Soil Carbon and Greenhouse Gas Emissions as Influenced by Soil Erosion within Complex, Cultivated Landscapes in Canada.

In cultivated, topographically complex landscapes, soil erosion results in the redistribution of large amounts of soil. Soil rich in organic carbon (SOC) and nitrogen is lost from the upper slopes and accumulated in the lower slopes. Over the past decade, experiments and observations in Canada have demonstrated that this accumulation of soil influences a variety of biophysical properties and processes, including those relates to SOC and the emission of greenhouse gases in these landscapes.

 Based on column studies, as soil is disturbed (packing, freeze-thaw), emissions increase, but this increase diminishes with time.  In the field, the recurrence of such events on a thickened soil may result in greater emissions, but the depth of tillage and freeze-thaw do not increase as soil accumulates, so buried soil will contribute less over the long-term.

 Based on field studies, at the base of slopes the eroded soils are accumulated resulting in burial to considerable depths (often beyond 50 cm). Dating by ¹³⁷Cs shows that SOC can be effectively sequestered. Nonetheless microbial activity appears to adjust to remain concentrated near surface, where soil environmental conditions are optimum (where roots growth, fertilizer added, soil tilled, minimum distance to O₂ source, maximum distance from water table).

 In areas of soil loss, presumably, the loss of organic-rich soil decreases CO₂ and N₂O emissions since organic-poor subsoil is incorporated into the surface layer degrading soil environmental conditions.

 Consequently, the net impact of soil erosion is presumed to be a reduction in CO₂ and N₂O emissions at the landscape scale.