石羊河流域农田休闲期耗水规律研究

通过微型蒸渗器和diviner2000土壤水分测定仪测定了不同耕作及储水灌溉条件下农田休闲期土壤水分动态变化规律,并结合气象数据比较不同耕作方式和灌水处理的优越性,分析了休闲期不同耕作方式及储水灌溉措施对土壤水分及降水利用的影响。研究结果表明,春耕可减少农田表层土壤蒸发,保水效果较好;低定额储水灌溉既没有造成深层渗漏,且蒸发损失小;冬季大定额储水灌溉产生43.86 mm的深层渗漏和121.11mm的土壤水分蒸发,形成了水资源的无效流失;而春耕+免储水灌溉只产生54.41 mm水分损失,节水效果显著。土壤蒸发和深层渗漏产生的土壤水分损失大小顺序为:传统冬季储水灌溉>低定额储水灌溉>秋耕+免储水灌溉>春耕+免储水灌溉,低定额储水灌、秋耕+免储水灌溉、春耕+免储水灌溉处理土壤水分损失较对照分别减少53.44 mm、97.52 mm和110.56 mm(土面蒸发+深层渗漏)。石羊河流域春耕+免储水灌溉处理可有效减少休闲期水分损失,提高休闲期水分利用效率。

Farmland water consumption during fallow period in Shiyanghe River Basin

Water-storing irrigation, a widely applied irrigation method in Shiyanghe River Basin, stored redundant river or reservoir water in soil during fallow period through irrigation to provide water for the seedling growth in the next spring. Though lower evaporation in winter fallow period, the accumulative evaporation is still greater due to high evaporation during summer fallow period and high water-storing irrigation quotas. Given low water use efficiency and wasteful traditional irrigation, this paper put forward an alternative strategy for water-storing irrigation in Shiyanhe River Basin, west China. Different plough and irrigation methods were set to explore variation in soil water moisture and evaporation by using micro-lysimeter and driver 2000. Meteorological materials and other auxiliary data were also used to analyze the effects of different plough and irrigation practices on usage of soil water and rainfall. The study showed that no-tillage in autumn reduced surface soil evaporation with obvious water conservation effects. Low water-storing irrigation quotas prevented not only deep seepage, but also evaporative loss. High winter water-storing irrigation quotas caused 43.86 mm deep seepage and 121.11 mm soil moisture evaporation, laying the basis for wasteful utilization of the limited water resources. Spring plough without water-storing irrigation only caused 54.41 mm loss of water, whose water-saving effect was significant. Soil moisture loss via evaporation and deep seepage processes were in the order of traditional water-storing irrigation > low water-storing irrigation rate > autumn plough without water-storing irrigation > spring plough without water-storing irrigation. Compared with the control (CK), low rate water-storing irrigation, autumn plough without water-storing irrigation and spring plough without water-storing irrigation treatments reduced water loss by 53.44 mm, 97.52 mm and 110.56 mm, respectively. The experimental results indicated that spring plough without water-storing irrigation reduced water loss and improved water use efficiency in farmlands during fallow period in Shiyanghe River Basin.