地下水浅埋区重度盐碱地不同滴灌种植年限土壤盐分分布特征

采用时空替代的研究方法,研究地下水浅埋区重度盐碱地不同滴灌种植年限(0、1、2、3年)对土壤盐分及不同盐分离子分布的影响,旨在为采用覆膜滴灌技术进行盐碱地改良提供理论依据。试验结果表明滴灌种植枸杞第1年,土壤盐分变化主要为自上而下被淋洗,种植2年和3年土壤年内盐分含量和分布变化相似,盐分主要分布在土壤表层,且在枸杞生育期结束时,剖面土壤含盐量都低于年初水平;土壤溶液电导率(EC1:5)与主要离子之间都具有极显著的相关关系,其中Cl-和Na+与EC1:5关系最为紧密;HCO3-与EC1:5负相关,相关性随着种植年限的增加而减小;Cl-、Mg2+、Ca2+、Na+在盐分组成中的荷载随种植年限增加而增大;回归分析表明Cl-和EC1:5之间具有线性关系,SO42-与EC1:5之间具有对数关系,EC1:5可以通过Cl-和SO42-表达;利用咸水覆膜滴灌并没有根本改变土壤类型,但在距滴头水平距离0～30cm范围内土壤含盐量从13.1g/kg降低到4～6g/kg,由盐土脱盐演化为重度盐化土。因此,采用覆膜滴灌技术明显降低了作物根区盐分含量,改善了作物根系生长的土壤环境条件。

Characteristics of soil salinity distribution in saline-sodic soil with shallow water table under mulch-drip irrigation in different planting years

To provide the theory basis for the reasonable exploitation and sustainable utilization of saline-sodic soil by mulch-drip irrigation, the effect of mulch-drip irrigation on soil salinity in saline-sodic soil with shallow water table was studied. The method of time-space transformation was used to find out the characteristics of soil salinity distribution in saline-sodic soil planted for 1a, 2a and 3a, at the same time, the uncropped saline waste land adjacent to the experimental site was taken as the control (CK). The results showed that salt was leached downwards at the first planting year; the content and distribution of soil salt were similar at the second and third year of which soil electrical conductivity (EC1:5) was less than the first year; the correlations between EC1:5 and the major ions were significant at the 0.01 level, Cl- and Na+ were the most significant one while HCO3- is the negative one and decreased as the planting year increased. Principal component analysis indicated that the load of Cl-, Mg2+, Ca2+, and Na+ increased with planting years. Regression analysis showed that Cl- and SO42- could be used as major variations to express soil electrical conductivity; an apparently linear correlation was observed between Cl- and EC1:5 while a logarithmic correlation between SO42- and EC1:5. Though the type of soil did not change markedly under mulch-drip irrigation with saline water, soil within 30 cm to the drip line evolved from saline soil to heavy salt affected soil. It can be concluded that mulch-drip irrigation changes the distribution of soil salts and improves the soil environment for root growth, so it can be used to ameliorate and sustainably utilize the saline-sodic soil with shallow water table.