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Cover crops gain popularity

Ontario cash cropper Blake Vince can remember the moment cover crops really piqued his interest.

Vince was in the U.S. for a farm meeting a few years back and started comparing notes with Ohio farmer David Brandt. Brandt was trying to persuade Vince there was a better way to farm, one that reduced tillage and depended more on cover crops.

As a member of a family of farmers noted in their area for being no-till pioneers, Vince was interested, noting that the initial theoretical foundation of no-till always intended to incorporate the cover crop practice. But it was the bottom line numbers for similar yields that really got his attention.

“He was using a hundred pounds of N on his fields, and for about equal yields, I was using 180 pounds,” Vince says. “At that point I said to myself, ‘Who’s making the money here?’ The answer? ‘Not me.’”

"There’s a fairly large number of growers that appear to be interested in improving their soil life and overall soil health."

Benefits of cover crops

Returning home, Vince looked around the family’s 1,300-acre operation near Merlin, Ont., where they grow corn, soybeans and wheat, and realized any strategy that could help him reduce fertilizer would be a winner. Not only would it help his bottom line, it would help offset increasing environmental pressure based on issues like surface water quality.

Vince adds diversity to his rotation these days with his cover crop mix, which contains 17 plant species, and he typically sows it in the first or second week of August, after winter wheat harvest.

The mix not only helps hold down the topsoil and prevent erosion and runoff, it also fosters the soil biota – the living things like beneficial bacteria and mycorrhizal fungi that form mutually beneficial relationships with crop roots and make them more efficient users of fertility – by keeping living plant tissue growing in his fields at all times.

“I’m not interested in the maximum possible yield,” Vince explains. “I’m interested in the most economically and environmentally efficient yield.”

Vince says he sees the numbers every season, and he’s satisfied the strategy is working. Yield is holding its own, fertilizer use is down and the bottom line looks healthier. Even more crucially, overall soil health has improved.

Vince is just one of a growing cohort of innovative growers adopting the technique, says Dr. Laura Van Eerd, a soil scientist based at the University of Guelph’s Ridgetown campus.

Trend or fad? Cover crops go mainstream

“I would say we’re past the early adopter phase now, and it’s begun to creep into the mainstream,” Van Eerd says. “About a year ago I was asked if cover crops were a fad or a trend, and I didn’t really have a good answer. Now, with another year of experience, I would say they’re definitely more trend than fad.”

The practice has been a long-standing one for vegetable growers in the province. Those crops typically are tillage-intensive, especially during harvest operation for root crops, but in recent years cash-crop growers like Vince have taken the practice into fresh fields.

Cover crop techniques

“Right now, farmers are trying a lot of different things and figuring out the agronomics of cover crops,” Van Eerd says.

The issues under examination include the timing of seeding, whether a crop can be under-sown with another crop, and what cover crops make sense. One technique garnering a lot of interest is sowing into corn and soy fields well before harvest. This technique requires careful timing and there are a few different practices under examination.

Some farmers are using a single species, including legume crops and specialty cover crops like tillage radishes. Others, like Vince, are seeking greater diversity by using multi-species mixes. Those can be more expensive, but they’re also seen to deliver better bang for both the monetary cost and the investment in time and management.

“What the preferred cover crop species is depends on the goal of the grower. Cover crops were first in the marketplace, so to speak, in Ontario in the late 1980s, and then the goal was primarily erosion control,” Van Eerd says. “Now the goals are a lot more varied.” 

Van Eerd recently led a project that adapted a cover crop decision-making tool for Ontario growers. It acknowledges the many different options and goals, and helps growers refine their thinking and selection.

“It has farmers pick their goals and benefits, and screens the various cover crops based on this,” Van Eerd says. “For example, they might be looking for a weed fighter, and this ranks the cover crops from one to four as weed fighters, and anything below a two will be removed from the list.”

Van Eerd began to research cover crops in 2004, when they were largely seen as an oddity. “In 2007-08 we began to look at cover crops in a long-term rotation study on the Ridgetown campus, and we’re starting to now see some of the long term effects in terms of better overall soil health.”

These sorts of long-term studies will help researchers and the farmers who apply the findings better understand the true value of cover crops as part of a production system.

From an AgriSuccess article by Gord Gilmour.