Agricultural Managed Aquifer Recharge (Ag-MAR) is an emerging MAR technique that uses agricultural fields as percolation basins to recharge the underlying aquifers. Ag-MAR can be a beneficial solution for storing excess surface water, however, if not managed properly it can potentially harm the soil and crops planted on the field at the time of recharge, ultimately leading to yield loss. Root zone residence time (RZRT), defined as the duration that the root-zone can remain saturated (or nearly saturated) during Ag-MAR without crop damage, is a key factor in Ag-MAR since extended periods of saturation in the root-zone can damage crops. Here we propose a simple RZRT model for estimating a safe Ag-MAR flooding duration based on hydraulic parameters deduced from soil texture, crop tolerance to saturation, effective root depth, and critical soil water content, which is the point where soil re-aeration occurs during drainage. We tested the model with different hydraulic parameter sets and compared the results to observed data and HYDRUS simulations. Using fitted and unfitted hydraulic parameters the average error of the predicted Ag-MAR flooding duration was less than 5 h, and up to a few days, respectively. Consequently, for crops with low flooding-tolerance, the model should be used with caution, but for more tolerant crops, the model provides reasonable predictions. The model also provides a first approximation of the possible amount of water that can be applied during an Ag-MAR event. Based on the RZRT model, we evaluated the Ag-MAR potential of various crops and effective root depths for each of the USDA soil texture classes. A spreadsheet containing the RZRT model including hydraulic parameters, and crop properties is publicly available and can be used as a learning tool or to estimate Ag-MAR flooding duration for different soils. The proposed model can be easily integrated into Ag-MAR assessment tools.

农业管理含水层补给 (Ag-MAR) 是一种新兴的 MAR 技术，它使用农田作为渗滤池来补给底层含水层。Ag-MAR 可以是储存过量地表水的有益解决方案，但是，如果管理不当，它可能会在补给时损害土壤和田间种植的作物，最终导致产量损失。根区停留时间 (RZRT)，定义为在 Ag-MAR 期间根区可以保持饱和（或接近饱和）而不会损坏作物的持续时间，是 Ag-MAR 的关键因素，因为根部饱和时间延长区域会损坏农作物。在这里，我们提出了一个简单的 RZRT 模型，用于根据从土壤质地、作物对饱和度的耐受性、有效根深、临界土壤含水量，这是在排水过程中发生土壤再曝气的点。我们使用不同的水力参数集测试了模型，并将结果与​​观察到的数据和 HYDRUS 模拟进行了比较。使用拟合和未拟合的水力参数，预测的 Ag-MAR 洪水持续时间的平均误差分别小于 5 小时和最多几天。因此，对于耐涝性较低的作物，应谨慎使用该模型，但对于耐涝性较高的作物，该模型提供了合理的预测。该模型还提供了在 Ag-MAR 事件期间可以应用的可能水量的初步近似值。基于 RZRT 模型，我们评估了各种作物的 Ag-MAR 潜力和每个美国农业部土壤质地类别的有效根深。包含 RZRT 模型（包括水力参数和作物特性）的电子表格是公开可用的，可用作学习工具或估计不同土壤的 Ag-MAR 洪水持续时间。所提出的模型可以很容易地集成到 Ag-MAR 评估工具中。