摘要
保水剂在农业上的应用对于缓解干旱具有重要的意义,但其应用后会发生降解而最终失去保水作用,因此了解其在降解过程中引起的土壤物理性质的动态变化及水分运动的机理,是其能否正确应用的关键,本试验以保水剂在农业应用中的典型用量为基础,研究了保水剂对土壤的物理性质动态影响及一维土壤水分。结果表明,保水剂施入土壤后其性能不断衰减是导致土壤物理性质不断变化的最根本原因;土壤中施用保水剂后土壤的质量饱和含水率明显增加,饱和导水率降低,但随着保水剂性能的逐渐衰减,饱和含水率呈现下降趋势,饱和导水率呈现上升趋势;施入保水剂后土壤的扩散率是一个曲面,并且随着保水剂自身性能的衰减,呈现逐渐扩展的趋势;施用保水剂后土壤入渗的湿润锋前进速度下降,这主要是由于施用保水剂土壤的饱和含水量增加和保水剂膨胀堵塞土壤孔隙造成的;通过对施用保水剂土壤的扩散率和导水率的分时段研究,最终建立施用保水剂土壤的一维水分运动方程5 H5t=55z D(H,T)5 H5z-5K(H,T)5z,试验证明其可行,且精度在允许的范围内。
Super Absorbent Polymer （SAP） is of important significance in mitigating agricultural drought .However , its role in water retention ultimately fades away due to its degradation after application .Therefore ,the investigation of the dynamic change of soil physical properties and the mechanism of moisture movement caused by degradation of SAP is the key for its proper application .Based on the typical amount of SAP used in agriculture ,the dynamic impacts of SAP on soil physical properties and one-dimensional soil moisture were analyzed .The results showed that the attenuation of SAP performance after its application into soil was the most fundamental reason for the constant change of soil physical proper-ties .After treated with SAP ,the saturated mass water content of soil was significantly increased ,and the saturated hy-draulic conductivity was reduced .However ,as the SAP performance attenuated ,the saturated moisture content showed a downward trend and the saturated hydraulic conductivity showed an upward trend .After treated with SAP ,the water dif-fusivity of soil exhibited a curved surface and showed a gradually expanding trend with the attenuation of its performance . The forward speed of moist sharp point of infiltration in SAP-treated soil was reduced ,which was mainly because that the saturated moisture content of soil was increased and the soil pores were clogged due to the expansion of SAP after it was applied .By investigating the water diffusivity and hydraulic conductivity of SAP-treated soil at different time periods ,a one-dimensional water movement equation was finally established as эθ/эt=э/эz D （θ,T ）эθ/эz -эK （θ,T ）/эz .It was proved to be feasible with the accuracy within an allowable range .
出处
《干旱地区农业研究》
CSCD
北大核心
2013年第5期161-167,共7页
Agricultural Research in the Arid Areas
基金
北京林业大学青年科技启动基金(BLX2011009)
国家自然科学基金重点资助项目(51239009)
关键词
保水剂
饱和含水率
饱和导水率
扩散率
入渗模拟
Super Absorbent Polymer
saturated water content
saturated hydraulic conductivity
soil water diffusivity
infiltration simulation
