Tillage method and crop diversification: effect on economic returns and riskiness of cropping systems in a Thin Black Chernozem of the Canadian Prairies

Producers throughout the Canadian Prairies have begun to extend (reducing summerfallow frequency) and diversify their traditional cereal-based rotations by devoting more areas to oilseeds and pulses, and by managing these newer cropping systems with conservation tillage practices. This study examined the economic performance and relative riskiness of monoculture cereal, cereal–oilseed, and cereal–oilseed–pulse rotations, each managed under conventional-, minimum-, and zero-tillage practices over a 12-year period (1987–1998) in the sub-humid Black soil zone of Saskatchewan. These crop rotations included: spring wheat (Triticum aestivum L.)–spring wheat–winter wheat (T. aestivum L.)–fallow (Ws–Ws–Ww–F), spring wheat–spring wheat–flax (Linum usitatissimum L.)–winter wheat (Ws–Ws–Fx–Ww), and spring wheat–flax–winter wheat–field pea (Pisum sativum L.) (Ws–Fx–Ww–P). Annual production costs for the complete rotation systems increased with cropping intensity and cropping diversity (monoculture cereal ($ 249 ha−1) < cereal–oilseed ($ 304 ha−1) < cereal–oilseed–pulse ($ 310 ha−1)); however, costs were not affected by tillage method. The savings in labor, fuel, repair and machinery overhead with minimum- and zero-tillage practices (compared with conventional-tillage) were generally offset by increased expenditures for herbicides. For most grain price scenarios examined, gross returns and net returns were generally highest for Ws–Fx–Ww–P, intermediate for Ws–Ws–Fx–Ww ($ 7–33 ha−1 lower), and lowest for Ws–Ws–Ww–F ($ 35–70 ha−1 lower). Within the mixed rotations, economic returns tended to be higher when managed using minimum- and zero-tillage practices (compared to conventional-tillage), reflecting the higher grain yields they produced. Income variability, or degree of riskiness, was lowest for conservation tillage and the mixed cropping systems. Our findings explain the recent changes in land use practices that have been adopted by most producers in this region.