灌水量对土壤水肥分布与春小麦水分利用效率的影响

Effect of Different Irrigation Quota on Water-Nutrient Distribution in Soil Profile and Water Use Efficiency of Spring Wheat

通过对春小麦不同灌水量土壤剖面水分和可溶性养分分布、农田实际蒸散量、作物水分利用效率及生物指标等的测定与计算,对沙坡头层次性土壤种植春小麦最适宜灌水量进行了研究。结果表明:(1)在春小麦拔节期及扬花期,以500 m3·hm-2、750 m3·hm-2及1 000 m3·hm-2水量灌溉,土壤剖面30~100 cm深度土壤含水量随灌水量的增加而明显增加。(2)拔节期3个灌溉水平土壤剖面可溶性养分含量分布的峰值均出现在 0~20 cm土层,但其浓度的下移随灌水量的增加而降低;扬花期土壤剖面可溶性养分含量的峰值随灌水量的增加而下移。在灌水量为500 m3·hm-2时可溶性养分浓度最高。(3)作物耗水量和农田实际蒸散量均随灌水量的增加而增加,春小麦的水分利用效率则随灌水量的增加而降低,与灌水量为500 m3·hm-2相比,灌水量为750 m3·hm-2及1 000 m3·hm-2时籽粒水分利用率分别降低83 33%和147 50%。可见,在该土壤上种植春小麦的最适宜灌水量为500 m3·hm-2,灌水量可保持在土壤田间持水量40%左右。

The optimal irrigation quota was estimated for spring wheat planted in Shapotou hiberarchy soil, through measuration of soil water and nutrient in soil profile, field evapotranspiration, water use efficiency and bio-indices of spring wheat under conditions of different irrigation quota. The results indicated that: (1) Soil water distributing depth increased obviously with the increase of irrigation quota in jointing and flowering stages of spring wheat; (2) The ranges of distributing peak values of soluble nutrient varied about 0~20 cm, with diminished concentrations along with the increasing of irrigation quota in the jointing stage of spring wheat. In flowering stage, with the increasing of irrigation quota, the depth of the distributing peak values of soluble nutrient moved downwards with maximal soluble nutrient concentration under the 500 m^(3)\5hm^(-2 )irrigation; (3) Consumed water of spring wheat and field actual evaportranspiration increased with the increasing of the irrigation quota, but the water use efficiency(WUE) changed inversely. Compared with the WUE under 500 m^(3)\5hm^(-2) irrigation quota, the WUE of grain under 750 m^(3)\5hm^(-2 )and (1 000) m^(3)\5hm^(-2) decreased 83\^33% and 147\^50%, respectively. So the optimal irrigation quot was about 500 m^(3)\5hm^(-2 )for planting spring wheat on this type soil, which would hold about 40% of field maximal capacity.