surface irrigation analysis and design require the knowledge of the variation of the cumulative infiltration water Z (L) (per unit area) into the soil as a function of the infiltration time t (T). The purpose of this study is to evaluate water infiltration and storage under surface irrigation in an alluvial clay soil cultivated with grape yield, and to determine if partially wetted furrow irrigation has more efficient water storage and infiltration than traditional border irrigation. The two irrigation components considered were wet (WT) and dry (DT) treatments, at which water applied when available soil water reached 65% and 50%, and the traditional border irrigation control. Empirical power form equations were obtained for measured advance and recession times along the furrow length during the irrigation stages of advance, storage, depletion and recession. The infiltration (cumulative depth, Z and rate, I) was functioned to opportunity time (t o ) in minute for WT and DT treatments as: Z WT =0.528 t o 0.6, Z DT =1.2 t o 0.501, I WT =19 t o a degree 0.4, and I DT =36 t o a degree 0.498. The irrigation efficiency and soil water distribution have been evaluated using linear distribution and relative schedule depth. Coefficient of variation (CV) was 5.2 and 9.5% for WT and DT under furrow irrigation system comparing with 7.8% in border, respectively. Water was deeply percolated as 11.88 and 19.2% for wet and dry furrow treatments, respectively, compared with 12.8% for control, with no deficit in the irrigated area. Partially wetted furrow irrigation had greater water-efficiency and grape yield than both dry furrow and traditional border irrigations, where application efficiency achieved as 88.1% for wet furrow irrigation that achieved high grape fruit yield (30.71Mg/ha) and water use efficiency 11.9kg/m3.