Mobilization of phosphorus (P) in arable soils might be affected by groundwater fluctuations and the associated changes in redox potential (E_H). However, the impact of systematic changes of E_H on P mobilization in redoximorphic arable soils along a catena has not been studied so far. Therefore, we investigated P mobilization under different redox conditions in top- and sub-soil horizons of three groundwater affected arable soils along a slight slope (toe-, mid-, and upper-slope position) in Northern Germany using an automated biogeochemical microcosm system. The impact of pH, Al, Fe, Mn, and dissolved organic carbon (DOC) on P mobilization was also studied. The initial E_H (+351 to +431 mV) and pH (6.5–7.0) decreased in all soil samples (E_H = −280 mV; pH = 4.4) when creating a slurry. Thereafter, the pH increased to 7.1 and 6.4 with increasing E_H in the mid-and toe-slope soil, respectively. Concentrations of dissolved P ranged between 20.8 mg L⁻¹ under low E_H in the toe slope topsoil and 0.69 mg L⁻¹ under high E_H in the toe- and mid-slop subsoil. Concentrations (mg L⁻¹) of dissolved Fe (0.31–13.3) and DOC (92–2651) increased under low E_H and decreased under high E_H. The increase of P mobilization under low E_H and pH in the soils might be due to the release of P via the reductive and acidic dissolution of Fe-(oxhydr)oxides and/or due to soil organic matter mineralization. The high mobilization of P under reducing conditions may increase its bioavailability; however, it may increase its loss in the soils, particularly in the toe slope profile.

耕作土壤中磷（P）的动员可能会受到地下水波动和氧化还原电位（E _H）相关变化的影响。但是，到目前为止，尚未研究过E _H的系统变化对沿连环连接的氧化还原型可耕土壤中P迁移的影响。因此，我们使用自动化的生物地球化学缩影系统研究了德国北部三种坡度较小的坡度（脚趾，中坡和上坡位置）受地下水影响的耕作土壤在上层和下层土壤层中不同氧化还原条件下的磷动员。还研究了pH，Al，Fe，Mn和溶解的有机碳（DOC）对P迁移的影响。在所有土壤样品中，初始E _H（+351至+431 mV）和pH（6.5-7.0）均下降（E _H = −280毫伏; 生成浆液时，pH = 4.4）。此后，随着中坡和趾坡土壤中E _H的增加，pH值分别增加到7.1和6.4 。脚趾坡面表层土壤中低E _H下的溶解P的浓度范围为20.8 mg L ^-1，而脚趾中坡中土层中高E _H下溶解的P的浓度为0.69 mg L ^-1。在低E _H下，溶解的Fe（0.31–13.3）和DOC（92–2651）的浓度（mg L ^-1）升高，而在高E _H下降低。低E _H下P动员的增加土壤中的pH和pH可能是由于Fe-（羟基氧化物）的还原性和酸性溶解导致P释放和/或土壤有机质矿化。P在还原条件下的高度动员可能会提高其生物利用度；但是，它可能会增加其在土壤中的损失，特别是在脚趾坡度剖面中。