基于氢氧稳定同位素的华北农田夏玉米耗水规律研究

农作物耗水规律的研究对提高农业用水效率,缓解我国华北地区的水资源短缺现状具有重要意义。论文基于水文监测与氢氧稳定同位素方法,以山西省运城市董村农场为例,研究了夏玉米在不同生长期的根系吸水深度变化,以及农田灌溉条件下SPAC系统的水分通量。研究结果表明,夏玉米拔节期、开花期和成熟期的主要根系吸水深度分别为0~20 cm(96%~99%)、20~50 cm(58%~85%)、0~20 cm(69%~76%),在整个生长期内存在着先由浅变深,后由深变浅的规律;夏玉米漫灌后,蒸腾量占蒸散发量的71.3%,深层入渗损失量占到灌溉水量的43.3%,灌溉水的利用率仅为40.4%,应采取措施减小深层入渗量以提高灌溉水利用率。

Study on Water Consumption Law of Summer Corn in North China Using Deuterium and Oxygen-18 Isotopes

Study on the water consumption of crops is vital to the improvement of the utilization efficiency of agricultural water, and alleviation of water shortage in North China. In this paper, the Dongcun farm in Yuncheng, Shanxi Province is taken as an example to estimate the depth of root water uptake in growing stages and the water flux in SPAC system after irrigation for the summer corn. Precipitation, irrigation water, soil water, groundwater and stem water were sampled for stable isotopes analyses supported by hydrological observations. Both direct inference of hydrogen and oxygen isotopes between stem water and soil water profile and multiple-source mass balance assessment were applied to estimate the main depths of root water uptake of crops in different growing seasons. The results show that summer corn mainly uses the soil water from 0-20 cm layer (96%-99%) in jointing stage, 20-50 cm layer (58%-85%) in flowering stage, and 0-20 cm layer (69%-76%) in full ripe stage, which means the main depth of root water uptake goes downwards at first, then upwards in the whole growing stages. By the method of soil water balance and isotope mass balance, the water flux in SPAC system after irrigation for the summer corn is calculated: After the irrigation on August 11th, 2008 for summer corn (flowering stage, 90 mm, flood irrigation), the deep infiltration takes up as much as 43.3%, and transpiration of corn accounts for 71.3% of the total evapotranspiration, so the irrigation water use efficiency is only 40.4%. The existing irrigation efficiency is low in the study area, and measures should be taken to reduce the deep percolation after irrigation. Our experiments are carried out under certain conditions, and the results will not be common, but they can give more insight into water consumption of the summer corn in the study area and help improve the existing irrigation system in North China.