Annual crop production in the Canadian prairies is undergoing significant change. Traditional monoculture cereal cropping systems, which rely on frequent summer‐fallowing and use of mechanical tillage, are being replaced by extended and diversified crop rotations together with the use of conservation tillage (minimum and zero‐tillage) practices. This paper reviews the findings of western Canadian empirical studies that have examined the economic forces behind these land use and soil tillage changes. The evidence suggests that including oilseed and pulse crops in the rotation with cereal grains contributes to higher and more stable net farm income in most soil–climatic regions, despite a requirement for increased expenditures on purchased inputs. In the very dry Brown soil zone and drier regions of the Dark Brown soil zone where the production risk with stubble cropping is high, the elimination of summer fallow from the cropping system may not be economically feasible under present and near‐future economic conditions. The use of conservation tillage practices in the management of mixed cropping systems is highly profitable in the more moist Black and Gray soil zones (compared with conventional mechanical tillage methods) because of significant yield advantages and substantial resource savings that can be obtained by substituting herbicides for the large amount of tillage that is normally used. However, in the Brown soil zone and parts of the Dark Brown soil zone, the short‐term economic benefits of using conservation tillage practices are more marginal and often less profitable than comparable conventional tillage practices.
A goal in sustainable agriculture is to use fossil fuel energy more efficiently in crop production. This 12-year study investigated effects of two crop rotations and two crop production systems (organic versus conventional management) on energy use, energy output and energy-use efficiency. The grain-based rotation included wheat (Triticum aestivum L.)-pea (Pisum sativum L.)-wheat-flax (Linum usitatissimum L.), while the integrated rotation included wheat-alfalfa (Medicago sativa L.)-alfalfa-flax. Energy use was 50% lower with organic than with conventional management, and approximately 40% lower with integrated than with the grain-based rotation. Energy use across all treatments averaged 3420 MJ ha -1 yr -1 . Energy output (grain and alfalfa herbage only) across treatments averaged 49,947 MJ ha -1 yr -1 and was affected independently by production system and crop rotation. Energy output in the integrated rotation was three times that of the grain-based rotation; however, this difference was largely due to differences in crop type (whole plant alfalfa compared with grain seed). Energy output was 30% lower with organic than with conventional management. Energy efficiency (output energy/input energy) averaged to 17.4 and was highest in the organic and integrated rotations. A significant rotation by production system interaction (P < 0.05) indicated that energy efficiency increases due to crop input reduction (i.e., shift from conventional to organic management) were greater in the integrated than in the grain-based rotation. Greater energy efficiency in the integrated rotation under organic management was attributed to the fact that the forage component was less sensitive to chemical input removal than grain crops.
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