Response of soil carbon dioxide fluxes, soil organic carbon and microbial biomass carbon to biochar amendment: a meta‐analysis

Abstract

Biochar as a carbon-rich coproduct of pyrolyzing biomass, its amendment has been advocated as a potential strategy to soil carbon (C) sequestration. Updated data derived from 50 papers with 395 paired observations were reviewed using meta-analysis procedures to examine responses of soil carbon dioxide (CO 2 ) fluxes, soil organic C (SOC), and soil microbial biomass C (MBC) contents to biochar amendment. When averaged across all studies, biochar amendment had no significant effect on soil CO 2 fluxes, but it significantly enhanced SOC content by 40% and MBC content by 18%. A positive response of soil CO 2 fluxes to biochar amendment was found in rice paddies, laboratory incubation studies, soils without vegetation, and unfertilized soils. Biochar amendment significantly increased soil MBC content in field studies, N-fertilized soils, and soils with vegetation. Enhancement of SOC content following biochar amendment was the greatest in rice paddies among different land-use types. Responses of soil CO 2 fluxes and MBC to biochar amendment varied with soil texture and pH. The use of biochar in combination with synthetic N fertilizer and waste compost fertilizer led to the greatest increases in soil CO 2 fluxes and MBC content, respectively. Both soil CO 2 fluxes and MBC responses to biochar amendment decreased with biochar application rate, pyrolysis temperature, or C/N ratio of biochar, while each increased SOC content enhancement. Among different biochar feedstock sources, positive responses of soil CO 2 fluxes and MBC were the highest for manure and crop residue feedstock sources, respectively. Soil CO 2 flux responses to biochar amendment decreased with pH of biochar, while biochars with pH of 8.1-9.0 had the greatest enhancement of SOC and MBC contents. Therefore, soil properties, land-use type, agricultural practice, and biochar characteristics should be taken into account to assess the practical potential of biochar for mitigating climate change.

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 increase in CO 2 production upon biochar amendment was most likely due to mineralization of labile C fractions added with the biochar [49,50].…”

Change in active microbial community structure, abundance and carbon cycling in an acid rice paddy soil with the addition of biochar

“…It is uncertain whether the addition of biochar to soil increases (Castaldi et al ., ; Jones et al ., ; Mitchell et al ., ), does not affect (Zavalloni et al ., ) or even decreases (Lu et al ., ) soil respiration. Although these differences depend on either soil or biochar conditions or both (Liu et al ., ), changes in soil microbial communities might underpin the variation in soil respiration under biochar (Lehmann et al ., ). Jiang et al .…”

Responses of soil carbon sequestration to climate‐smart agriculture practices: A meta‐analysis

“…Although these CSA management practices have been widely used to enhance soil health (e.g., Denef, Zotarelli, Boddey, & Six, 2007;Fungo et al, 2017;Thomsen & Christensen, 2004;Weng et al, 2017), their effects on SOC sequestration are variable and highly dependent on experiment designs and site-specific conditions such as climate and soil properties (Abdalla, Chivenge, Ciais, & Chaplot, 2016;Liu et al, 2016;Paustian et al, 2016;Poeplau & Don, 2015). The potential to sequester soil carbon varies greatly among CSA practices, which has not been well addressed.…”

“…The potential to sequester soil carbon varies greatly among CSA practices, which has not been well addressed. Also, most prior quantitative research focused on the effects of a single CSA practice on SOC (e.g., Abdalla et al, 2016;Liu et al, 2016;Poeplau & Don, 2015), very few studies estimated the combined effects of diverse CSA and conventional management practices. Also, most prior quantitative research focused on the effects of a single CSA practice on SOC (e.g., Abdalla et al, 2016;Liu et al, 2016;Poeplau & Don, 2015), very few studies estimated the combined effects of diverse CSA and conventional management practices.…”