In many orchards, irrigation scheduling is designed based on data from meteorological networks and considering homogeneous soil properties. Such assumptions may result in inefficient irrigation, which is difficult to constrain without expensive or invasive techniques. Here we have evaluated the ability of the electrical resistivity tomography (ERT) for detecting meter-scale irrigation uniformity and deep percolation during irrigation. The spatiotemporal variability of soil volumetric water content (VWC) in a vineyard located near Santiago (Chile) was inferred using ERT monitoring of two irrigation cycles. The electrical resistivity structure up to 4 m depth was estimated using two-dimensional inversion of ERT data. ERT results were verified by comparing resistivity models with VWC measured with soil moisture sensors, soil properties mapped in a 2 m-depth soil pit, and the spatiotemporal evolution of VWC obtained by solving numerically Richards equation. Largest temporal variations of resistivity were observed within the root depth (1 m) and are consistent with expected relative changes in VWC during irrigation. ERT images exhibit lateral changes in resistivity at these depths, likely indicating non-uniform infiltration of water controlled by observed soil texture variations. Resistivity changes were also observed below the root zone, suggesting that a fraction of the irrigation water percolates downward. These findings can be explained by an excess of irrigation water applied during the monitoring, which was planned considering regional evapotranspiration (ET) data that overestimated the actual ET measured at the vineyard. Altogether, our results suggest that ERT monitoring during irrigation is a cost-effective tool to constrain the performance of irrigation systems.

中文翻译：

---

土壤电阻率监测作为评估果园规模灌溉系统效率的实用工具：智利中部葡萄园的案例研究

在许多果园中，灌溉计划是根据气象网络数据并考虑均质土壤特性而设计的。这种假设可能会导致灌溉效率低下，如果没有昂贵或侵入性的技术，就很难限制这种情况。在这里，我们评估了电阻率层析成像 (ERT) 在灌溉过程中检测米级灌溉均匀性和深层渗透的能力。使用 ERT 监测两个灌溉周期来推断位于圣地亚哥（智利）附近葡萄园的土壤体积含水量 (VWC) 的时空变异性。使用 ERT 数据的二维反演估计深度达 4 m 的电阻率结构。通过将电阻率模型与土壤湿度传感器测量的 VWC 进行比较，验证了 ERT 结果，绘制在 2 m 深土坑中的土壤特性，以及通过数值求解理查兹方程获得的 VWC 的时空演变。在根深 (1 m) 内观察到电阻率的最大时间变化，并且与灌溉期间 VWC 的预期相对变化一致。ERT 图像在这些深度显示电阻率的横向变化，可能表明由观察到的土壤质地变化控制的水的非均匀渗透。在根区下方也观察到电阻率变化，表明一部分灌溉水向下渗透。这些发现可以通过监测期间使用过量的灌溉水来解释，这是考虑到区域蒸散 (ET) 数据高估了在葡萄园测量的实际 ET 而计划的。共，