Recent years have seen increased attention on the health of the soil used in potato production, and attempts to bring potatoes into longer rotations with other crops, writes Ralph Pearce, CG Production Editor in Country Guide.
He says that in Canada’s Maritime provinces, seed companies are promoting soybeans or corn as rotational options, and McCain has developed one- and two-year multi-species cover crop blends to help boost organic matter and limit erosion.
Sheldon Hann, a biologist with Agriculture and Agri-Food Canada (AAFC) in Fredericton, says there is a direct correlation between organic matter and crop production — the higher the level, the higher the yield.
The challenge across much of Eastern Canada is that some rotational crops such as soybeans and dry beans don’t add much residue to the soil. Aggressive tillage on sandier, porous soils with potato production in the Maritimes also makes it difficult to maintain organic matter.
That’s prompted an interest in “nurse” crops planted along with potatoes. In 2015, Bernie Zebarth (now retired), one of Hann’s colleagues in Fredericton, began a multi-faceted project to find opportunities to lengthen rotations, improve soil health, improve yields and enhance biodiversity.
Hann found that the field pea nurse crop didn’t need a spray treatment since the mechanical hilling killed the crop. Winter rye, a denser, more aggressive species, required desiccant. Hann says if the winter rye remained it would act as a weed and compete with potatoes for nutrients and water.
The project ran for three years with one-year and three-year trials.
Hann wants to expand the research and grow potatoes to a two- or three-year rotation with a grain or a forage-and-grain option to determine whether there’s an increase in biodiversity, and what happens beyond boosting yields.
“In Bernie’s study, one of his main findings was that a relatively small increase in tuber yield would be sufficient to justify the extra costs associated with growing the nurse crops,” Hann says.
Photo: Researchers are assessing the benefits of crops seeded into potato hills, similar to this nurse crop in carrots. Photo credit: Ralph Pearce