地下水浅埋区重度盐碱地覆膜咸水滴灌水盐动态试验研究

WATER AND SALT DYNAMICS OF SALINE-SODIC SOIL WITH SHALLOW WATER TABLE UNDER MULCH-DRIP IRRIGATION WITH SALINE WATER

通过在高垄埋设水银负压计,研究土壤水势动态,并在枸杞不同生育期对潜水位以上各土层盐分进行取样分析,研究土壤盐分周年动态变化,为地下水浅埋区重度盐碱地改良利用提供理论依据。结果表明,在覆膜滴灌一个灌溉周期内,土壤水分运动始终为自滴头下方饱和区持续径向向外扩散;雨季降雨使水分从土壤剖面整体向下运动,随着潜水位的升高水分运动逐渐减弱,转为自垄中部向垄坡方向运动。盐分运动受水分运动影响明显,周年盐分动态可以分为春季强烈蒸发—积盐阶段、灌溉淋洗—稳定阶段、雨季淋溶—脱盐阶段、秋季蒸发—积盐阶段和冬季相对稳定阶段五个阶段。剖面土壤电导率(EC1∶5)均值从1.64 dS m-1增长至1.69 dS m-1,土壤未明显积盐,但盐分在剖面分布的周年变化表明滴灌灌溉调控了水分盐分在土壤中的分布,为作物根系生长提供了良好的土壤环境条件。因此,地下水浅埋区重度盐碱地可以通过高垄覆膜咸水滴灌技术加以利用。

To study annual dynamic variation of soil salt and provide theoretical basis for reasonable exploitation and sustainable utilization of saline-sodic soil with shallow water table,soil water potential was observed by tensiometer and water samples were taken from various soil layers above the water table at different growth stages of Lycium barbarum L.Results show that water kept diffusing radially from the saturated zone right below the dripper within each mulch-drip-irrigation cycle,and moved downwards from the upper layer to the deeper layers during the rainy season;The downwards trend slowed down as the water table rose up,and the soil water began to move from the center towards the side slope of the ridge.Salt movement was obviously affected by water movement and it could be divided into five phases in a year： salt accumulation phase-strong evaporation in spring;stable phase-irrigation and salt-washing;desalting phase-leaching in rainy season;salt accumulation phase-evaporation in fall;and relatively stable phase in winter.In the experiment field,after mulch-drip irrigation for a year,salt accumulated insignificantly and the mean EC1∶ 5 of the profile rose from 1.64 dS m^-1 to 1.69 dS m^-1.The variation of the distribution of salt in the profile indicated that mulch-drip irrigation regulated the distribution of salt in the soil,creating a benign soil environment for crop roots to grow in.So saline-sodic soils with shallow water table can be exploited and utilized with the aid of the technique of mulch-drip irrigation with saline water.