Q: Are there benefits to a cover crop for forage establishment?
A. There are many benefits to planting a cover crop (sometimes referred to as a companion or nurse crop) for forage establishment. Cover crops commonly planted alongside perennial forages include oats, barley and wheat.
Before a forage stand becomes well established, bare soil can be left exposed. A cover crop can provide ground cover more quickly than a newly planted forage, reducing evaporative water loss, soil erosion and weed competition. However, cover crops compete for water and nutrients and can shade the forage crop from sunlight. This takes resources away from the forage crop and often results in slower establishment. Forage stands established under a cover crop are typically less productive than those planted without a cover crop in the year of planting, and sometimes several years after. The biomass produced by the cover crop offsets this difference, but forage productivity is reduced.
A cover crop can be a practical solution in high-risk scenarios in terms of soil erosion, soil crusting, weed pressure, or when it is imperative that silage or greenfeed be harvested in the year of planting. When planting a cover crop, choose a less competitive species and seed at less than half of a normal rate. Be mindful of nutrient levels as well; high nitrogen rates encourage vegetative growth in the cover crop, which can lead to lodging and excessive shading of the forage crop. Harvesting the cover crop as silage or greenfeed is advisable because competition is alleviated early in the season. Allowing the cover crop to mature to be harvested as grain is not recommended.
Choosing to plant a cover crop can be highly beneficial, but there are also potential drawbacks. Assess your individual risks and priorities to determine if a cover crop is the right fit for your operation.
Stacie Yaremko, BSc, CCA, is a manager of agronomic services with Nutrien Ag Solutions in northern Alberta.