Two problems currently facing agriculture are drought and the availability of mineable phosphorus minerals used for fertilization. More frequent and longer drought periods are predicted to threaten agricultural yields in the future. The capacity of soils to hold water is a highly important factor controlling drought stress of plants during the growing phase. High phosphorus availability in soils is also necessary for high agricultural yields, however, over application has also led to a range of environmental problems, foremost being the eutrophication of waterways. Amorphous silica (ASi) has been suggested as one solution to mitigate both water and phosphorus availability. In this work we analyzed the effect of ASi on phosphorus mobility and the soil water storage of a sandy soil. In a lysimeter experiment we found that ASi strongly increased the water storage capacity (WSC) of soils (up to 180% by addition of 3 wt.% ASi). Furthermore, the ASi is in direct competition with phosphorus for sorption sites on iron oxides and other soil minerals increasing nutrient mobilization and increasing potential bioavailability for plants. Following calibration to the lysimeter experiment a process based hydrological model was used to extrapolate experimental results to a sandy agricultural soil with and without ASi for 1 year. For the soil with ASi, the water storage capacities for the yearly scenario were up to 40 kg/m2 higher compared to the untreated soil. Our results suggest that ASi enhances the WSC and phosphorus mobility in soil and that this may be one way to mitigate the predicted climate change related drought stress in sandy soils.

中文翻译：

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无定形二氧化硅控制土壤中的蓄水能力和磷迁移率

目前农业面临的两个问题是干旱和用于施肥的可开采磷矿物的可用性。预计更频繁和更长的干旱期将威胁到未来的农业产量。土壤持水能力是控制植物生长阶段干旱胁迫的一个非常重要的因素。土壤中磷的高可用性对于高农业产量也是必要的，然而，过度施用也导致了一系列环境问题，首先是水道的富营养化。无定形二氧化硅 (ASi) 已被建议作为减少水和磷可用性的一种解决方案。在这项工作中，我们分析了 ASi 对沙质土壤磷迁移率和土壤储水的影响。在蒸渗仪实验中，我们发现 ASi 显着提高了土壤的储水能力 (WSC)（通过添加 3 wt.% ASi 可提高 180%）。此外，ASi 与磷直接竞争铁氧化物和其他土壤矿物质的吸附位点，从而增加养分动员并增加植物的潜在生物利用度。在对蒸渗仪实验进行校准后，使用基于过程的水文模型将实验结果外推到含和不含 ASi 的沙质农业土壤中，为期 1 年。对于含有 ASi 的土壤，与未经处理的土壤相比，每年情景的储水能力高达 40 kg/m2。