Dr. Judith Nyiraneza, a Research Scientist with Agriculture and Agri-Food Canada (AAFC), recently completed a two-year study testing the performance of cover crops. The crops were planted on the Oyster Cove Farms of Hamilton, P.E.I., following the potato harvest, and have yielded positive results.
In P.E.I., there is a high risk of soil erosion. The humid climate, sandy soil, and aggressive production all play a part in valuable topsoil being lost after a harvest. This results in lower future yields and higher costs for producers trying to remedy this issue. There is also the risk of groundwater pollution as agricultural chemicals from the soil are swept into local water sources.
“We have to do anything we can to minimize the time soil is left bare without anything growing,” said Nyiraneza.
Cover crops can mitigate some of these issues. These crops are plants that are planted to cover the soil rather than for the purpose of being harvested. They increase organic matter and nitrogen in the soil, protect it from erosion, promote beneficial insects, deter weed growth, bring up deep-rooted minerals, and increase the soil’s moisture-holding capacity.
Nyiraneza’s two-year study tested the effect of winter rye, winter wheat, and spring barley as cover crops and the effect on the soil. Throughout the study, the researchers regularly measured the soil movement caused by raindrops, the soil’s vulnerability to erosion, and the amount of carbon and nitrogen, as well as the amount of nitrates.
All three crops used as cover crops showed positive results. They decreased the risk of soil erosion and reduced the amount of carbon and nitrogen that would be lost in the soil compared with no winter cover control. On top of this, winter rye and winter wheat recovered quickly in the early spring, providing additional protection from erosion as a result of the snow melting.
With the completion of the two-year study, Nyiraneza and her team are continuing to research the potential of cover crops. Future experiments may include seeding winter cover crops ahead of the potato harvest as opposed to waiting until after.
“After harvest, there is a short window,” said Nyiraneza. “However, there are growers who plant cover crops just a few days ahead of the potato digging, so that while they are digging, they cover the seed with soil and then it does germinate. Today we are testing multiple species,” she said. “When you seed ahead of potatoes, you have more potential. You can use oats, radish, oats mixed with radish, or mustard mixed with radish. There are more possibilities when you seed a little bit earlier – late August or early September.”