高水位区暗管埋设下土壤盐分适时立体调控的生态效应

Ecological effects of soil salinity regulation through saline water irrigation and subsurface drainage in high water table level area

高水位地区作物生长关键期采用微咸水或咸水灌溉被证明在一定条件下可以起到增产正效应,但同时却存在着土体盐分积累及其对下茬或次年种植影响的生态负效应.为探讨消除或抑制微咸水或咸水灌溉对土壤盐分积累的生态负效应,保证作物种植增产的正效应,本文在河北近滨海高水位盐碱区开展了为期2年的试验研究,探讨了旱季微咸水或咸水灌溉带来的盐分异位积累与离子分布变化特征,分析了雨季关键期暗管适时排盐对土壤盐分的立体调控生态效应.结果表明:旱季咸水灌溉后土壤经历"积盐-脱盐-二次积盐"3个阶段;灌溉初期,1 g·L^(-1)咸水灌溉处理下0~50 cm土体脱盐,土壤含盐量随土壤深度增加而增加,HCO_3^-含量增加,其他离子含量降低;6与13 g·L^(-1)咸水灌溉处理下0~50 cm土体积盐,土壤含盐量随土壤深度增加而降低,HCO_3^-含量降低,其他离子含量增加;雨季暗管适时立体调控脱盐效果显著,土壤脱盐率达16.0%~45.7%,同降雨量下,降水分布越集中,脱盐效果越好;周年时间尺度上,咸水灌溉小区土壤积盐量小于对照区;咸水灌溉处理小区冬小麦产量显著高于对照处理,1 g·L^(-1)处理高于6与13 g·L^(-1)处理.

In high water table level area,saline water irrigation in crucial drought periods has been confirmed to have a positive effect to increase crop yield while it may cause soil salt accumulation to have a potential negative effect on next season crop growth.It was supposed that eliminating or reducing this kind of negative effect could ensure a sustainable increase of crop yield under saline water irrigation.Field experiments were completed in a 2-year period in Nandagang district in coastal area of Hebei Province.We investigated the dynamic changes of soil salt accumulation under saline water irrigation in dry season,and analyzed the ecological effect of removing soil salt storage by subsurface pipe drainage system in rainy or proper season.The results showed that the soil salinity experienced accumulation-desalinization-secondary accumulation under saline water irrigation in dry season.In the early stage of irrigation,under 1 g·L^（-1）concentration saline water irrigation treatment,the soil salt load was obviously removed in the layer of 0-50 cm,the soil salinity went up with soil depth,HCO_3^-content increased whereas other ions contents decreased; under 6 g ·L^（-1）and 13 g·L^（-1）concentration saline water irrigation treatments,the soil salt accumulated in the layer of 0-50 cm,the soil salinity went down with soil depth,HCO_3^-content decreased whereas other ions contents increased.Leaching effect of soil salt under subsurface pipe drainage system during rainy or proper season was significant.The soil desalinization ratio increased with the rainfall strength,ranging from 16.0% to 45.7%.On a yearly scale,the soil salt accumulation under saline water irrigation was lower than that in control area.The wheat yield under saline water irrigation was significantly higher than that in control area,and the yield in the treatment of 1 g·L^（-1）was highest.