保水剂底施对沙子剖面水分和硝态氮运移的影响研究

【目的】解决沙土地区漏水漏肥的核心问题,建立保水防渗漏新技术体系,促进沙土地区农业可持续发展。【方法】基于保水剂的吸水保肥等物理化学特点,以保水剂和土壤混合物底施为技术方法,选用聚丙烯酸钠和壤土为材料,采用沙柱模拟试验,研究了不同施用厚度的保水剂-土壤混合物对剖面水分运移及硝态氮淋洗的影响。【结果】聚丙烯酸钠在壤土中的质量分数为1%时,可以对水分有效截流;混合物底施,以0.9～1.5 cm厚度为最佳;淋溶试验表明硝态氮主要集中在表层和保水剂层,占比为87.2%,有效防止了硝态氮的下移。【结论】保水剂壤土混合物底施,可以起到显著的水分养分截流作用,本试验中聚丙烯酸钠质量分数1%及1 cm厚度时,可获得较好效果。

Movement of Water and Nitrate in Sandy Soil Containing a Layer of Mixture of Water-absorbing Polymer and Soil

【Objective】Water-adsorbing polymers have been used an agent to improve the ability of soil to retain water and the objective of this paper is to study the movement and retention of water and nitrate in soil containing a layer of mixture of water-adsorbing polymer and soil.【Method】Sodium polyacrylate(SAP) was used in this paper as the agent and based on its adsorptive ability to water and nitrate, the polymer was mixed with soil. A layer of such a mixture was packed at different depths in soil columns, and water and nitrate infiltration in the columns was studied experimentally to elucidate the impact of thickness and location of the mixture layer on water flow and nitrate leaching.【Result】The mixture became impermeable when the ratio of sodium polyacrylate to loam soil was higher than 1%. Packing a layer of the mixture 0.9～1.5 cm thick in subsoil worked well. The nitrate was mainly found in the top soil and in the mixture, accounting for 87.2% of the total nitrogen, effectively reducing nitrate leaching.【Conclusion】Applying a layer of the mixture of soil and sodium polyacrylate in subsoil can improve water retention and ameliorate nitrate leaching. In our experiment burying a 1 cm thick mixture with the sodium polyacrylate to loam soil ratio at 1% gave good results.