冻融期膜下滴灌棉田土壤温度盐分迁移特征

采用大田试验与室内分析相结合的方式研究了冻融期气温、土壤温度及盐分间的相互作用关系。结果表明:外界气温对冻融期土壤温度的影响随深度的增加而减弱;土壤消融前,地温随深度呈现递增趋势,土壤消融后,地温呈现随深度增大而减小的趋势;冻融期相邻两土层间地温在0.01的置信水平下保持极显著相关性,其决定系数均在0.8以上,且随深度的增加,各土层地温的相关性减弱;试验区土壤冻融期长达120 d左右,最大冻土深度约为80 cm,至3月上旬土壤完全解冻;整个冻融期可分为冻结带发育阶段、稳定冻结阶段及消融三个阶段,且此三阶段地温与土层深度间关系均可用公式精确拟合;冻融期土壤剖面盐分呈现随深度增加先增大后减小的趋势;处于冻结带中的土壤盐分保持0.3%以内的较低水平,属于非盐化土;80~120 cm深度存在稳定积盐层,且其盐分值基本表现出中度及重度盐化土的特征。

Study on movement characteristics of soil temperature and salt during freeze-thaw period

The interaction between soil temperature and soil salt movement during the freeze-thaw period was studied in an indoor laboratory and the field .The results indicated that the effect of air temperature on soil temperature was de-creased with the depth increased .Before the thawing period ,soil temperature appeared an increasing trend with soil depth ,but exhibited an opposite tread after thawing period .Correlation of soil temperatures between adjacent layers was significant at the 0 .01 level (2-tailed) ,and the decision coefficient was larger than 0 .8 .The correlation of soil tempera-ture became decreased with the depth .The duration of the freeze-thaw period reached a length of 120 days ,and the largest depth of frozen soil was about 80cm .The frozen soil was completely thawed at the first ten-day of March .The whole freeze-thaw period could be divided into three stages:the first stage was frozen zone development ,the second one was stable frozen stage and the third was the thawing period ,which fitted accurately with the function .The soil salt con-tent presented an increasing trend firstly ,and then became decreased with depth .The value of soil salt content in frozen zone was about 0 .3% ,which belonged to the non-salinization soil .There was a stable salt accumulation layer at the depth of 80~120 cm ,which presented the characteristic of moderately and severely salinized soil .