紫花苜蓿不同根系分布模式的土壤水分模拟和验证

Simulation and verification of soil moisture of root distribution functions for alfalfa

根系分布影响着土壤水分养分吸收,实测根系分布费时费力,经验根系分布函数参数简单,应用方便。该研究在田间采用苜蓿栽培土柱试验,测定根系分布,并将其和不同经验根系分布函数分别应用于Hydrus-1D对土壤水分进行动态模拟,通过土壤水分实测值和模拟值比较,验证分析了经验根系分布函数的适用性以及对土壤水分动态变化的影响。结果表明:拟合的根系分布、Prasad分布、Hoffman和van Genuchten分布3种根系分布函数的根长密度模拟值与36cm以下的根长密度实测值较为吻合,Raats根系分布模拟值与实测值及其他分布函数则差别较大。不同根系分布下土壤水分模拟差别不大,平均相对均方根误差在3.5%以下。非胁迫生长条件下,Prasad根系分布、Hoffman和vanGenuchten根系分布都可描述紫花苜蓿实际根系分布状况。

Root distribution has a significant impact on soil moisture and nutrient uptake. It is time and effort consuming to measure root distribution,but it is easy to study root distribution by empirical functions. Soil column experiments in field were conducted to measure alfalfa root distribution. Empirical root distribution functions were compared with measured data,and they were respectively incorporated in the Hydrus-1D software to simulate soil water movement. Consequently,the applicability of empirical root distribution functions and the effect of empirical root distribution functions on soil moisture dynamic change were verified and analyzed by comparing of measured and simulated values of soil moisture. The results showed that the simulated values of root density by functions of fitting root distribution,Prasad distribution and Hoffman and van Genuchten distribution were coincide well with measured values below 36 cm. The value of Raats root distribution was different with other distribution function values and the measured values. Different distribution functions resulted in nearly identical soil moisture,and the average relative root mean square error were below 3.5%. Raats root distribution,Prasad distribution and Hoffman and van Genuchten distribution all can describe the practical root distribution of alfalfa under non-stress growth condition