豫北冬小麦、夏玉米多年需灌水次数及典型 生育期需灌水分析

研究气候变化情景下豫北地区农业需灌水次数的变化情况,可为当地灌溉以及保证农业可持续发展提供参考。本文分析处理近63 a(1951—2013年)气象数据和新乡七里营站点土壤数据,结合作物生长参数,利用降水、灌溉、作物蒸散发与土壤水分之间变化关系,建立干旱灌水指数模型。此模型中干旱灌水指数(DII)分布在-1,1]之间,小于0时即干旱需灌水。在现有冬小麦-夏玉米种植制度下,利用干旱灌水指数模型计算多年需干旱灌水指数,并进一步得到灌水次数。选择冬小麦生长季分别为湿润(1985—1986年)、正常(2004—2005年)、干旱(1983—1984年)的3个典型实际代表年度,夏玉米生长季分别为湿润(2003年)、正常(1993年)、干旱(2009年)的3个典型实际代表年,计算了不同代表年冬小麦、夏玉米作物需水情况。进一步计算得到了冬小麦、夏玉米在典型湿润、正常、干旱3个不同代表年的干旱灌水指数,并进行了有无灌水的干旱情况分析。结果表明:近63 a冬小麦-夏玉米系统每年需灌水2~7次不等,平均需灌水5.1次。冬小麦和夏玉米湿润、正常、干旱3个代表年蒸散发量(ETC)分别为489.4 mm、551.4 mm、481.7 mm和466.1 mm、477.8 mm、529.3 mm。在无灌水条件下典型代表年内,冬小麦、夏玉米都会遭遇不同程度干旱,典型湿润、正常、干旱代表年冬小麦分别灌水2次、3次、4次,夏玉米分别需灌水1次、2次、3次后,基本可以消除干旱对其正常生长影响。综上,通过干旱灌水指数来量化需灌溉次数是可行的。气候变化情景下,近10年(2003—2013年)需灌水频次变化大,年际间干旱事件频发,更好的科学灌溉管理可减少干旱对作物的影响。

Multi-years required irrigation times of winter wheat and summer maize and analysis of irrigation in representative growing seasons in northern Henan

With globe climate changing, the intensifying uncertainty of precipitation induced inconsistency of irrigation schedule in different years and at different growth stages of crops. Therefore, conventional irrigation schedule fails to guide irrigation activities precisely. It becomes increasingly important for irrigation management and sustainable development of agriculture to explore changes of agricultural irrigation requirement against the background of frequently extreme meteorology events. In this paper, meteorological data of the recent 63 years (from 1951 to 2013) and soil data in Xinxiang City of northern Henan, as well as crop growth parameters were used to establish the model of drought irrigation index according to the relationships among precipitation, irrigation, evapotranspiration (ETC) and available soil water. In the model, drought irrigation index (DII) was 1, 1]. Once DII was less than 0, irrigation was necessary. On the basis of winter wheat-summer maize planting schedule in the study area, the model was used to calculate multi-year DIIs for the recent 63 years. Consequently, annual irrigation times potentially meeting the agricultural requirement were obtained based on DIIs from 1951 to 2013. Three representative growing seasons of winter wheat and summer maize were selected as wet (19851986 for winter wheat, 2003 for summer maize), normal (20042005 for winter wheat, 1993 for summer maize) and dry (19831984 for winter wheat, 2009 for summer maize) growing seasons. Water requirement of two crops in different growing seasons were calculated, and DIIs in there representative growing seasons of winter wheat and summer maize were calculated too under the conditions with and without irrigation. The results showed that required annual irrigation times ranged from 2 to 7 with an average of 5.1 in recently 63 years in norther Henan Province. ETC of winter wheat and summer maize in wet, normal, dry growing seasons were 489.4 mm, 551.4 mm, 481.7 mm and 466.1 mm, 477.8 mm, 529.3 mm, respectively. Under the condition without irrigation, the winter wheat and summer maize suffered varying degrees of drought in typical growing seasons. Winter wheat respectively needed 2, 3, and 4 times irrigation, while summer maize respectively needed 1, 2 and 3 times irrigation in wet, normal and dry actual representative growing seasons. Even if in wet growth seasons of summer maize, irrigation also required during periods with high ETC but no timely rainfall. DII could guide irrigation well according to the relationship among meteorology, available soil water and crop growth information. It was practicable to decide irrigation time with DII. With climate changing from 2003 to 2013, the frequency of irrigation times fluctuated more remarkable, and interannual drought stress took place more frequently than the past 63 years. Scientific and reasonable irrigation managements should be worked out in order to reduce the influence of drought stress on crop growth.