中文摘要：

以北方高寒区典型城市哈尔滨市为研究区域，通过冬季大田试验（试验周期 2013-11-01—2014-04-30），设置自然无覆盖、覆盖秸秆厚度 5、10、15cm4 个处理，分别测定不同处理下 20、40、60、100、140、180cm深度土壤液态含水率以及气象数据，分析季节性冻融期秸秆覆盖对土壤水分变化特征的影响。研究结果表明：秸秆覆盖使0-60cm 土层内液态含水率增加或减小的时间拐点发生延迟，随着秸秆覆盖厚度的增加其延迟效果越明显，但土壤冻结期的延迟效果比冻土融化期明显；秸秆覆盖阻碍了冻土融化初期融雪水入渗，使自然无覆盖处理液态含水率在20、40、60cm 土壤深度出现短暂的峰值，而在冻土融化末期秸秆覆盖抑制了土壤水蒸发，使各秸秆覆盖处理液态含水率在 20、40、60cm 土壤深度又高于自然无覆盖。秸秆覆盖可有效平抑冻融期 0-60cm 土层土壤液态含水率的变化幅度，且随着土壤深度的增加其平抑效果具有减弱趋势；积雪融水和秸秆覆盖的双重作用能够有效增加土壤墒情，但其增墒能力随着土壤深度的增加而降低，不同秸秆覆盖处理对 0-60cm 土层的平均增墒能力由大到小排序依次为：15、10、5cm。

英文摘要：

In order to analyze the effect of straw mulching on changing characteristics of soil moisture during seasonal freeze-thaw period,Harbin City was selected as the objective study area,and soil liquid volumetric moisture content at different soil depths（ i. e. 20,40,60,100,140,180 cm） was measured in the field under straw mulching thicknesses of 5,10 and 15 cm in winter,and bare soil was taken as control. Meanwhile,the meteorological data was obtained from automatic meteorological station in the study area. The results showed that straw mulching thickness can retard the temporal inflection point of increasing or decreasing of soil volumetric moisture content between 0 cm and 60 cm soil depth,the retard effectiveness was more obvious with thicker straw mulching,and the retard effectiveness was more obvious in freezing period than that in thawing period. The snowmelt infiltration was prevented by the straw mulching at the beginning of thawing period,thus the liquid volumetric moisture content appeared temporary peak value at soil depth of 20,40 and 60 cm under the condition of bare soil. However,the liquid volumetric moisture content was lower in bare soil treatment than that in other three treatments due to straw mulching at the end of thawing period. The straw mulching could effectively adjust and remain the liquid volumetric moisture content at soil depth of 0 - 60 cm during freeze-thaw period,meanwhile,the adjustment effectiveness was weakened with the increase of soil depth. Both snowmelt and straw mulchingcan effectively increase soil moisture,but the increasing capability of soil moisture decreased with increasing soil depth. The order of the increasing capability of soil moisture at soil depth of 0 - 60 cm was15,10 and 5 cm thickness of mulching straw.