秸秆覆盖夏玉米田棵间蒸发变化规律

Soil evaporation for summer maize under no- tillage with straw mulching

为了提高华北地区降雨的利用效率,采用覆盖免耕农艺措施,利用微型蒸发器并结合土壤含水率估算农田蒸散量ET,对秸秆覆盖夏玉米田棵间蒸发及棵间蒸发量占蒸散量的比值E/ET变化规律进行了研究.结果表明:全生育期玉米的棵间蒸发量覆盖处理比对照处理平均减少39.5%,差异具有统计学意义;棵间累积蒸发量与时间的关系变化趋势符合幂函数型,其拟合相关系数均达到0.99;覆盖处理E/ET为33.5%左右,对照处理E/ET为41%左右;秸秆覆盖与不覆盖处理的E/ET与叶面积指数的相关系数分别达到0.70和0.85左右.华北地区降雨总量基本与覆盖处理耗水量持平,但对照则出现阶段性缺水.该研究体现了覆盖免耕保墒技术的优势,为其在节水农业方面提供理论依据.

To improve the utilization efficiency of rainfall in North China,micro-lysimeters( MLS)were selected to measure soil evaporation( E) of summer maize with and without straw mulching and combined with soil moisture to estimate evapotranspiration( ET). The seasonal dynamics of E over the field and the ratio of E to ET were studied. The results show that soil evaporation of summer maize with straw mulching was reduced by an average of 39. 5% compared with CK,and there was significant difference. The change trend of accumulative evaporation capacity and time is in line with the power function model,and the fitting correlation coefficient reached to 0. 99. Straw mulched and no mulch treatment E / ET were about 33. 5% and 41%. The correlation coefficients of evapotranspiration of straw mulched and no mulch treatments under the condition of evaporation and leaf area index were0. 70 and 0. 85,respectively. The total rainfall in North China and the coverage of basic water con-sumption were about the same,but the control appeared stage water shortage. The study reflects the advantage of no-tillage with mulching agricultural water conservation technique,and offers a theoretical basis for water-saving agriculture.