北疆常年膜下滴灌棉田土壤盐分年内及年际变化特征研究

Study on the variation characteristics of soil salt in cotton field during the year and interannual by perennial drip irrigation under plastic film in Northern Xinjiang

针对膜下滴灌棉田土壤次生盐渍化问题,从年内变化与年际变化两个方面,分析新疆典型绿洲区膜下滴灌棉田土壤盐分演变特征。研究结果表明：在年内,土壤盐分整体随生育期的顺延而呈下降趋势,其中5月上旬（苗期）、7月中旬（花铃期）、9月中旬（收获期）土壤盐分呈现积盐趋势;膜下滴灌4～12 a的棉田土壤存在稳定积盐层,其深度大约在60～150 cm范围内,其盐分值基本保持在0.6%上下;60 cm以上土层基本处于脱盐状态,其盐分值保持在0.2%～0.4%左右,属于非盐化土壤;膜下滴灌15 a的棉田,土壤盐分随生育阶段变化幅度较大,呈现中度盐化土特征。在年际间,膜下滴灌最初1～6 a,土壤盐分呈现持续脱盐趋势,尤其20 cm以下土层脱盐效果较为明显;实施膜下滴灌6～7 a,土壤盐分变化趋于稳定状态,各棉田出现稳定积盐层,其深度大约在80～100 cm土层,积盐层盐分值大部分保持在0.25%上下,属于非盐化土。

Aimed at the soil secondary salinization in cotton field by drip irrigation under plastic film, through two aspects as variation during the year and interannual, analyzed the soil salt evolving characteristics in typical oasis region in Xinjiang. The results indicated that： During the year, the soil salt content assumed a decreasing tendency along with growing season. Among them in early May （seedling stage）, middle July （blossom and boll-forming stages）, middle September（harvest time）, the soil salt presented an accumulated trend. There was a stable salt accumulated layer about 60 - 150 cm soil depth in cotton field by drip irrigation under plastic film for 4 - 12 years, the soil salt content in this layer was basically kept in 0.6% more or less. In 0 - 60cm soil layer was basically kept a desalination status, the soil salt content in this layer was kept in about 0.2% - 0.4%, which can be treated as non saline soil. For the cotton field by drip irrigation under plastic film lasting 15 years, the soil salt presented a large rangeability along with growing stage, and assumed a characteristic of moderate soil salinization. During the interannual, at the beginning 1 - 6 years by drip ir- rigation under plastic film, the soil salt assumed a continual decreasing trend, particularly for the layer of 0 - 20 cm soil depth, the desalination was rather obvious. Implemented drip irrigation under plastic film for 6 - 7 years, the change of soil salt trended a stable status, each cotton field appeared a stable salt accumulation layer, which was in 80- 100 cm soil depth and the salt value was kept about 0.25 %. which belonzs to non saline soil.