Abstract
Climate change is creating conditions for agriculture to expand northward. For conventional large-scale operations, this will require the conversion of forests to agricultural land in most areas, which has historically been associated with large (30%) losses of soil organic carbon (SOC) and soil degradation. To potentially mitigate these losses, farmers in Northern Ontario, Canada, are incorporating woody residues into their soils during conversion to retain more organic matter on-site, while bringing the land into production faster than conventional conversion approaches. The current study examines the effects of converting forest to agricultural land on soil by comparing SOC storage in the top 45 cm of mineral soil in forests, old (> 50 year) and young (< 10y) conventionally cleared fields, and young fields with mulched forest biomass incorporated into the soil following land clearing in the Great Clay Belt, northeastern Ontario, Canada. There were no statistically significant effects (p > 0.05) of land conversion on SOC storage but there was a redistribution of SOC with depth consistent with soil tillage. Observed trends in mean SOC storage suggest that incorporating woody mulch residues into the soil at the time of conversion may warrant further study as a SOC conservation strategy.