Abstract. In Iran, a significant percentage of agricultural soils are contaminated with a range of potentially toxic elements (PTEs), including Ni, which need to be remediated to prevent their entry into the food chain. Silicon (Si) is a beneficial plant element that has been shown to mitigate the effects of PTEs on crops. Biochar is a soil amendment that sequesters soil carbon and that can immobilize PTEs and enhance crop growth in soils. No previous studies have examined the potentially synergistic effect of Si and biochar on the Ni concentration in soil chemical fractions and the immobilization thereof. Therefore, the aim of this study was to examine the interactive effects of Si and biochar with respect to reducing Ni bioavailability and its corresponding uptake in corn (Zea Mays) in a calcareous soil. A 90 d factorial greenhouse study with corn was conducted. Si application levels were 0 (S0), 250 (S1), and 500 (S2) mg Si kg−1 soil, and biochar treatments (3wt %) including rice husk (RH) and sheep manure (SM) biochars produced at 300 and 500 °C (SM300, SM500, RH300, and RH500) were utilized. At harvest, the Ni concentration in corn shoots, the Ni content in soil chemical fractions, and the release kinetics of DPTA (diethylenetriaminepentaacetic acid)-extractable Ni were determined. Simultaneous utilization of Si and SM biochars led to a synergistic reduction (15 %–36 %) in the Ni content in the soluble and exchangeable fractions compared with the application of Si (5 %–9 %) and SM (5 %–7 %) biochars separately. The application of Si and biochars also decreased the DPTA-extractable Ni and Ni content in corn shoots (by up to 57 %), with the combined application of SM500 + S2 being the most effective. These effects were attributed to the transfer of Ni in soil from more bioavailable fractions to more stable iron-oxide-bound fractions, related to soil pH increase. SM500 was likely the most effective biochar due to its higher alkalinity and lower acidic functional group content which enhanced Ni sorption reactions with Si. The study demonstrates the synergistic potential of Si and SM biochar for immobilizing Ni in contaminated calcareous soils.

中文翻译：

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研究玉米种植后硅和生物炭在受镍污染的钙质土壤中固定镍的协同潜力


摘要。在伊朗，很大一部分农业土壤受到一系列潜在有毒元素 (PTE) 的污染，其中包括镍，需要进行修复以防止其进入食物链。硅 (Si) 是一种有益的植物元素，已被证明可以减轻 PTE 对作物的影响。生物炭是一种土壤改良剂，可以固存土壤碳，并可以固定 PTE 并促进土壤中作物的生长。之前没有研究探讨硅和生物炭对土壤化学成分中镍浓度及其固定的潜在协同效应。因此，本研究的目的是研究硅和生物炭在降低钙质土壤中玉米（Zea Mays）的镍生物利用率及其相应吸收方面的相互作用。对玉米进行了 90 天的阶乘温室研究。硅施用水平为 0 (S0)、250 (S1) 和 500 (S2) mg Si kg−1 土壤，以及生物炭处理 (3wt %)，包括在 300 和 300 ℃下生产的稻壳 (RH) 和羊粪 (SM) 生物炭。使用 500°C（SM300、SM500、RH300 和 RH500）。收获时，测定了玉米芽中的镍浓度、土壤化学成分中的镍含量以及 DPTA（二乙烯三胺五乙酸）可提取的镍的释放动力学。与应用 Si (5 %–9 %) 和 SM (5 %–7 %) 相比，同时使用 Si 和 SM 生物炭导致可溶性和可交换部分中的 Ni 含量协同降低 (15 %–36 %) ）生物炭分开。施用硅和生物炭还降低了玉米芽中 DPTA 可提取的镍和镍含量（最多 57%），其中 SM500 + S2 的联合施用最为有效。 这些影响归因于土壤中镍从生物可利用性更强的部分转移到更稳定的氧化铁结合部分，这与土壤 pH 值的增加有关。 SM500 可能是最有效的生物炭，因为它具有较高的碱度和较低的酸性官能团含量，增强了 Ni 与 Si 的吸附反应。该研究证明了硅和 SM 生物炭在受污染的钙质土壤中固定镍的协同潜力。