万荣县麦田土壤干旱研究

Study of soil drought of winter wheat field in Wanrong

万荣县气象局1964—2008年0～100 cm各旬旱地麦田土壤湿度资料分析表明,小麦生育期的耕作层土壤相对湿度有下降趋势,特别是拔节抽穗期土壤相对湿度下降4.9%.10a-1,作物旱情指标Kd和作物水分亏缺率G也显示拔节抽穗期干旱化明显。另外,冬前和越冬期分蘖数增大。土壤干旱的综合原因是降水量(特别是夏季)减少、冬前和越冬期作物系数增大和四月日照不显著增多引起的参考作物蒸散增加。拔节抽穗期有明显的干旱化趋势。

The soil moisture change of winter wheat field in Wanrong is analyzed using the observed data from Wanrong meteorological station during the period of 1964—2008.soil relative humidity of plough horizon in developmental stages showed a declining trend,especially in elongation heading period at rate of-4.9%/10a,the crop drought index Kd and the crop water deficit index G in elongation heading period also show soil drought significantly,and the increasing of tiller number in sowing-wintering and wintering-reviving lead to increasing crop coefficient.the soil drought is caused by precipitation（especially in summer） reduction,crop coefficient increased before and during wintering,the increasing reference crop evapotranspiration is caused by no-significant sunshine increase in April.All these reason leading to significant trend of soil drought in elongation heading period.