Nelson, A.G.¹* and Froese, J.C.¹

Little, if any, research has been conducted in Canada looking at soil erosion risk on organic farms. Despite this, organic farming systems are criticized by proponents of conservation tillage as contributing to soil erosion through the increased use of tillage for weed control. It is known that crop rotations can be used to ameliorate a variety of agronomic problems encountered in farming systems, including soil erosion. The objective of this study is to examine the effect of crop rotation (annual-, biennial-, or perennial-containing rotations) and management (organic or conventional) on erosion risk within selected Canadian provinces. Three long-term rotation studies (Lethbridge, AB; Scott, SK and Glenlea, MB) were sampled to compare wet (WAS) and dry aggregate stability (DAS), as well as organic carbon (C) content on organic and conventional plots. Rotation significantly affected organic C at Scott; the rotation containing perennials had the highest level of organic C. At Glenlea, organic C was affected by management; C levels were higher in the conventional plots. At the Scott study, conventional plots had higher WAS, while organic management resulted in higher WAS at the Glenlea study. Rotation effect also gave conflicting results for DAS over sites and years. It was concluded that neither management (organic or conventional), or rotation solely affect soil erosion risk. Erosion risk is most likely affected by the combination of crop rotation, tillage and soil conservation practices within a particular climate, soil type and topography.

¹ University of Manitoba, Winnipeg, MB
*Correspondence: umnels06@cc.umanitoba.ca