北京地区渗灌条件下冬小麦田间土壤水分动态及节水机理的研究

根据对渗灌条件下冬小麦田间土壤水分、冬小麦生长发育状况及产量的观测 ,研究了渗灌条件下冬小麦田间土壤水分动态及节水机理。试验结果表明 ,渗灌条件下田间土壤水分动态变化与灌溉、冬小麦生长发育状况及气象条件密切相关 ;渗灌用于冬小麦灌溉可以明显起到节约灌溉用水的作用 ,并有利于冬小麦的生长发育及产量形成。在冬小麦的整个生育期 ,采用渗灌比喷灌田间耗水量减少了44 4mm ,灌溉用水节约了1200m3/hm₂ ,而最终产量提高了714kg/hm₂ ,渗灌条件下作物水分利用效率为21 11kg/(hm₂·mm) ,比喷灌条件下高4 49kg/(hm₂·mm)。渗灌用于冬小麦灌溉的节水机理主要表现为两个方面 :①每次灌溉后 ,地表湿度较喷灌条件下要小得多 ,减小了土壤水分的无效物理蒸发 ;②渗灌利于冬小麦根系向地中供水层 (20～120cm )延伸 ,提高了冬小麦根系对灌溉供水层的水分利用

Studies on the soil-water dynamics of winter-wheat field and water-saving mechanisms under sub-irrigation condition in Beijing areas

Based on observations on field soil water,the growth and yields of winter wheat under sub irrigation condition,this paper studies the soil water dynamics of winter wheat field and water saving mechanisms.The analytical results showed that the field soil water dynamics of winter wheat field under sub irrigation condition had close correlations with irrigation,the growth of winter wheat and weather conditions.The results also showed that the consumption of irrigation water under sub irrigation condition was obviously reduced,and the sub irrigation was propitious to winter wheat growth and yield formation.During the whole growth period of winter wheat,the water consumed by sub irrigation was reduced by 44.4mm,a decrease of 1200 m3/ha of irrigation water than that by spray irrigation.The final yield increased by 714 kg/ha under sub irrigation condition.The WUE was 21.11kg/(ha·mm),which was 4.49 kg/(ha·mm) more than that under spray irrigation condition.The water saving mechanisms of sub irrigation for winter wheat are:(a)The humidity of soil surface (0～20cm) under sub irrigation is much less than that under spray irrigation during the whole growth period.So the non effective physical evaporation of soil water is greatly decreased under sub irrigation condition.(b)Under sub irrigation condition,because the soil surface (0～20cm) is drier,the wheat root systems are forced to extend to deep level to sop up water from medium soil levels (20～120cm),which have abundant soil water supplied by sub irrigation.As a result,the water utilization efficiency from the medium soil levels is increased.