This paper critically reviewed the current knowledge and challenges of rice husk biochar (RHB) production and its effects on soil properties, plant growth, immobilization of heavy metals, reduction of nutrient leaching and mitigation of greenhouse gas emissions. The characteristics of RHBs produced at various pyrolysis temperatures were discussed and compared to biochars derived from other agro- industrial wastes. RHBs produced at higher pyrolysis temperatures show lower hydrogen/carbon ratio, which suggests the presence of higher aromatic carbon compounds. The increase of pyrolysis temperature also results in production of RHBs with higher ash content, lower yield and higher surface area. RHB usually has higher silicon and ash contents and lower carbon content compared to biochars derived from other feedstocks at the same pyrolysis conditions. Although it depends on soil type, RHB application can improve soil organic carbon content, cation exchange capacity, available K concentration, bulk density and microbial activity. The effect of RHB on soil aggregation mainly depends on soil texture. The growth of different crops is also enhanced by application of RHB. RHB addition to soil can immobilize heavy metals and herbicides and reduce their bioavailability. RHB application shows a significant capacity in reduction of nitrate leaching, although its magnitude depends on the biochar application rate and soil biogeochemical characteristics. Use of RHB, especially in paddy fields, shows a promising mitigation effect on greenhouse gas (CH₄, CO₂ and N₂O) emissions. Although RHB characteristics are also related to other factors such as pyrolysis heating rate and residence time, its performance for specific applications (e.g. carbon sequestration, pH amendment) can be manipulated by adjusting the pyrolysis temperature. More research is needed on long-term field applications of RHB to fully understand the advantages and disadvantages of RHB as a soil amendment.

本文批判性地回顾了稻壳生物炭 (RHB) 生产的当前知识和挑战及其对土壤特性、植物生长、重金属固定、减少养分流失和减缓温室气体排放的影响。讨论了在不同热解温度下生产的 RHB 的特性，并将其与其他农业工业废物衍生的生物炭进行了比较。在较高热解温度下产生的 RHB 显示出较低的氢/碳比，这表明存在较高的芳香碳化合物。热解温度的升高也导致产生具有更高灰分、更低产率和更高表面积的RHB。在相同的热解条件下，与衍生自其他原料的生物炭相比，RHB 通常具有较高的硅和灰分含量以及较低的碳含量。虽然这取决于土壤类型，但施用 RHB 可以提高土壤有机碳含量、阳离子交换能力、有效钾浓度、容重和微生物活性。RHB对土壤团聚的影响主要取决于土壤质地。施用RHB也促进了不同作物的生长。向土壤中添加 RHB 可以固定重金属和除草剂并降低其生物利用度。RHB 施用显示出显着的减少硝酸盐浸出的能力，尽管其大小取决于生物炭施用率和土壤生物地球化学特征。RHB 的使用，尤其是在稻田中，显示出对温室气体（CH 体积密度和微生物活性。RHB对土壤团聚的影响主要取决于土壤质地。施用RHB也促进了不同作物的生长。向土壤中添加 RHB 可以固定重金属和除草剂并降低其生物利用度。RHB 施用显示出显着的减少硝酸盐浸出的能力，尽管其大小取决于生物炭施用率和土壤生物地球化学特征。RHB 的使用，尤其是在稻田中，显示出对温室气体（CH 体积密度和微生物活性。RHB对土壤团聚的影响主要取决于土壤质地。施用RHB也促进了不同作物的生长。向土壤中添加 RHB 可以固定重金属和除草剂并降低其生物利用度。RHB 施用显示出显着的减少硝酸盐浸出的能力，尽管其大小取决于生物炭施用率和土壤生物地球化学特征。RHB 的使用，尤其是在稻田中，显示出对温室气体（CH RHB 施用显示出显着的减少硝酸盐浸出的能力，尽管其大小取决于生物炭施用率和土壤生物地球化学特征。RHB 的使用，尤其是在稻田中，显示出对温室气体（CH RHB 施用显示出显着的减少硝酸盐浸出的能力，尽管其大小取决于生物炭施用率和土壤生物地球化学特征。RHB 的使用，尤其是在稻田中，显示出对温室气体（CH₄、CO ₂和N ₂ O)排放。尽管 RHB 特性还与其他因素有关，例如热解加热速率和停留时间，但可以通过调整热解温度来控制其在特定应用（例如碳封存、pH 修正）中的性能。需要对 RHB 的长期田间应用进行更多研究，以充分了解 RHB 作为土壤改良剂的优缺点。