TY - JOUR

T1 - Biochar ageing effects on soil respiration, biochar wettability and gaseous CO2 adsorption

AU - Ojeda, Gerardo

AU - Gil, João M.

AU - Mattana, Stefania

AU - Bachmann, Jörg

AU - Quenea, Katell

AU - Sobral, Abílio J.F.N.

N1 - Funding Information: This study was associated to the Colombian project PS-35-2020 (Universidad Nacional Abierta y a Distancia - UNAD). The authors thank also the Centro de Quimica de Coimbra supported by Fundação para a Ciencia e Tecnologia - FCT (Portugal). The work of CO2 adsorption performed at the CFisUC was supported by the Portuguese Science and Technology Foundation (FCT - Fundação para a Ciência e Tecnologia, I. P., Portugal) through projects UIDB/04564/2020 and UIDP/04564/2020. We want to thank all institutions involved in this study, for facilitating the access to their laboratories and giving support with the corresponding methodologies, equipment and funding resources. Biochar and soil respiration samples were provided from the SOCARRAT project (contract AGL2009-12343 of the Spanish Ministry of Science and Innovation, Spain).

PY - 2024/2

Y1 - 2024/2

N2 - The CO2 emission rates have been continuously incremented during the last decades. To mitigate it, a method to store carbon in terrestrial ecosystems is the addition of biochar to soil. After its application to soil, biochar suffers an ageing process, able to deteriorate its functional properties as soil improver. However, at present, it is not clear how to evaluate biochar ageing. The main aim of this study is to evaluate biochar ageing by determination of temporal changes on (a) soil respiration after biochar addition and (b) the relationship between CO2 adsorption capacity and wettability of biochar as measurable parameters indicating biochar ageing. Results show that 1 month after biochar addition, soil respiration decreased when poplar and pine biochars were applied to bare soils, in the absence of vegetation. One year after biochar addition, this reduction on soil respiration disappeared, evidencing biochar ageing due to decrements on its CO2 adsorption capacity. Compared with fresh biochar, decreased CO2 adsorption capacity of biochar corresponded with enhanced biochar wettability for both biochar types. Its means that poplar and pine biochars, while initially hydrophobic, became hydrophilic after 1 year of its application to soil. It is concluded that changes of biochar CO2 adsorption capacity in time go along with improved wettability as mutually opposed processes. Globally, pine biochar tends to adsorb a higher quantity of CO2 than poplar biochar. The absence of CO2 adsorption of soil without biochar demonstrates the remarkable capacity of both biochars to adsorb carbon dioxide and promote carbon storage in soils.

AB - The CO2 emission rates have been continuously incremented during the last decades. To mitigate it, a method to store carbon in terrestrial ecosystems is the addition of biochar to soil. After its application to soil, biochar suffers an ageing process, able to deteriorate its functional properties as soil improver. However, at present, it is not clear how to evaluate biochar ageing. The main aim of this study is to evaluate biochar ageing by determination of temporal changes on (a) soil respiration after biochar addition and (b) the relationship between CO2 adsorption capacity and wettability of biochar as measurable parameters indicating biochar ageing. Results show that 1 month after biochar addition, soil respiration decreased when poplar and pine biochars were applied to bare soils, in the absence of vegetation. One year after biochar addition, this reduction on soil respiration disappeared, evidencing biochar ageing due to decrements on its CO2 adsorption capacity. Compared with fresh biochar, decreased CO2 adsorption capacity of biochar corresponded with enhanced biochar wettability for both biochar types. Its means that poplar and pine biochars, while initially hydrophobic, became hydrophilic after 1 year of its application to soil. It is concluded that changes of biochar CO2 adsorption capacity in time go along with improved wettability as mutually opposed processes. Globally, pine biochar tends to adsorb a higher quantity of CO2 than poplar biochar. The absence of CO2 adsorption of soil without biochar demonstrates the remarkable capacity of both biochars to adsorb carbon dioxide and promote carbon storage in soils.

KW - Ageing

KW - Biochar

KW - Carbon sequestration

KW - CO adsorption

KW - Contact angle

KW - Soil respiration

UR - http://www.scopus.com/inward/record.url?scp=85187120254&partnerID=8YFLogxK

U2 - 10.1007/s11027-024-10107-7

DO - 10.1007/s11027-024-10107-7

M3 - Article

AN - SCOPUS:85187120254

VL - 29

JO - Mitigation and Adaptation Strategies for Global Change

JF - Mitigation and Adaptation Strategies for Global Change

SN - 1381-2386

IS - 2

M1 - 11

ER -