Effects of crop inputs, diversity, environment, and terrain on yield in an 18-yr study in the semi-arid Canadian prairies

The majority of Canada’s grains and oilseeds are produced in Canadian Prairies. A long-term field experiment was conducted in 1994 - 2013 at Scott, Saskatchewan, Canada. The goal of the experiment was to assess the interaction of cropping diversity and agricultural inputs on crop production in the region. We assessed effects of agricultural inputs and cropping diversity in the context of growing season precipitation, growing degree days/heat units, and field topography on the yield of spring wheat, barley, and canola. This analysis was necessary to show how combinations of different tillage systems, cropping diversities, as well as precipitation, temperature, and topography affect crop yield in the field. Agricultural inputs were organic, minimum, and conventional tillage. Cropping diversities were wheat-fallow, diversified annual grains, and diversified annual perennials. Precipitation in April and June were identified as primary, and inputs, crop diversity, and field topography (slope, elevation) as secondary yield defining factors in this experiment. The analysis also showed that yield was highest in the conventional and minimum, and lower in the organic system. In addition, crop yield was highest in conventional tillage under diversified annual grains and perennials, and in minimum tillage under wheat-fallow rotations, than in any other combination of tillage and diversity. We concluded that precipitation, temperature/heat units and field topography elements were important yield defining factors in this study. These factors should be assessed together when analyzing impacts of tillage systems and cropping diversity on yield, even in a relatively flat landscape.