Liu Xiaoyu, Zheng Jufeng, Zhang Dengxiao, Cheng Kun, Zhou Huimin, Zhang Afeng, Li Lianqing, Joseph Stephen, Smith Pete, Crowley David, Kuzyakov Yakov, Pan Genxing
Institute of Resource, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, China; Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing 210095, China.
Institute of Resource, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, China.
Sci Total Environ. 2016 Jun 1;554-555:259-65. doi: 10.1016/j.scitotenv.2016.02.179. Epub 2016 Mar 5.
Biochar addition to soil has been widely accepted as an option to enhance soil carbon sequestration by introducing recalcitrant organic matter. However, it remains unclear whether biochar will negate the net carbon accumulation by increasing carbon loss through CO2 efflux from soil (soil respiration). The objectives of this study were to address: 1) whether biochar addition increases soil respiration; and whether biochar application rate and biochar type (feedstock and pyrolyzing system) affect soil respiration. Two series of field experiments were carried out at 8 sites representing the main crop production areas in China. In experiment 1, a single type of wheat straw biochar was amended at rates of 0, 20 and 40 tha(-1) in four rice paddies and three dry croplands. In experiment 2, four types of biochar (varying in feedstock and pyrolyzing system) were amended at rates of 0 and 20 tha(-1) in a rice paddy under rice-wheat rotation. Results showed that biochar addition had no effect on CO2 efflux from soils consistently across sites, although it increased topsoil organic carbon stock by 38% on average. Meanwhile, CO2 efflux from soils amended with 40 t of biochar did not significantly higher than soils amended with 20 t of biochar. While the biochars used in Experiment 2 had different carbon pools and physico-chemical properties, they had no effect on soil CO2 efflux. The soil CO2 efflux following biochar addition could be hardly explained by the changes in soil physic-chemical properties and in soil microbial biomass. Thus, we argue that biochar will not negate the net carbon accumulation by increasing carbon loss through CO2 efflux in agricultural soils.
通过添加难降解有机物质，向土壤中添加生物炭已被广泛认为是增强土壤碳固存的一种选择。然而，生物炭是否会通过增加土壤中二氧化碳排放（土壤呼吸）导致的碳损失来抵消净碳积累仍不清楚。本研究的目的是解决：1）添加生物炭是否会增加土壤呼吸；生物炭施用量和生物炭类型（原料和热解系统）是否会影响土壤呼吸。在中国主要作物产区的8个地点进行了两组田间试验。在试验1中，在四块稻田和三块旱地中以0、20和40吨公顷-1的速率添加单一类型的小麦秸秆生物炭。在试验2中，在稻麦轮作下的一块稻田中以0和20吨公顷-1的速率添加四种类型的生物炭（原料和热解系统不同）。结果表明，尽管添加生物炭使表土有机碳储量平均增加了38%，但在各地点添加生物炭对土壤二氧化碳排放均无一致影响。同时，添加40吨生物炭的土壤二氧化碳排放量并不显著高于添加20吨生物炭的土壤。虽然试验2中使用的生物炭具有不同的碳库和物理化学性质，但它们对土壤二氧化碳排放没有影响。添加生物炭后土壤二氧化碳排放很难用土壤物理化学性质和土壤微生物生物量的变化来解释。因此，我们认为生物炭不会通过增加农业土壤中二氧化碳排放导致的碳损失来抵消净碳积累。
