Residue decomposition and soil carbon priming in three contrasting soils previously exposed to elevated CO 2

Abstract

The effects of elevated atmospheric carbon dioxide (eCO 2 ) on belowground processes are known to occur directly and indirectly via plants. However, the long-term impact of eCO 2 on biochemical properties and processes of agricultural soils in the absence of plants is unclear. The current study investigated whether residue decomposition and the subsequent ‘priming effect’ on soil organic C (SOC) mineralisation were altered in three contrasting soils previously exposed to either ambient CO 2 (aCO 2 ; 390 ppm) or eCO 2 (550 ppm) using free-air CO 2 enrichment (FACE) for 4 years. Surface soils (0–2 cm) of calcisol, luvisol and vertisol were amended (0.5% w w −1 ) with 13 C-labelled field pea (P..