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Cover crops not the key to successful forage establishment

An Alberta applied research group does not recommend using cover crops in forage stand establishment, saying that the cover crops can be detrimental to the health of the new forage crop in many regions of the Prairies.

The Battle River Research Group (BRRG) based in Forestburg has shown through a demonstration project that the use of cover crops in forage production actually does more harm than good.

"In our demonstration plots, forage plants established with a cover crop tended to be spindly and had few leaves," says Jenifer Heyden, a forage and livestock agronomist with the BRRG. "Cover crops compete with forage stands for water, light, nutrients and space making the forage less productive and less healthy."

The demonstration project received funding from the Greenhouse Gas Mitigation Program for Canadian Agriculture (GHGMP). The federal program is designed to promote awareness of agricultural practices that reduce atmospheric levels of greenhouse gas or increase carbon storage in soils. The Canadian Cattlemen's Association administers the delivery of the beef sector component of the program.

Modelled on a similar Saskatchewan project, the Battle River demonstration involved three sites - one in the County of Beaver and two in the County of Paintearth. Barley, oats, triticale and annual ryegrass were used as cover crops seeded along with meadow brome, smooth brome, tap rooted alfalfa and creeping rooted alfalfa as forage crops. Heyden says each site was monitored throughout the summer of 2003. The results showed that cover crops were not the best management practice for forage establishment.

"Properly established forage crops which lead to thick, healthy stands, are a key component to carbon sequestration in the soil," she says. "Forage plants are able to capture carbon dioxide from the atmosphere and store a portion of that as carbon in plant tissue and in the soil."

Maintaining a perennial forage stand increases the amount of stored carbon in the soil, which can improve soil fertility and productivity and protect the soil from wind erosion. As well, perennial forage stands, especially those containing a legume, require fewer annual fossil fuel inputs, such as fertilizer, fuel and machinery wear and tear, compared to annual crops she adds.

The project did identify one short term disadvantage to not using cover crops. Plots with no cover crop were more susceptible to weed infestations. However, Heyden says mowing and forage crop competition eventually suppress weed production. "Over time, any weed seeds in the soil will decompose," she says.

A healthy forage crop benefits the livestock industry by providing a sustainable forage resource, says Heyden. She adds that establishing a healthy stand initially is important in maintaining yield and forage quality over the long term. Also, improvements in production efficiencies associated with highly productive forage stands reduce the amount of greenhouse gas emissions per pound of beef produced.

"Producers should notice the added benefits of having a healthy forage crop," says Heyden. "Good management practices improve production efficiency and that is good news for people looking to run efficient operations."

The GHGMP supports a broad range of projects across Canada. For more information on this project and other beef sector activities, visit the CCA's Web site: www.cattle.ca.

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