Effects of biochar application on soil greenhouse gas fluxes: a meta‐analysis

Abstract

Biochar application to soils may increase carbon (C) sequestration due to the inputs of recalcitrant organic C. However, the effects of biochar application on the soil greenhouse gases (GHGs) fluxes appear variable among many case studies; therefore the efficacy of biochar as a carbon sequestration agent for climate change mitigation remains uncertain. We performed a meta-analysis of 91 published papers with 552 paired comparisons to obtain a central tendency of three main GHG fluxes (i.e., CO 2 , CH 4 , and N 2 O) in response to biochar application. Our results showed that biochar application significantly increased soil CO 2 fluxes by 22.14%, but decreased N 2 O fluxes by 30.92% and did not affect CH 4 fluxes. As a consequence, biochar application may significantly contribute to increased global warming potential (GWP) of total soil GHG fluxes due to the large stimulation of CO 2 fluxes. However, soil CO 2 fluxes were suppressed when biochar was added to fertilized soils, indicating that Accepted ArticleThis article is protected by copyright. All rights reserved. biochar application is unlikely to stimulate CO 2 fluxes in the agriculture sector, in which N fertilizer inputs are common. Responses of soil GHG fluxes mainly varied with biochar feedstock source and soil texture, and the pyrolysis temperature of biochar. Soil and biochar pH, biochar applied rate and latitude also influence soil GHG fluxes, but to a more limited extent.Our findings provide a scientific basis for developing more rational strategies towards widespread adoption of biochar as a soil amendment for climate change mitigation.

Effect of Biochar Application on Soil Carbon Fluxes from Sequential Dry and Wet Cultivation Systems

“…In general, fertilized biochar treatments expelled an elevated amount of CO 2 compared to their non-fertilized counterparts; however, the effect was not significantly proved. This study supports the findings of several scientists in terms of CO 2 emission from upland and paddy fields [13] [15]. They also revealed the fact that, lower biochar application rates (≤10 t·ha −1 ) decrease CO 2 emissions which comply with this experiment at the submerged condition.…”

“…The only fertilized treatment became the principal emitter with 1748 kg·ha −1 followed by the control (1625 kg·ha −1 ). Similar trends of increased soil CO 2 fluxed immediately after flooding were seen by a group of scientist, exceeded pre-flooding values by two-thirds [13] [27]. This increase is unexpected and pulse like.…”

“…[12]. Some laboratory and field trials have showed increased GHG fluxes after biochar incorporation while others showed no significant effect [13]. For instance, application of wheat straw biochar on maize field caused a 12% increase of CO 2 flux while reduced 41.8% of N 2 O and 9.8% of methane emission [14].…”

Returning Tea Pruning Residue and Its Biochar Had a Contrasting Effect on Soil N2O and CO2 Emissions from Tea Plantation Soil

“…The results of meta-analysis conducted by He et al [47] also showed that biochar application significantly increased soil CO 2 fluxes by 22.14%. They discussed that the stimulation of soil CO 2 fluxes might be associated with the higher soil organic C status and the more active soil microbial activities since biochar application enhanced soil organic C and soil microbial biomass C [48].…”

“…The air samples were collected on 0, 1, 2, 3,4,7,11,14,18,25,28,32,36,39,43,47,50,57,63,68,75, 83 and 90 days of incubation. Before sampling, the jars were thoroughly flushed with ambient air and left opened for approximately 30 min to equilibrate with the atmosphere [23].…”