Agricultural managed aquifer recharge (Ag-MAR) is a concept in which farmland is flooded during the winter using excess surface water to recharge the underlying groundwater. In this study, we show how different recharge practices affect NO₃⁻ leaching and mineralization–denitrification processes in different soil systems. Two contrasting soil textures (sand and fine sandy loam) from the Central Valley, California, were repeatedly flooded with 15 cm of water at varying time intervals in field and soil column experiments. Nitrogen species (NO₃^–, NH₄⁺, total N), total C, dissolved O₂, and moisture content were measured throughout the experiments. Results show that when flooding occurs at longer intervals (every 1–2 wk), N mineralization increases, leading to an increase of mobile NO₃⁻ in the upper root zone and leaching of significant quantities of NO₃⁻ from both soil textures (137.3 ± 6.6% [sand] and 145.7 ± 5.8% [fine sandy loam] of initial residual soil NO₃⁻) during subsequent flooding events. Laboratory mineralization incubations show that long flooding intervals promote mineralization and production of excess NO₃⁻ at rates of 0.11–3.93 mg N kg^–1 wk^–1 (sand) and 0.08–3.41 mg N kg^–1 wk^–1 (fine sandy loam). Decreasing the flooding frequency to 72 h reduces potential mineralization, decreasing the amount of NO₃⁻ leached during flooding events (31.7 ± 3.8% [sand] and 64.7 ± 10.4% [fine sandy loam] of initial residual soil NO₃^–). The results indicate that implementing recharge as repeated events over a long (multiple-week) time horizon might increase the total amount of NO₃⁻ potentially available for leaching to groundwater.

中文翻译：

---

农业管理含水层补给对硝酸盐运输的影响：土壤质地和洪水频率的作用

农业管理的含水层补给 (Ag-MAR) 是一个概念，其中农田在冬季被淹没，使用过量的地表水来补给底层地下水。在本研究中，我们展示了不同的补给方式如何影响不同土壤系统中的NO ₃ ^-浸出和矿化-反硝化过程。在田间和土柱实验中，来自加利福尼亚州中央山谷的两种对比鲜明的土壤质地（沙土和细砂壤土）在不同的时间间隔内反复被 15 厘米的水淹没。氮种类（NO ₃ ^–，NH ₄ ⁺，总N），总C，溶解O ₂，并在整个实验过程中测量水分含量。结果表明，当发生洪水在更长的时间间隔（每隔1-2周），N矿化的增加，从而增加移动的NO ₃ ^-在上部根区域和显著量NO的浸出₃ ^-来自土壤纹理（137.3在随后的洪水事件中，初始残留土壤 NO ₃ ^- ) 的± 6.6% [砂] 和 145.7 ± 5.8% [细砂壤土] 。实验室矿化孵化表明，较长的洪水间隔以 0.11–3.93 mg N kg ^–1 wk ^–1（沙）和 0.08–3.41 mg N kg ^{–1 的}速率促进矿化和过量 NO ₃ ⁻的产生wk ^–1（细砂壤土）。将洪水频率降低至 72 小时可减少潜在矿化，减少洪水事件期间浸出的 NO ₃ ^-量（初始残留土壤 NO ₃ ^{– 的}31.7 ± 3.8% [砂] 和 64.7 ± 10.4% [细砂壤土] ）。结果表明，在较长（多周）时间范围内将补给作为重复事件实施可能会增加 NO ₃ ^-可能可用于浸出到地下水中的总量。