Phosphogypsum (PG) is an acid by-product generated during the breakdown of phosphate ore in the presence of sulfuric acid and has been used as a soil amendment, i.e., fertilizer, in most parts of the world. PG application can improve some soil properties and increase crop yields. However, PG application in agriculture threatens agroecological systems and food safety because of the high amounts of environmentally and biologically available potentially toxic elements (PTEs) in PG. Recently, biochar has been found to strongly immobilize and adsorb PTEs as well as suppress PTE phytoavailability. Hence, in this context, bench-scale batch and column experiments were performed to test the availability of PTEs in PG under different pyrolysis temperatures and different percentages of rice husk biochar (RHB). Subsequently, pot experiments were performed to test the effect of RHB addition on the PTE concentrations in crops when PG was added to different types of soil, and the effect of the RHB and PG combination on crop yield was determined. The batch and column experimental results showed that the pyrolysis temperature and biochar dose significantly reduced the PTE concentrations in PG because the biochar physicochemical properties, components, and types of functional groups, which were analysed by XRF, XRD and FTIR, were mainly controlled by temperature. The preparation temperature (600°C) and applied dose (60%, w/w) of RHB were optimized through a mixed-effect model. Furthermore, the mechanism underlying P, F and heavy metals in PG leachates adsorbed onto biochar was determined by XPS analysis, which showed that surface ions and different functional groups played a dominant role through precipitation and complexation. Compared to the control, application of the combination to loam soil or sand significantly increased (56.04% and 604.66%, respectively) crop yield. The combination significantly decreased PTE concentrations (As, F, Cd, and Pb by 39, 41, 75, and 86%, respectively, in water spinach and by 100%, 64%, 75%, and 88%, respectively, in asparagus lettuce) in edible parts of crops compared to PG treatment only. Moreover, RHB+PG reduced pollution to the surrounding environment by decreasing the PTE contents in the leachate. These findings suggest that the improved effectiveness of the combination was greater in sand because of its weak buffering ability, and the RHB and PG combination can be a useful and safe soil amendment to provide good guidance for waste management and comprehensive utilization of waste.

磷石膏（PG）是在硫酸存在下磷酸盐矿石分解过程中产生的酸副产物，在世界上大多数地区已用作土壤改良剂，即肥料。PG的施用可以改善土壤的某些特性并增加农作物的产量。然而，由于PG中大量的环境和生物可用的潜在有毒元素（PTE），PG在农业中的应用威胁着农业生态系统和食品安全。近来，已发现生物炭强烈地固定和吸附PTE并抑制PTE的植物利用率。因此，在这种情况下，进行了台式规模的批处理和柱实验，以测试在不同的热解温度和不同百分比的稻壳生物炭（RHB）下PG中PTE的可用性。后来，进行盆栽试验以测试将PG添加到不同类型的土壤中时，添加RHB对作物中PTE浓度的影响，并确定了RHB和PG组合对作物产量的影响。批处理和柱实验结果表明，热解温度和生物炭剂量显着降低了PG中的PTE浓度，因为通过XRF，XRD和FTIR分析的生物炭理化性质，组分和官能团类型主要受温度控制。 。通过混合效应模型优化了RHB的制备温度（600°C）和施用剂量（60％，w / w）。此外，通过XPS分析确定了PG渗滤液吸附到生物炭上的P，F和重金属的潜在机理，表明表面离子和不同的官能团通过沉淀和络合作用起主导作用。与对照相比，将组合物施用到壤土或沙子上可显着提高作物产量（分别为56.04％和604.66％）。该组合显着降低了菠菜中PTE的浓度（As，F，Cd和Pb分别降低了39％，41％，75％和86％，而芦笋中分别降低了100％，64％，75％和88％）与仅使用PG处理相比）。此外，RHB + PG通过减少渗滤液中的PTE含量减少了对周围环境的污染。这些发现表明，由于砂土的缓冲能力较弱，因此砂土组合的改进效果更好，