南疆棉花苗期覆膜地温变化分析

Analysis of temperature changes under film during cotton seedling stage in south Xinjiang

通过对新疆巴州灌溉试验站棉花苗期覆膜（膜下）与不覆膜（膜间）条件下土壤温度的监测,分析了两种条件下土壤温度的变化趋势。结果表明：5 cm土层在8∶00-16∶00地温处于升温阶段,膜下达到最高温度44℃,比相应膜间地温高8.5℃,随后逐渐降低;不同深度土壤达到最高温度出现的时间随土层深度的增加而滞后;表层5cm土层地温日变化过程可以利用正弦函数曲线进行较好的描述;膜下和膜间地温差值随时间的变化趋势是先增后减,峰值出现的时间随土层深度的增加而延迟,且变化幅度随土层深度的增加而趋于平缓;膜下5 cm土层深度的地温在8∶00-12∶00时间段增量最大,为13℃,而相应时间段膜间地温增量为8.5℃,说明覆膜对提高地温具有较好的效果。通过分析苗期内地温变化趋势,覆膜具有提高地温,减小地温变化幅度,避免因地温降幅过大而造成棉苗受灾。

The temperatures of film-mulched soil and that without mulching in cotton seedling stage in Xinjiang Bazhou Irrigation Experiment Station are compared.The temperature of the 5 cm soil layer under film increases from 8∶00 and decreases after achieving to the peak of 44℃ at 16∶00.The temperature vs.the time curve can be fitted well by the sine function and it shows that the occurrence of the peak temperature gets increasingly later with the increase of soil depth.The difference between the soil temperature under film and that between films increases first and then decreases,and the time of the peak occurrence is delayed by the depth of the soil,and the changing amplitude tends to be stable with the increase of soil depth.The temperature of the 5 cm soil layer increases by 13℃ under film from 8∶00～12∶00 while by 8.5℃ between films,indicating that film mulching has good effects on improving soil temperature.By analyzing soil temperature trend in seedling stage,it is found that film mulching can increase temperature and reduce the rate of temperature change thus to avoid the damage to cotton caused by excessive temperature drop.