Saturated, , and near-saturated, , soil hydraulic conductivity control many hydrological processes but they are difficult to measure. Comparing methods to determine and is a means to establish how and why these soil hydrodynamic properties vary with the applied method. A comparison was established between the and values of a sandy-loam soil obtained, in the field, with the BEST (Beerkan Estimation of Soil Transfer parameters) method of soil hydraulic characterization and an unconfined MDI (mini-disk infiltrometer) experiment and, in the laboratory, with a confined MDI experiment and the CHP (constant-head permeameter) method. Using for the BEST calculations the soil porosity instead of the saturated soil water content yielded 1.4–1.1 times higher estimates of and , depending on the pressure head, and differences decreased in more unsaturated soil conditions. The confined MDI experiment yielded 22 % - 77 % higher values than the unconfined MDI experiment, depending on the established pressure head, , and differences were not significant for = −1 cm. In the close to saturation region, the soil hydraulic conductivity function predicted with BEST did not generally agree well with the and values obtained in the laboratory by a direct application of the Darcy’s law. In particular, BEST yielded a 5.6 times smaller value than the CHP method and up to an 8.1 times higher value than the MDI. Overall, i) the two application methods of the MDI yielded relatively similar results, especially close to saturation, and ii) there was not a satisfactory agreement between the field (BEST) and the laboratory (MDI plus CHP) determination of soil hydraulic conductivity close to saturation, unless a comparison was made with the same soil water content. The detected differences were probably attributable to soil spatial variability, overestimation of in the laboratory due to preferential flow phenomena, underestimation of in the field due to air entrapment in the soil and infiltration surface disturbance, inability of BEST to describe the actual soil hydraulic conductivity function at the sampled field site. Testing BEST predictions of and in other soils appears advisable and combining the MDI and CHP methods appears a rather simple means to make these checks. These additional investigations could improve interpretation of the differences between methods, which is an important step for properly selecting a method yielding and data appropriate for an intended use.

中文翻译：

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比较微型圆盘渗透仪、BEST 方法和砂壤土导水率土芯估计值


饱和和近饱和土壤导水率控制着许多水文过程，但它们难以测量。比较确定和确定这些土壤水动力特性如何以及为何随所应用的方法而变化的方法是一种手段。通过土壤水力表征的 BEST（土壤迁移参数的比尔坎估计）方法和无侧限 MDI（微型圆盘渗透计）实验，对现场获得的沙壤土的 和 值进行了比较，并在实验室，采用密闭 MDI 实验和 CHP（常压头渗透计）方法。在最佳计算中，使用土壤孔隙率代替饱和土壤含水量，得到的 和 估计值高出 1.4-1.1 倍，具体取决于压力水头，并且在更不饱和的土壤条件下差异会减小。受限 MDI 实验产生的值比无受限 MDI 实验高 22% - 77%，具体取决于建立的压头 ，且对于 = −1 cm 时差异不显着。在接近饱和区，BEST 预测的土壤导水率函数与实验室直接应用达西定律获得的 和 值总体上不太吻合。特别是，BEST 产生的值比 CHP 方法小 5.6 倍，比 MDI 方法高 8.1 倍。总体而言，i) MDI 的两种应用方法产生了相对相似的结果，特别是接近饱和，并且 ii) 土壤导水率的现场（BEST）和实验室（MDI 加 CHP）测定之间没有令人满意的一致性饱和度，除非与相同的土壤含水量进行比较。 检测到的差异可能归因于土壤空间变异性、由于优先流现象而在实验室中高估了 、由于土壤中的空气截留和渗透表面扰动而在现场低估了 、BEST 无法描述实际的土壤导水率函数在采样现场。在其他土壤中测试 BEST 预测似乎是可取的，并且结合 MDI 和 CHP 方法似乎是进行这些检查的相当简单的方法。这些额外的研究可以改善对方法之间差异的解释，这是正确选择适合预期用途的方法和数据的重要步骤。