Soil organic carbon changes and distribution in cultivated and restored grassland soils in Saskatchewan |
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Authors: | J D J Nelson J J Schoenau S S Malhi |
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Affiliation: | (1) Department of Soil Science, University of Saskatchewan, Saskatoon, SK, Canada, S7N 5A8;(2) Agriculture and Agri-Food Canada, P.O. Box 1240, Melfort, SK, Canada, SOE 1AO |
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Abstract: | The impacts of grassland restoration on amounts, forms and distribution of soil organic carbon (SOC) were examined in paired
cultivated and restored grassland catenae of the Missouri Coteau region in south-central Saskatchewan, Canada. Total SOC (0–15 cm
depth) and light fraction organic carbon (LFOC) (0–7.5 cm) contents were determined in paired catenae in upland areas, and
in the surface (0–15 cm) and at depth (>15 cm) in the wetland fringe areas. Mass of SOC was higher in the restored grassland
catenae than in the cultivated equivalents. In both the cultivated and restored grassland catenae at the three sites, footslope
positions consistently had a higher mass of SOC. However, the shoulder positions showed the greatest response in soil C sequestration
to grass seed-down, with a 1.4–2.9 Mg ha−1 year−1 SOC increase apparent over an approximately eight-year period. The mass of LFOC and the proportion of SOC comprised of LFOC
was also higher in the restored grassland, reflective of higher recent C inputs. Rates of C sequestration in the Missouri
Coteau based on SOC differences in the paired comparisons were estimated to be 0.3–2.9 Mg C ha−1 year−1, depending upon site and slope position. In the wetland fringe region of the landscape, the three sites also had higher surface
or subsurface SOC in the grassland restoration. In general, SOC changes at depth (below 15 cm) in the restored grasslands
appeared to be less consistent than changes in SOC in the surface 0–15 cm soil. In conclusion, the findings suggest that a
switch to permanent cover on these soils will significantly increase C sequestered in the soil. |
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Keywords: | Cultivated land Light fraction organic C Restored grassland Soil Total organic C |
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