Features Production Research
Trials show canola, alfalfa best rotation crops for potatoes in Manitoba

Crop rotation trials based near
Brandon, Manitoba, indicate canola and alfalfa are the most beneficial
crops to use in rotation with potatoes.

Rotating potato crops with canola resulted in a trend towards a higher than average gross, plus marketable (more than two inches) and bonus (more than 10 ounces) tuber yields. But the potato and canola rotation didn’t do as well in disease prevention.

Crop rotation trials based near Brandon, Manitoba, indicate canola and alfalfa are the most beneficial crops to use in rotation with potatoes.

Dr. Ramona Mohr, a sustainable systems agronomist at Agriculture and Agri-Food Canada’s Brandon Research Centre, has spent more than eight years researching production systems. When it comes to yield and quality, she reports a two year rotation of a potato crop followed by canola or a four year rotation of potatoes, canola (underseeded to alfalfa) and followed by two years of alfalfa, yield the best results.

“The processing potato industry has expanded rapidly in Manitoba in recent years,” Mohr says. “But much of the agronomic information currently available to growers is based on research from other areas. Our goal is to identify crop rotations that minimize yield and quality losses due to disease and weeds while maintaining soil quality under Manitoba conditions.”

The research has been conducted in the Carberry area. Mohr and her colleagues experimented with six rotations:
•     potato/canola and potato/wheat over two years,
•     potato/canola/wheat and potato/oats/wheat over three years, and
•    potato/wheat/canola/wheat and potato/canola/alfalfa/alfalfa over four years.

Rotating potato crops with alfalfa also resulted in a trend towards a higher than average gross, plus marketable (more than two inches) and bonus (more than 10 ounces) tuber yields, as was also seen with canola rotations.

For yield and quality, Mohr reports that no single rotation consistently and substantially outperformed the others in terms of gross yield. But, averaged out over the eight years of research done to date, the potato/canola and potato/canola/ alfalfa/alfalfa rotations demonstrate a trend towards a higher than average gross, marketable (more than two inches) and bonus (more than 10 ounces) tuber yields.

The potato-canola rotation however didn’t do as well in disease prevention, Mohr adds. She reports that the two-year potato/canola and potato/wheat rotations registered the highest incidence of
black leg, rhizoctonia stem canker and vascular diseases. The
highest incidence of sclerotinia disease was found in the potato/canola/alfalfa/alfalfa rotation.

Soil analysis indicated little change as a result of any of the
rotations.

The rotation study, funded by the Manitoba Horticultural Productivity Enhancement Centre and Agriculture and Agri-Food Canada’s Matching Investment Initiative, will be continuing until 2010.

“We are starting to look at weed levels now,” Mohr says. “We think crop rotation may be better able to control weeds.”