Application of biochar to rice has shown to elicit positive environmental and agricultural impacts due to its physicochemical properties. However, the relationship between greenhouse gas (GHG) emissions, rice yield, and soil nutrient status under biochar amendment remains unclear. In this study, rice yield and methane (CH4) and nitrous oxide (N2O) emissions were quantified in response to biochar application rate (0, 10, 20, and 40 t ha−1) to early and late subtropical rice cropping systems. We found that application of 10 t of biochar ha−1 to early rice reduced average CH4 emission fluxes, while all biochar application rates diminished average emissions in late rice paddy. Total global warming potential (GWP) and GHG intensity (GHGI) were inherently greater in late rice than early rice cropping. In early rice, GWP and GHGI were found to be similar between soil control, 10 and 20 t of biochar ha−1 treatments, although the largest occurred in the 40 t of biochar ha−1 treatment, whereas in late rice cropping, they were not affected by biochar application rates. Compared to the nil-biochar application, biochar application at varied rates did not affect rice yield. However, compared to 10 t biochar ha−1, increasing biochar application rate to 40 t ha−1 significantly decreased total rice yield (sum of early and late cropping). Generally, application of biochar increased soil salinity and total Fe and Fe2+ content while reducing soil bulk density. Temporal effects of biochar application were noted on CH4 emission flux, soil temperature, and soil Fe2+ and Fe3+ in early rice; and soil temperature, salinity, NH4 +-N, NO3 −-N, and soil Fe2+ and Fe3+ in late rice. This study confirms that the application of biochar at the lower rate of 10 t ha−1 is optimal for maintaining rice yield while reducing GHG emissions. Moreover, the study demonstrates the potential benefit of biochar in sustainable subtropical rice production.

由于其物理化学特性，生物炭在水稻中的应用已显示出对环境和农业的积极影响。然而，生物炭修正下温室气体（GHG）排放、水稻产量和土壤养分状况之间的关系仍不清楚。在这项研究中，对水稻产量和甲烷 (CH 4 ) 和一氧化二氮 (N 2 O) 排放量进行了量化，以响应早晚亚热带水稻种植的生物炭施用率（0、10、20 和 40 t ha -1 ）系统。我们发现在早稻上施用 10 t biochar ha -1可以降低平均 CH 4排放通量，而所有生物炭的施用率都降低了晚稻稻的平均排放量。晚稻的总全球变暖潜势（GWP）和温室气体强度（GHGI）本质上比早稻要高。在早稻中，发现土壤控制、10 和 20 t 生物炭 ha -1处理的 GWP 和 GHGI 相似，尽管最大的发生在 40 t 生物炭 ha -1处理，而在晚稻种植中，它们是不受生物炭施用率的影响。与零生物炭施用相比，不同比例的生物炭施用不影响水稻产量。然而，与 10 t biochar ha -1相比，将 biochar 施用率提高到 40 t ha -1显着降低了水稻总产量（早熟和晚熟之和）。一般来说，生物炭的施用增加了土壤盐分和总Fe和Fe 2+含量，同时降低了土壤容重。施用生物炭对早稻CH 4排放通量、土壤温度和土壤Fe 2+和Fe 3+的时间影响；晚稻土壤温度、盐度、NH 4 + -N、NO 3 - -N、土壤Fe 2+和Fe 3+ 。该研究证实，生物炭的应用率较低，为 10 t ha -1是保持水稻产量同时减少温室气体排放的最佳选择。此外，该研究证明了生物炭在可持续亚热带水稻生产中的潜在益处。