Key Laboratory of Humid Subtropical Eco-Geographical Process, Ministry of Education, Fujian Normal University, Fuzhou, 350007, China.
CSIC, Global Ecology Unit, CREAF-CSIC-UAB, Bellaterra, 08193, Barcelona, Catalonia, Spain; CREAF, Cerdanyola del Vallès, 08193, Catalonia, Spain.
Environ Pollut. 2021 Oct 15;287:117565. doi: 10.1016/j.envpol.2021.117565. Epub 2021 Jun 16.
Biochar is often applied to paddy soils as a soil improver, as it retains nutrients and increases C sequestration; as such, it is a tool in the move towards C-neutral agriculture. Nitrogen (N) fertilizers have been excessively applied to rice paddies, particularly in small farms in China, because N is the major limiting factor for rice production. In paddy soils, dynamic changes in iron (Fe) continuously affect soil emissions of methane (CH) and carbon dioxide (CO); however, the links between Fe dynamics and greenhouse gas emissions, dissolved organic carbon (DOC), and rice yields following application of biochar remain unclear. The aims of this study were to examine the effects of two rates of nitrogen (N)-enriched biochar (4 and 8 t ha y) on paddy soil C emissions and storage, rice yields, and Fe dynamics in subtropical early and late rice growing seasons. Field application of N-enriched biochar at 4 and 8 t ha increased C emissions in early and late rice, whereas application at 4 t ha significantly increased rice yields. The results of a culture experiment and a field experiment showed that the application of N-enriched biochar increased soil Feconcentration. There were positive correlations between Feconcentrations and soil CO, CH, and total C emissions, and with soil DOC concentrations. On the other way around, these correlations were negative for soil Feconcentrations. In the soil culture experiment, under the exclusion of plant growth, N-enriched biochar reduced cumulative soil emissions of CH and CO. We conclude that moderate inputs of N-rich biochar (4 t ha) increase rice crop yield and biomass, and soil DOC concentrations, while moderating soil cumulative C emissions, in part, by the impacts of biochar on soil Fe dynamics. We suggest that water management strategies, such as dry-wet cycles, should be employed in rice cultivation to increase Fe oxidation for the inhibition of soil CH and CO production. Overall, we showed that application of 4 t ha of N-enriched biochar may represent a potential tool to improve sustainable food production and security, while minimizing negative environmental impacts.
生物炭通常作为土壤改良剂应用于稻田，因为它可以保留养分并增加碳封存；因此，它是实现碳中性农业的工具。氮肥在中国，特别是在小农户的稻田中，被过度施用，因为氮是水稻生产的主要限制因素。在稻田土壤中，铁（Fe）的动态变化不断影响土壤甲烷（CH）和二氧化碳（CO）的排放；然而，生物炭施用后，Fe 动态与温室气体排放、溶解有机碳（DOC）和水稻产量之间的联系尚不清楚。本研究旨在探讨两种富氮生物炭（4 和 8 t ha）对亚热带早稻和晚稻生长季节稻田土壤 C 排放和储存、水稻产量以及 Fe 动态的影响。富氮生物炭在早稻和晚稻的田间施用量为 4 和 8 t ha 时增加了 C 排放，而施用量为 4 t ha 时显著增加了水稻产量。培养实验和田间实验的结果表明，施富氮生物炭增加了土壤 Fe 浓度。土壤 Fe 浓度与土壤 CO、CH 和总 C 排放以及土壤 DOC 浓度呈正相关，与土壤 Fe 浓度呈负相关。在土壤培养实验中，在排除植物生长的情况下，富氮生物炭减少了 CH 和 CO 的土壤累积排放量。我们得出结论，适度施用富氮生物炭（4 t ha）可以增加水稻作物产量和生物量，增加土壤 DOC 浓度，同时通过生物炭对土壤 Fe 动态的影响，适度调节土壤累积 C 排放。我们建议在水稻种植中采用干湿循环等水管理策略，以增加 Fe 氧化，从而抑制土壤 CH 和 CO 的产生。总的来说，我们表明，施用 4 t ha 的富氮生物炭可能是一种潜在的工具，可以在最小化负面环境影响的同时，提高可持续粮食生产和安全。
