农田秸秆覆盖条件下降雪融化过程研究

Process of Snow Thawing Mulched with Straw in Cropland

秸秆覆盖条件下雪的融化过程是季节性冻融区融雪期坡面侵蚀防治和土壤墒情改善的理论基础。为了解决在春季融雪时出现大面积融雪径流而造成的侵蚀发生,以东北地区冬季垄作农田为试验地点,以6个水平的秸秆覆盖处理和留茬为研究对象,即裸地(S0)、0.5kg·m-2(S0.5)、1kg·m-2(S1.0)、1.5kg·m-2(S1.5)、2.5kg·m-2(S2.5)、3.5kg·m-2(S3.5)和留茬(SL),通过对耕地布设不同秸秆覆盖量,探究和分析秸秆覆盖量对降雪融化过程的影响。研究结果表明:S1.5在融雪初期最先发生融化,SL融雪速率峰值最大,融雪最后均为S2.5最先融通;融化过程中,高覆盖处理的S1.5、S2.5和S3.5融雪累积面积均呈缓慢增加的趋势,且始终高于低覆盖处理的S0、S0.5、S1.0,SL在融雪中期出现骤增,随后累积面积超过低覆盖处理;气温与融雪累积面积相关性较高,各处理表现为S2.5>S3.5>S1.5>SL>S0>S1.0>S0.5;反辐射与融雪速率相关性较高,表现为与高覆盖各处理的相关性在融雪前期较高,而与低覆盖各处理的相关性在融雪后期相对较高。该研究结果可为季节性冻融区冬春季土壤墒情诊断和灌溉提供合理技术参数与依据。

Snow thawing process under straw mulching is the theoretical basis of erosion prevention and control of soil moisturein snowmelt slope. To solve erosion by large snowmelt runoff in spring, this study selected the winter ridge cropland as test sitesin Northeast China. Six levels of straw covered treatments （stubblebare ground, （S0）,0.5（S0.5）,1（S1.0）,1.5（S1.5）,2.5（S2.5）,3.5（S3.5）kg.m-2 andleave stubble （SL） were selected to analyze the impact of straw coverage on snow thawing process. The results showed that S1.5was the first to thaw in the early stage of melting snow. SL showed the largest thawing rate,and snowmelt of S2.5 finished first.During the thawing process, thesnow accumulation area of S1.5, S2.5 and S3.5 showed slowly increasing trend and was always higherthan the low coverage treatments （S0, S0.5, S1.0）. SL appeared surge in the middle of snowmelt period, then higher than that in thearea of low coverage. Temperatures and snow accumulation area showed high correlation, different treatments were following theorder： S2.5 〉S3.5 〉S1.5 〉SL 〉S0 〉S1.0 〉S0.5. The rate of anti -radiation associated with snowmelt was high, which correlation betweenreflectivity and high coverage of each treatment was higher during the snow thawing period. While the correlation betweenreflectivity and low coverage was relatively high in the late of thawing snow. The results could provide reasonable technicalparameters and basis for seasonal freeze-thaw area in winter and spring soil moisture diagnosis and irrigation.