Dynamics of soil-derived greenhouse gas emissions from shelterbelts under elevated soil moisture conditions in a semi-arid prairie environment

Abstract

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.