The use of brackish groundwater (BGW) to supplement irrigation shortfalls has increased because of decreasing surface water availability in the arid areas of the southern United States. Reuse of reverse osmosis (RO) concentrate, a by-product resulting from desalination of BGW, can increase irrigation portfolio. This 2-yr greenhouse study aimed to quantify changes in physical and thermal soil properties, and evapotranspiration (ET) rate of pecan [Carya illinoinensis (Wangenh.) K. Koch] irrigated with BGW and RO concentrate. Another objective was to predict soil thermal conductivity (K) using soil electrical conductivity (EC) and soil volumetric water content (VWC) data of 2017–2018. Three irrigation water treatments with four replications were prepared namely, control (EC = 0.8 dS m⁻¹), BGW (EC = 4.0 dS m⁻¹), and RO concentrate (EC = 8.0 dS m⁻¹). Soil physical properties determined were texture, moisture content, bulk density, hydraulic conductivity, and moisture retention. Thermal properties measured were conductivity (K), diffusivity (D), resistivity (ρ), and heat capacity (C). The ET and leaching fractions (LF) were determined using water balance. Pecan irrigated with RO concentrate had the lowest ET among irrigation treatments. Soil thermal conductivities and soil water contents in BGW and RO irrigated pots were higher than the control. However, increases in heat capacity with increasing irrigation water salinity were most pronounced. The new four parameters-based model using EC and VWC explained 96% of variability of K (average R² = .96, RMSE = 0.096, normalized RMSE [NRMSE] = 11.14%). The sensitivity analysis showed that the contribution of VWC to K was greater than that of EC. Results indicate that continuous irrigation with RO concentrate can be done for up to 1 yr. A new irrigation scheduling protocol based on optimal LF and soil salinity is needed to sustain pecan production in southern New Mexico.

中文翻译：

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微咸地下水和反渗透浓缩物影响土壤物理和热特性以及山核桃蒸发蒸腾

由于美国南部干旱地区的地表水供应减少，使用微咸水地下水 (BGW) 来补充灌溉短缺的情况有所增加。反渗透 (RO) 浓缩液（BGW 脱盐产生的副产品）的再利用可以增加灌溉组合。这项为期 2 年的温室研究旨在量化用 BGW 和 RO 浓缩液灌溉的山核桃 [ Carya illinoinensis (Wangenh.) K. Koch] 的物理和热土壤特性以及蒸发蒸腾 (ET) 率的变化。另一个目标是使用 2017-2018 年土壤电导率 (EC) 和土壤体积含水量 (VWC) 数据预测土壤热导率 ( K )。制备了四个重复的三个灌溉水处理，即对照（EC = 0.8 dS m^-1 )、BGW (EC = 4.0 dS m ^-1 ) 和 RO 浓缩物 (EC = 8.0 dS m ^-1 )。确定的土壤物理特性包括质地、水分含量、堆积密度、水力传导率和保水率。测量的热性能包括电导率 ( K )、扩散率 ( D )、电阻率 (ρ) 和热容量 ( C）。ET 和浸出分数 (LF) 使用水平衡确定。用 RO 浓缩液灌溉的山核桃在灌溉处理中具有最低的 ET。BGW和RO灌溉盆的土壤热导率和土壤含水量均高于对照。然而，随着灌溉水盐度的增加，热容量的增加最为明显。使用 EC 和 VWC 的基于四个参数的新模型解释了K 的96% 变异性（平均R ²  = .96，RMSE = 0.096，归一化 RMSE [NRMSE] = 11.14%）。敏感性分析表明，VWC 对K的贡献大于EC。结果表明，用 RO 浓缩液连续灌溉可以进行长达 1 年。需要基于最佳 LF 和土壤盐度的新灌溉调度协议来维持新墨西哥州南部的山核桃生产。