暗管排水对河套灌区下游盐碱地脱盐效果的影响

Influence of subsurface drainage on desalting effect of saline-alkali land in Hetao irrigated area

为改善河套灌区土壤盐渍化现状,提高作物产量,在河套灌区下游盐碱地开展暗管排水试验,设置埋深1.2 m、间距30 m(T1)和埋深0.8 m、间距20 m(T2)两种暗管排水埋深间距组合,通过分析土壤盐分和向日葵产量变化,对比不同暗管处理对该区土壤盐分的调控效果。结果表明:1)暗管埋设后,表层(0-20 cm)土壤含盐量变化最为剧烈,中层(20-60 cm)次之,深层(60-100 cm)较为稳定,全观测期内暗管排水控制区表层土壤已由中重度盐碱化(含盐量为5-8 g·kg^(-1))降至轻中度水平(2-6 g·kg^(-1));2)与暗管水平距离越近,土壤脱盐效果越好,T1和T2在0-100 cm土层的土壤脱盐率最大值分别为32.04%和42.44%;3)由土壤淋洗曲线拟合方程可知,在相同灌水量和土壤深度下,T2土壤淋洗脱盐效果优于T1,且水平距离暗管越远,土壤盐分淋洗效果越差;4)T1和T2的向日葵产量均显著高于空白对照处理(T0)(P<0.05),分别较T0增产34.29%和53.51%。研究结果为利用暗管排水技术改良河套灌区盐碱地提供一定理论依据。

To improve the current status of soil salinization in the Hetao irrigation area and increase crop yields,subsurface drainage experiments were carried out in saline-alkali soils in the lower reaches of the Hetao irrigation area.Three treatments on the depth and interval combination of subsurface drainage pipe were set up,including the burieddepth of 1.2 m with the interval of 30 m(T1),and the buried depth of 0.8 m with the interval of 20 m(T2).Changes in soil salinity and sunflower yield were analyzed to compare the effects of different subsurface drainage treatments on soil salinity in the area.The results show that:1)After the underground drainage pipe was buried,the salt content of the surface soil(0-20 cm)changed most drastically,followed by the middle layer(20-60 cm),and the deep layer(60-100 cm)was more stable.During the whole observation period,the soil salt content of the surface soil in the subsurface drainage control area was reduced from moderate to severe salinization level(5-8 g·kg^(-1))to mild to moderate level(2-6 g·kg^(-1)).2)The closer to the horizontal distance of underground pipe,the better the soil desalination effect.The maximum desalination rates of T1 and T2 in 0-100 cm soil layer were 32.04%and 42.44%,respectively.3)The fitting equation of the soil leaching curve showed that under the same irrigation volume and soil depth,the soil leaching salt effect of T2 was better than that of T1,and the further the horizontal distance from the underground tube,the worse the soil salt leaching effect.4)The sunflower yield of T1 and T2 were significantly higher than that of no buried pipe control(T0)(P<0.05),and the yield was increased by 34.29%and 53.51%,respectively,compared with T0.The research results can provide a theoretical basis for improving the saline-alkali land in Hetao irrigation area by using subsurface pipe drainage technology.