Dr Denis Angers1, Dr. Murilo Veloso2, Dr. Cimelio Bayer2
1Agriculture and Agri-food Canada, Quebec, Canada, 2Federal University of Rio Grande do Sul, Porto Alegre, Brazil
Adopting no-tillage (NT) in agro-ecosystems is a recommended measure to enhance C accumulation in soils. However, estimates of potential soil organic C (SOC) storage rates under NT compared to conventional tillage (CT) vary widely, and the reasons for this variability are still unclear. Using a meta-analysis based on global data, we related mean annual precipitation (MAP) and mean annual temperature (MAT) to the potential of NT to accumulate SOC relative to CT. A total of 76 studies were included in the analysis from 5 continents. In all cases, there was a positive effect of NT on SOC in the 0-5 cm soil layer. In non-clayey soils only (<37% clay), SOC accumulation under NT was dependent on MAP and MAT. The relative increase in SOC under NT was best fitted using a hyperbolic curve for MAP and a linear relationship for MAT. SOC accumulation under NT at dry sites (MAP < 600 mm) is likely associated with crop residue accumulation at the soil surface which decomposition is slowed down compared to wetter conditions. At MAP around 700–900 mm, the relative SOC accumulation under NT was close to zero. The greatest effect of NT on SOC was observed at high precipitation and temperature probably due to high productivity (and C input) and accumulation of C at depth under NT. We conclude that at the global scale the response of SOC to NT is partly dependent on climate but in ways that are still largely unclear.
Dr. Denis Angers is a Principal Research Scientist with Agriculture and Agri-Food Canada in Quebec City. He has held Adjunct or Visiting Professorships at Université Laval, McGill University, the University of Brittany, the University of Sydney, and at the Chinese Academy of Agricultural Sciences. His research has focused on soil structure and organic C cycling, with the overall objective of understanding and developing practices to reduce soil degradation and net greenhouse gas emissions through C sequestration. Dr. Angers has been editorial advisor for several international soil science journals and an Editor of the Soil and Environmental Science Dictionary. He is a former President and Fellow of the Canadian Society of Soil Science, a Fellow of the Soil Science Society of America, a Corresponding Member of the French Academy of Agriculture and Doctor Honoris Causa from Agrocampus-Ouest (University of Loire-Brittany).