Impact of crop sequence decisions in the Saskatchewan Parkland

Rotations are constantly being adapted to current economic and management realities. As a result, the crop sequence used tends to depend more on the economic value of particular crop types, principally cereals, oilseeds and pulse crops in the Saskatchewan Parkland, than on the best management practices for optimizing crop productivity. A study was conducted from 1999 to 2001 at Melfort, SK, to assess the effects of growing barley, wheat, canola, flax, and field pea on their own and the other crop stubbles. When a crop was seeded on its own stubble, the poorest grain yield and quality were recorded, a difference that often was related to major pathogens affecting crop productivity. In the first 2 yr of this study, when near normal temperature and precipitation were recorded, little difference was observed in the average crop yield response when any of the crops were seeded on the other broadleaf and cereal stubbles considered in the study. The exception was flax, which performed poorer when seeded on canola than flax stubble, a reflection of the negative impact canola has on arbuscular mycorrhizae populations on subsequent flax in rotation. In 2001, a year with below-normal precipitation and above-average temperature, crops seeded into pea and flax stubble had yields that were 15-40% of the best stubble treatments. Under these drought conditions, field pea was the best crop choice for flax stubble, while wheat was the best choice for pea stubble. The results of this study indicate that for the Saskatchewan Parkland, the lowest risk crop sequence decision is to avoid seeding a crop in its own stubble.