Dynamics of soil-derived greenhouse gas emissions from shelterbelts under elevated soil moisture conditions in a semi-arid prairie environment
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Soil moisture is known to be a major control of greenhouse gas (GHG) emissions from agricultural soils. However, there is little data regarding GHG exchange from the organic matter-rich soils characteristic of shelterbelts—especially under elevated soil moisture conditions. In the present study, we quantified CO2, CH4 and N2O fluxes from shelterbelts under elevated soil moisture (irrigated) and semi-arid (rainfed) conditions. Studies were carried out at the Canada-Saskatchewan Irrigation Diversification Centre (CSIDC) near Outlook, Saskatchewan. Non-steady state vented chambers were used to monitor soil GHG fluxes from three shelterbelts in 2013 and 2014. The shelterbelts consisted of a single row of caragana with a north–south orientation and a single row of Scots pine with either a north–south or east–west orientation. Each shelterbelt was divided into two areas based on whether or not it received irrigation. During the 2-year study period, N2O emissions from the irrigated shelterbelts (IR-SB) (0.93 kg N2O-N ha−1) were significantly greater than those from the rainfed shelterbelts (RF-SB) (0.49 kg N2O-N ha−1). Soil CH4 oxidation was significantly lower in the IR-SB compared to the RF-SB (−0.85 and −1.20 kg CH4-C ha−1, respectively). Irrigation activities stimulated CO2 production/emission in 2014, but had no effect on CO2 emissions during the much drier 2013 season. Correlation analyses indicate a strong dependence of CO2 and CH4 fluxes on soil moisture in both IR-SB and RF-SB sites. There was a significant relationship between N2O emissions and soil moisture for the IR-SB sites in 2013; however, no such relationship was observed in either the IR-SB or RF-SB sites in 2014. Our study suggests that changes in precipitation patterns and soil moisture regime due to climate change could affect soil-atmosphere exchange of GHGs in shelterbelts; however, elevated soil moisture effect on GHG emissions will depend on the availability of N and C in the shelterbelts.
KeywordsShelterbelt Agroforestry Soil moisture Greenhouse gas N-fixation Irrigation Nitrous oxide Methane Carbon dioxide
Funding was provided by Agriculture and Agri-Food Canada (AAFC)’s Agricultural Greenhouse Gases Program (AGGP). Additional financial support was provided by the Saskatchewan Ministry of Agriculture Strategic Research Program—Soils and Environment. We are grateful to M. Jones, L. Jordan, D. Jackson, M. Cooke, F. Krijnen and D. Richman for their assistance during field and laboratory work.
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