16 research outputs found
Biochar built soil carbon over a decade by stabilizing rhizodeposits
Biochar can increase the stable C content of soil. However, studies on the longer-term role of plantâsoilâbiochar interactions and the consequent changes to native soil organic carbon (SOC) are lacking. Periodic 13CO2 pulse labelling of ryegrass was used to monitor belowground C allocation, SOC priming, and stabilization of root-derived C for a 15-month periodâcommencing 8.2 years after biochar (Eucalyptus saligna, 550â°C) was amended into a subtropical ferralsol. We found that field-aged biochar enhanced the belowground recovery of new root-derived C (13C) by 20%, and facilitated negative rhizosphere priming (it slowed SOC mineralization by 5.5%, that is, 46âg CO2-C mâ2 yrâ1). Retention of root-derived 13C in the stable organo-mineral fraction (<53âÎŒm) was also increased (6%, P < 0.05). Through synchrotron-based spectroscopic analysis of bulk soil, field-aged biochar and microaggregates (<250âÎŒm), we demonstrate that biochar accelerates the formation of microaggregates via organo-mineral interactions, resulting in the stabilization and accumulation of SOC in a rhodic ferralsol.Zhe (Han) Weng, Lukas Van Zwieten, Bhupinder Pal Singh, Ehsan Tavakkoli, Stephen Joseph, Lynne M. Macdonald, Terry J. Rose, Michael T. Rose, Stephen W. L. Kimber, Stephen Morris, Daniel Cozzolino, Joyce R. Araujo, Braulio S. Archanjo and Annette Cowi