暗管排盐条件下园林废弃物与膨润土对滨海盐土的改良效果研究

Study on the Amelioration Effect of Garden Waste and Bentonite on Coastal Saline Soil Under Subsurface Drainage

为了有效利用资源,提高滨海盐土的改良效果,通过土柱和大田试验,研究暗管排盐淋洗作用下膨润土和发酵园林废弃物单独施用与混合施用对土壤容重、总孔隙度、饱和导水率、pH值、养分含量、Na+和Ca2+离子交换过程及土壤脱盐率的影响.研究结果表明:在土柱淋洗试验中膨润土和发酵园林废弃物都具有降低土壤pH值、含盐量和钠吸附比的作用,膨润土对土壤胶体中的Na+具有离子交换作用,可以促进Na+的淋溶量的增加,提高土壤的脱盐效果.发酵园林废弃物的施用增大了土粒间孔隙,初始入渗率得到提高.选用3%(质量比)的膨润土和发酵园林废弃物比较大田试验中的应用效果表明,淋洗结束初期膨润土、发酵园林废弃物以及混施对土壤脱盐作用与土柱试验一致,但一年后单施膨润土和园林废弃物土壤含盐量明显增加,0~20cm土层含盐量分别为淋洗初期的19.97倍和6.66倍.综合土壤脱盐效果与土壤理化性质,3%膨润土与发酵园林废弃物混施在大田应用中改良效果最好,既降低了土壤含盐量,脱盐率达到81.79%~52.28%,又显著了提高土壤养分含量与渗透性,对改善滨海地区盐渍土土壤结构与理化性质具有重要意义.

To effectively utilize resources and improve the amelioration effects on coastal saline soil,the soil bulk density,total porosity,saturated hydraulic conductivity,nutrient content,Na+and Ca2+ion exchange processes,and soil desalination rate of bentonite and garden waste compost under the action of subsurface drainage salt leaching were analyzed through soil column and field experiments.The results of the soil column leaching experiment indicate that both bentonite and garden waste compost reduce the soil pH,salt content,and sodium adsorption ratio.Bentonite has an ion exchange effect on Na+in soil colloids,which can promote an increase in the Na+leaching volume and improve the desalting effect of soil.Improvements in the soil particle porosity and the initial infiltration rate were observed with the application of garden compost.Utilizing a 3%mass ratio of bentonite and garden waste showed that the desalination of the bentonite,garden waste compost,and mixed application in the initial stage of the leaching was consistent with the soil column tests.Observations after a one-year period showed a significant increase in the soil salinity of the bentonite and garden waste compost.The salt content of the soil layer at 0~20 cm was 19.97 times to 6.66 times higher than that in the initial leaching stage.A mixture of 3%bentonite and garden compost improved the reduction in soil salinity while increasing the permeability and nutrient content.Therefore,a mixture of bentonite and garden compost can help improve the soil structure and its physical-chemical properties in coastal areas.