白膜和黑膜覆盖对黄绵土保水调温的效应

Effects of film mulching on water retention and temperature changes in loess soil

本研究量化了白膜和黑膜覆盖对黄棉土不同深度土壤水分和土壤温度的变化,探讨了地膜覆盖的"保水调温"效应。试验设置白膜、黑膜、未覆膜3个处理,监测覆盖处理下不同深度土壤温度,选用正弦曲线拟合和方程模型,量化分析黄绵土在不同覆盖条件下土壤水分、土壤温度和热容量变化过程。研究发现,40 cm深度处土壤水分和土壤热容量值均最大,10 cm深度处值最小。在0:00~8:00,黑膜覆盖下土壤温度普遍高于白膜覆盖,黑膜覆盖夜间保温性更好;8:00~16:00,白膜覆盖下土壤温度增加速率更快,对地温提升优于黑膜覆盖,白膜覆盖下土壤温度"峰值"出现比黑膜早1 h左右。覆盖处理均表现为浅层土壤(0~20 cm)升温快,降温也快,土壤温差变化幅度大于深层土壤(20~40 cm);随着土壤深度的增加,覆盖地膜对土壤增温效应不明显,土壤热容量显著增加。覆盖白膜、黑膜均能显著提高土壤水分和土壤温度,增加土壤热容量。白膜覆盖对土壤增温效应要大于黑膜覆盖的增温效应;白膜覆盖条件下土壤温度温差最大,未覆膜处理次之,黑膜覆盖处理最小。

In order to understand the effects of film mulching on water retention and temperature changes in different soil depths of loess soil,the sinusoidal model and fitting equation were used to analyze the soil temperature changes quantitatively under colorless film mulching,black film mulching and no film mulching.The results showed that soil moisture and soil heat capacity were with the largest values at the depth of 40 cm,while the lowest values were at 10 cm at 0:00~8:00 a.m.,respectively.The soil temperature under the black film mulching was generally higher than that of the colorless film mulching,with better heat holding capacity during night time.At 8:00 a.m.~16:00 p.m.,the soil temperature under the colorless film mulching increased quickly and the soil temperature peak appeared about 1h earlier than that of the black film mulching.The shallow soil(0~20 cm)temperature increased quickly but decreased quickly as well and its temperature amplitude change was larger than that of the deep soil(20~40 cm).The effect of film mulching on soil temperature was not significant with the increase in soil depth.The colorless film mulching and black film mulching significantly increased soil water content,soil temperature and soil heat capacity.The colorless film mulching is with a better heating effect than that of black film mulching;and the soil temperature amplitude changes in an order of colorless film mulching>no film mulching>black film mulching.