喷灌条件下不同茬次紫花苜蓿的耗水规律与灌溉制度

紫花苜蓿每年刈割多次,其不同茬次间的耗水规律与灌溉制度存在较大差异.在鄂尔多斯市鄂托克前旗牧区节水灌溉示范区进行紫花苜蓿中心支轴式喷灌灌溉试验,利用水量平衡原理计算得出喷灌条件下不同茬次紫花苜蓿耗水量,研究分析不同茬次紫花苜蓿耗水规律、产量、水分生产率和灌溉制度.结果表明:研究区第一、二和三茬紫花苜蓿耗水量总体呈现递增趋势,而不同茬次紫花苜蓿耗水强度呈现低-高-低变化规律;不同茬次紫花苜蓿产量差异明显,其中第二茬紫花苜蓿产量最高,第一茬产量次之,第三茬产量最低,对应不同茬次紫花苜蓿水分生产率也呈现相同的变化规律;一般年份紫花苜蓿喷灌条件下推荐灌溉制度为全生育期灌水7次,灌溉定额270~315 mm,其中第一茬灌水3次,灌溉定额120~135 mm,第二茬灌水2次,灌溉定额75~90 mm,第三茬灌水2次,灌溉定额75~90 mm.该研究成果对于多茬牧草灌溉决策和牧区节水灌溉工程设计具有一定意义.

Water consumption characteristic and irrigation schedule for different stubbles of alfalfa under sprinkler irrigation conditions

There are great differences in water consumption characteristic and irrigation schedule among different stubbles of alfalfa in a year. Irrigation experiments on alfalfa were conducted under sprinkler irrigation conditions in the water-saving irrigation demonstration field in pasture of Etuokeqin County, Ordos City. The water consumptions were calculated by using the principle of water balance, and the water consumption characteristic, yield, water productivity, and irrigation schedule for different stubbles were analysed. The results show that the water consumption exhibits an increasing trend for the first stubble to the third stubble, but the water consumption intensity is the maximum in the second stubble. The alfalfa yield varisd significantly across stubbles, among which the yield is the highest in the second stubble, followed by the first one, and the lowest in the third one. The corresponding water productivity demonstrates a similar variation pattern. Under sprinkler irrigation conditions, the recommended irrigation schedule is that there are 7 irrigations in the whole growth period of alfalfa with a quota of 270-315 mm, specially, there are 3 irrigations with a quota of 120-135 mm in the first stubble, followed 2 irrigations with a quota of 75-90 mm in the second stubble, and end up with 2 irrigations in a quota of 75-90 mm in the third stubble. The results have certain significance for decision-making of multi-stubble grass irrigation and design of water-saving irrigation projects in pasture.