Improving rice quality through biochar application in China: A meta-analysis.

Purpose: This research investigates the effects of biochar application on rice quality through a comprehensive meta-analysis, aiming to elucidate the ambiguous impacts of biochar on rice quality indicators and providing a comprehensive quantitative evaluation to inform sustainable agricultural practices and the practical application of biochar in rice cultivation.

Design/methodology/approach: Utilizing a systematic meta-analysis, this study extracts 934 pairs of observations from 28 different studies. It integrates data to assess the overarching impact of biochar on rice quality, with a specific focus on ten essential quality indicators: brown rice rate, milled rice rate, head rice rate, chalky rice rate, degree of chalkiness, length-width ratio, amylose content, protein content, gel consistency, and eating quality score. This approach enables a detailed evaluation of how biochar application influences these critical aspects of rice quality.

Findings: The meta-analysis reveals that biochar application notably enhances the processing, appearance, and eating quality score of rice, evidenced by improvements in the brown rice rate by 0.5%, milled rice rate by 1.7%, head rice rate by 6.2%, length-width ratio by 1.4%, and eating quality score by 2.6%. It also substantially reduces the chalky rice rate by 11.1% and the degree of chalkiness by 12.9%. However, the impacts on nutritional indicators, such as amylose content, gel consistency, and protein content, were found to be statistically insignificant. The most favorable effects were observed in heavy loam soil, alkaline soil(pH ≥ 7.5), soil organic content (SOM)＜10 g kg^-1, biochar with a pH range of 7-8, high-temperature biochar (≥ 400 °C), and biochar derived from husk and shell.

Practical implications: This study highlights biochar's potential to improve rice quality, particularly in terms of processing and appearance, without negatively affecting its nutritional profiles. These findings support the utilization of biochar in rice production to improve quality and provide valuable insights for the development of sustainable agricultural practices and effective biochar application guidelines.

Originality/value: This study represents a pioneering effort in agricultural science by systematically quantifying the impact of biochar on key rice quality indicators. It sheds light on the positive effects of biochar in enhancing various aspects of rice quality, underscoring its vital role in promoting sustainable agricultural practices. Through this meta-analysis, the study establishes a foundation for effective biochar usage guidelines in rice cultivation, offering substantial insights and paving new avenues for research into biochar's application in agriculture.