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通过对新疆典型灌区5块(1998地块、2002地块、2004地块、2006地块和2008地块)不同膜下滴灌应用年限农田进行连续4年的定点监测,每块地每月分别在膜内毛管处、棉花窄行中点、膜外两膜中点3个位置取样测试从地表向下0-60cm深处土样的盐分及离子含量,揭示长期膜下滴灌农田根区土壤盐分演变趋势。结果表明,在现行灌溉制度条件下,根区土壤盐分平均值、最大值、盐分方差和标准差均随膜下滴灌应用年限延长呈降低趋势,根区盐分平均值与膜下滴灌应用年限符合Allometric1指数函数模型,滴灌应用1~3年,相对荒地脱盐率可达85%左右,滴灌应用3~10年盐分降低趋势明显,滴灌10~15年相对荒地脱盐率稳定在95%左右。根区土壤盐分中Na+与Cl-2种离子含量随膜下滴灌年限延长而降低趋势明显,滴灌5年以后降低缓慢,年均含量低于0.15g/kg,脱盐率稳定在80%~90%之间,滴灌8~15年相对稳定;根区盐分离子组分中主要是Na+与Cl-,随滴灌应用年限延长而降低,其次是Ca2+、SO2-4、Mg2+3种离子,其他离子含量随滴灌应用年限延长无明显变化特征。根区盐分及离子降低的主要原因在于当地的灌溉制度,坚持现行的灌水制度虽然有利于膜下滴灌长期可持续应用,但应适当减少花铃后期及吐絮期的灌水定额以节约水资源。
Through continuous four-year fixed-point monitoring of five years of irrigated farmland under different drip irrigation conditions in five typical irrigated areas in Xinjiang (1998 plots, 2002 plots, 2004 plots, 2006 plots and 2008 plots) The capillary in the membrane, the midpoint of cotton narrow row, and the midpoint of the two films outside the membrane were sampled to test the salt and ion contents of the soil samples down to 0-60cm from the surface to reveal the evolution of soil salinity in the rootzone of long-term drip irrigation trend. The results showed that under the current irrigation regimes, the average, maximum, salinity variance and standard deviation of soil salt in the rootzone all decreased with the extension of the drip irrigation duration. The average salt content in the root zone and the drip irrigation duration were in accordance with Allometric1 According to the exponential function model, the application of drip irrigation for 1 to 3 years showed that the desalination rate of relative wasteland could reach 85%, and the application of drip irrigation showed obvious trend of decreasing salinity in 3 ~ 10 years. The content of Na + and Cl-2 ions in root zone soil salt decreased with the prolongation of drip irrigation time. After 5 years of drip irrigation, the content of Na + and Cl-2 ions decreased slowly, the annual average content was less than 0.15g / kg and the desalination rate was stable at 80% -90% , Drip irrigation is relatively stable from 8 to 15 years; the salt components in the root zone are mainly Na + and Cl-, which decreases with the prolongation of drip irrigation application period, followed by Ca2 +, SO2-4 and Mg2 + ions, and other ion contents With the application of drip irrigation years without significant changes in characteristics. The main reason for the decrease of salt and ion in the root zone lies in the local irrigation system. While insisting that the current irrigation system is conducive to the long-term sustainable application of drip irrigation, it is necessary to reduce the irrigation quotas at the late flowering stage and the boll opening stage to save water resources.