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.