肥液浓度对土壤水力特性参数的影响

Effect of Fertilizer Concentration on Soil Hydraulic Parameters

为了研究不同肥液(尿素)浓度对土壤水力特性参数的影响,选取陕西省杨凌区一级阶地的砂壤土和三级阶地黏壤土为供试土壤进行一维垂直入渗试验,采用数值反演方法估算了不同肥液浓度条件下的土壤水力特性参数,并量化分析了土壤水力特性参数变化对累积入渗量的影响,最终建立了考虑肥液浓度变化的土壤水力特性参数估算式。结果表明,土壤饱和含水率θs、形状系数n、饱和导水率Ks均随肥液浓度的增大而逐渐增大,而进气值吸力的倒数α随肥液浓度的增大呈减小趋势;土壤水力特性参数对累积入渗量的敏感性关系为n>θs>Ks>α,其中α对累积入渗量的影响<10%;本试验条件下,θs、n与Ks与肥液浓度呈指数函数关系,利用估算结果模拟了一维垂直入渗过程中的累积入渗量和剖面含水率,并与实测值进行了比较,两者具有良好的一致性,说明所建考虑肥液浓度变化的土壤水力特性参数估算式是可靠的,研究结果可为农田水肥管理提供理论依据。

In order to study the effect of different fertilizer concentration(Urea)on soil hydraulic parameters,the sandy loam of three-stage terrace and clay loam of the first terrace in Yangling District of Shaanxi Province are used as the test soil,the parameters of soil hydraulic under different fertilizer concentration were estimated by numerical inversion method,and analyzes the influence of the change of soil hydraulic parameters on the cumulative infiltration quantitatively,Finally,the estimation formula of soil hydraulic parameters considering the change of fertilizer concentration was established.The results showed that with the increasing of fertilizer concentration,the saturated water content(θs),shape coefficient(n)and saturated hydraulic conductivity(Ks)of soil is increasing,but the suction of intake reciprocal value(α)decreased with the increasing of fertilizer concentration.The sensitivity of soil hydraulic parameters to cumulative infiltration is n>θs>Ks>α,and the influence ofαon cumulative infiltration is less than 10%.In this paper,the relationship betweenθs and Ksand the concentration of fertilizer solution is exponential function.Utilizing estimation result simulated the cumulative infiltration amount and water content of soil profile in the process of one-dimensional vertical infiltration,and compared with the measured value,the two are showing no difference,It shows that the formula of soil hydraulic characteristic parameters considering the change of fertilizer concentration is reliable,this study can provide theoretical basis for water and fertilizer management of farmland.