Comparative Measurements of Soil Organic Carbon Content and Greenhouse Gas Fluxes in Nine Shelterbelt and Crop Field Soils.

Aware of the concepts of food security and global climate change, agricultural producers are facing the challenge of producing enough food for an increasing human population and at the same time reducing the environmental impacts associated with agricultural practices. Well-managed shelterbelt agroforestry practices offer opportunities to reduce agricultural greenhouse gas (GHG) emissions and enhance carbon (C) storage. Carbon sequestration and soil-atmosphere exchange of CO₂, CH₄ and N₂O were quantified, and compared to adjacent crop fields, at nine shelterbelt sites across the Boreal Plains and Prairie eco-zones of Saskatchewan. Soil organic C content was measured in both the shelterbelts and adjacent crop fields. Monitoring of CO₂, CH₄ and N₂O fluxes was carried out between spring and fall of 2013 using non-steady state, vented chambers. Soil Organic Carbon (SOC) content was greater in shelterbelts (53.1 Mg ha^-1) than in crop fields (42.9 Mg ha^-1). Seasonal N₂O fluxes were lower in shelterbelts (430.3 g N₂O-N ha^-1 yr^-1) than in crop fields (2190.7 g N₂O-N ha^-1 yr^-1). Methane uptake was greater in shelterbelts (-524.9 g CH₄-C ha^-1 yr^-1) than crop fields (-237.6 g CH₄-C ha^-1 yr^-1). Soil respiration was greater in shelterbelts (3078.9 Kg CO₂-C ha^-1 yr^-1) than crop fields (1638.4 Kg CO₂-C ha^-1 yr^-1) suggesting greater SOC and biological activity in shelterbelts. Differences in GHG emissions due to the effect of shelterbelts are probably a result of modification of local microclimate, organic matter accumulation and root activity. These results suggest that shelterbelt systems have the potential to help mitigate GHG emissions associated with intensive agricultural production.

Keywords: Greenhouse gas, shelterbelt, crop field, carbon dioxide, nitrous oxide, methane