西藏地区春青稞耗水特征及适宜灌溉制度探讨

以中科院拉萨高原生态试验站为依托,通过开展春青稞生长与土壤水分定位观测实验,利用SHAW模型实现对春青稞农田蒸散发与土壤水深层渗漏与补给过程模拟,分析了春青稞的耗水特征,并对其适宜的灌溉制度进行了初步探讨:①春青稞生长期间,耗水450 mm左右,其中,分蘖—拔节、拔节—抽穗、抽穗—蜡熟这3个阶段是春青稞的耗水旺期,耗水量占整个生长期的72%。把握住该时期的水分供应,对提高作物产量十分重要。②在春青稞的需水关键期降水量仅能满足作物需水的58%,必须补充人工灌溉;但现行的灌溉制度由于灌溉量较大,不仅加大土壤蒸发,更造成较大的深层渗漏。③在播种—出苗、拔节—抽穗期分别灌溉50 mm,抽穗—蜡熟期灌溉60 mm,共减少灌溉用水125 mm后,深层渗漏减少了81%(131 mm);深层土壤水向上补给量增加了55%(44 mm)。节水灌溉不仅减少了土壤蒸发与深层渗漏也促使深层土壤水向上补给根系层,应该大力推广这一灌溉制度。

Study on Water Consumption of Spring Naked Barley Land and Suitable Irrigation System in Tibet

Based on the crop growth and soil water content observed experiments in Lhasa Plateau Ecosystem Research Station, this paper used SHAW model to investigate the characteristics of water consumption and soil water deep percolation and deep soil water recharge of spring naked barley land. Then, the paper also discussed the prospective of the suitable irrigation scheduling according to the comparison of water consumption and water deep percolation and deep soil water recharge under sufficient irrigation and nonsufficient irrigation. Major results are reported as follows:1) Total water consumption of spring naked barley is estimated to be 450 mm. Hereinto, tillering to shooting, shooting to tasseling and tasseling to grain filling are the dominating water consumed stages, the water consumption of which accounts for 72%. So,it is important to ensure water supply in this stage.2) In the dominating water consumed stages, precipitation only covers 58% of the water requirement of spring naked barley, so, supplying irrigation is necessary. But, the existing irrigation scheduling enhances soil water evaporation and causes huge deep percolation.3) If the amount of 50 mm water is irrigated in the planting-emerging and shooting-tasseling stages respectively and 60 mm in the tasseling-grain filling stage, the total irrigation amount reduces 125 mm, deep percolation will reduce 81% (131 mm) and deep soil water recharge will increase 55% (44 mm). The prospective less irrigation would reduce deep percolation greatly and promote water recharge from deeper soil layer. Therefore, the prospective less irrigation should be extended.