Greenhouse gas emissions and soil bacterial community as affected by biochar amendments after periodic mineral fertilizer applications
Lévesque, V., Rochette, P., Hogue, R., Jeanne, T., Ziadi, N., Chantigny, M.H., Dorais, M., Antoun, H. (2020). Greenhouse gas emissions and soil bacterial community as affected by biochar amendments after periodic mineral fertilizer applications. Biology and Fertility of Soils, [online] 56(7), 907-925. http://dx.doi.org/10.1007/s00374-020-01470-z
Plain language summary
Different strategies for mitigating greenhouse gas (GHG) emissions in agricultural soils have been proposed and the use of biochar, stable carbon (C)-rich material obtained by thermal combustion of biomass, as an amendment could be an effective solution in fertilized soil. The aim of our 338-d laboratory incubation study was to assess the influence of physicochemical properties of two biochars derived from maple barks and produced at 400 °C (M400) or 700 °C (M700) and one derived from pine chips produced at 700 °C (P700) on the potential to mitigate GHG emissions and on the modification in the diversity of bacteria in a clay soil fertilized alone or mixed with compost. Results indicated that the addition of all biochars resulted in lower nitrous oxide (N2O) emissions, a powerful GHG. The lowest emissions of carbon dioxide (CO2) and methane (CH4) were observed with M700 and P700, respectively. The presence of compost influenced the effectiveness of the biochars to mitigate GHG emissions, especially CO2 emissions, due to its high availability of C. Results also showed that compost addition had the highest impact on bacterial diversity and modification of soil properties by maple biochars and induced shifts in the composition of bacterial community. Our study demonstrated that the nature of biochar feedstock can impact soil bacterial diversity by changing soil physicochemical properties and by mitigating GHG emissions. Long-term field trials on different cultivated soils with different biochar amendments are crucial to improve our understanding of biochar microorganism interactions on soil health.
In a 338-d microcosm incubation experiment, greenhouse gas emissions (GHG) and bacterial diversity were studied in a clayey soil amended with 5% (w/w) biochar in the presence or absence of 4% (w/w) peat- and shrimp-based compost used as an additional C source. Two maple biochars produced at 400 °C (M400) or 700 °C (M700) and pine chips produced at 700 °C (P700) were tested. In comparison with soil supplemented or not with compost, the addition of any biochar resulted in lower total cumulative N2O emission (90% to 97%). The low porosity of M400 and M700 increased soil anaerobic conditions and resulted in higher total cumulative CH4 emission compared to the other soil treatments. In addition, the lowest total cumulative CO2 emission was observed with M700, probably due to its low-priming effect on native soil C decomposition. In all treatments, compost addition had the highest impact on both soil bacterial richness and community composition, particularly on bacteria of the class Anaerolineae. At day 338, results showed that modification of soil properties by maple biochars reduced bacterial diversity and induced shifts in the taxonomic composition of their community. In fact, heterotrophic bacteria involved in denitrification, such as genera Haliangium, Hyphomicrobium, Opititus, and Pedomicrobium, increased in abundance in response to the amendment with maple biochars. We conclude that the nature of biochar feedstock can impact soil bacterial diversity by changing soil physicochemical properties, thus influencing C dynamics, porosity, and pH, and by mitigating total cumulative GHG emissions.