Thus far, a series of field experiments have been conducted across the globe to investigate the effects of biochar on crop productivity. However, a comprehensive evaluation of the improvement potential of crop yield, water use, and relevant underlying drivers after adding biochar remains lacking. A synthesis based on global field experiments was conducted herein to investigate the efficacy of biochar in crop-yield and water-use improvement, taking a range of potential impacting factors into account. The results showed that biochar significantly increased crop yield and crop water productivity (WPc), by 11.2 % and 14.8 %, respectively, but caused a significant decline (1.8 %) in crop evapotranspiration (ETc). The highest crop-yield improvement was reached at an application rate of > 20 t ha−1 in the initial year after adding biochar. Low C/N, high pyrolysis temperature, low pH, and wood-based raw materials were found to be beneficial biochar properties for increasing crop production. Biochar generally performed better in soils of low pH and low fertility, especially in hot and humid climates. There was a higher increase in crop yield for corn compared with those for wheat and rice. In addition, changes in WPc were generally commensurate with those of crop yield in most scenarios. Conditions beneficial for crop-yield improvement tend to result in a higher increase in WPc through their effects on ETc. Overall, this study illustrates that crop yield improvement is closely related to improvements in both soil fertility and water use. The latter represents an important factor related to crop growth and productivity through the regulation of evaporation and transpiration after biochar amendment. Despite the promising performance of biochar in promoting crop yield and WPc, a further challenge involves ways to maximize the effects of biochar across global croplands by properly considering the impacting factors during the process of policy design and implementation.

中文翻译：

---

通过生物炭应用最大限度地提高作物产量和水生产力：田间实验的全球综合


到目前为止，已经在全球范围内进行了一系列田间实验，以研究生物炭对作物生产力的影响。然而，仍然缺乏对添加生物炭后作物产量、水分利用和相关潜在驱动因素的改进潜力的全面评估。本文进行了基于全球田间实验的综合研究，以研究生物炭在提高作物产量和水分利用方面的功效，同时考虑到一系列潜在的影响因素。结果表明，生物炭显著提高了作物产量和作物水分生产率 （WPc），分别提高了 11.2% 和 14.8%，但导致作物蒸散量 （ETc） 显著下降 （1.8%）。在添加生物炭后的第一年，施用量为 > 20 t ha-1，作物产量提高最高。研究发现，低 C/N、高热解温度、低 pH 值和木质原料是提高作物产量的有益生物炭特性。生物炭通常在低 pH 值和低肥力的土壤中表现更好，尤其是在炎热潮湿的气候中。与小麦和水稻相比，玉米的作物产量增加幅度更大。此外，在大多数情况下，WPc 的变化通常与作物产量的变化相称。有利于作物产量提高的条件往往通过其对 ETc 的影响导致 WPc 的增加更高。总体而言，本研究表明，作物产量的提高与土壤肥力和水利用的改善密切相关。后者通过调节生物炭改性后的蒸发和蒸腾作用，代表了与作物生长和生产力相关的重要因素。 尽管生物炭在促进作物产量和 WPc 方面表现出色，但另一个挑战涉及通过在政策设计和实施过程中适当考虑影响因素来最大限度地发挥生物炭在全球农田中的作用的方法。