不同改良措施下新疆重度盐渍土壤盐分变化与脱盐效果

    Soil salinity dynamic change and desalting effect under different improvement measures in severe salinity soil in Xinjiang

    • 摘要: 为了比较盐渍化土壤不同改良措施的治理效果,以新疆新开垦的重度盐渍化农田为研究对象,设置5个处理分别为农业改良措施、根区隔盐+农业改良措施、暗管排盐+农业改良措施、化学改良+农业改良措施和天然对照区,通过3 a的试验研究土壤盐分运移的影响因素、动态变化与不同改良措施脱盐效果。结果表明:人为灌溉、农田蒸散量、地下水埋深与土壤盐分均达到极显著相关,生育期灌水对耕层土壤盐分影响最大,相关系数为?0.871。整个改良过程中农业改良措施处理表层和底层盐分含量较高,根区隔盐处理盐分表聚现象明显,暗管排盐、化学改良处理均表现出底层盐分明显高于表层。从各处理3a的脱盐效果来看,第1年脱盐效果均不理想,第2年脱盐率显著提升,其中根区隔盐和暗管排盐处理各土层脱盐率均超过44%,改良效果最好,由于土壤总盐分含量减少第3年各措施脱盐率明显降低。总体来看,各改良措施均能够有效降低耕层土壤盐分,根区隔盐、暗管排盐处理在0~80 cm耕层脱盐率分别为61.33%、59.37%,优于其他处理;化学改良处理0~40 cm土层脱盐效果优于底层,其脱盐率为55.32%,明显高于农业改良处理的脱盐率45.42%,但0~80 cm土层脱盐率2处理间差异不大。新疆盐碱化程度重,农田根区隔盐、暗管排盐工程改良结合农业深耕、秸秆还田、增施有机肥等措施是综合治理重度盐渍化土壤的有效途径,研究结果能够为新疆干旱区盐渍化土壤有效改良和合理开发利用提供理论依据和参考。

       

      Abstract: Abstract: Soil salinization can directly affect crop production, and threaten the sustainable utilization of irrigated land. This problem is particularly prominent in Xinjiang Uyghur Autonomous Region, where has much uncultivated arable land, and soil saline and secondary salinization after land development. In this study, field experiments were conducted to investigate the influence factors and characteristics of soil salt movement, as well as elution desalination in different improvement measures treatments of severe saline soil through 3-year experiment. Five improvement treatments were designed including agricultural improvement (mainly including mulched with plastic film, deep plowing, returning straw and organic fertilizer), salt-isolation to root zone plus agricultural improvement, subsurface pipe drainage plus agricultural improvement, chemical modified plus agricultural improvement, and control without any human activity on new reclamation farmland in Xinjiang Province. The results indicated that salt content of the soil was mainly affected by evaporation, irrigation amount and groundwater depth; the soil salt content was significantly negative correlated with irrigation amount (correlation coefficient=-0.871, P=0.0039) and groundwater depth (correlation coefficient=-0.831, P=0.0072), positively correlated with monthly evaporation (correlation coefficient=0.754, P=0.0084), but not significantly correlated with mean monthly temperatures; The effect of irrigation amount on the 0-80 cm soil salinity in entire growth period was the most prominent. In the 3-years, dynamic changes in soil saline content varied with different improvement methods: high salt content accumulated in the top and deep layers of soil throughout the growing period for agricultural improvement treatment; obvious salt accumulation in the top layer of soils for salt-isolation to root zone plus agricultural improvement; the salt content at the deep layer higher than in subsurface layer for pipe drainage plus agricultural improvement, and chemical modified plus agricultural improvement treatment. The desalination rate of soils after the first-year was not satisfactory, and that after the second-year was significantly improved. The desalination rate of soil in the treatment of salt-isolation to root zone plus agricultural improvement and subsurface pipe drainage plus agricultural improvement treatment was up to 44% in the second year, but was significantly decreased in the third-year due to the reduction of the total salt content of the soil. Overall, all the treatments could result in the decrease of soil salt content. Among them, the soil desalinization rates of agricultural improvement plus subsurface pipe drainage and salt-isolation to root zone plus agricultural improvement were 61.33% and 59.37% respectively in the 0 to 80 cm layers, which were better than the other treatment. The soil desalinization rate of chemical modified plus agricultural improvement treatment was 55.32% in the 0 to 40 cm layers, higher than agricultural improvement 45.42%. The results can provide valuble information for saline soil improvement and rational development and effective utilization of saline soils in the Xinjiang arid zone.

       

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