典型经验根系吸水函数的田间模拟检验及评价

Field Test and Evaluation of Empirical Root Uptake Functions in Soil Water Movement Models

根据田间实测的作物生理数据和土壤水动态观测资料，确定了冬小麦拔节－开花生长阶段两个根系吸水函数（Ｆｅｄｄｅｓ，ｖａｎＧｅｎｕｃｈｔｅｎ）的特定解析式。在实验小区实测的气象数据和室内外试验得到的土壤水力特性参数基础上，对吸水函数进行田间模拟检验，并依据灵敏度分析结果比较两者间的差异、评价各自的特点。尽管两个根系吸水函数得到的模拟结果与土壤含水量实测值间的差异均较小，但Ｆｅｄｄｅｓ函数要比后者在土壤水分条件改变和根系吸水强度差异对作物根系吸水量的影响上反应更灵敏，故模拟结果应更趋合理、切合实际。

Two typically empirical root water uptake functions proposed by Feddes et al and van Genuchten were tested and evaluated through a numerical simulation to actual water management practice under a full irrigation regime. Simulations, moreover, were performed to test the sensitivity of the two functions to soil moisture situation and distribution of root mass density, and to compare the details of their respective form and function. It is concluded from results above that the Feddes water uptake function tested in this study is shown to have a broad range of sensitivity to fluctuations and changes in both the matric pressure of the soil and the distribution of root mass density along the profile of root zone. Even though the two functions were empirically derived, the Feddes function tends to provide reasonable calculations of the crop transpiration rate and to imitate the natural system better than the van Genuchten function.