The soil has its own perspective, says soil scientist Mario Tenuta, which explains why in Western Canada, where intensive farming has “only” been going on for 100 years, our soils are actually still young.
“Our soils are not mature, compared to places like Europe or Africa,” Tenuta says.
Over the last 50 years of farming, however, our soils have changed fairly dramatically — in part because farmers have moved away from perennial crops in their rotations. That’s a bigger change than we might at first think.
“Our soils on the Prairies are perennial soils to begin with; they evolved with grasses that are perennial,” Tenuta says. “We’ve turned it into annual rotations and have lost a lot of organic matter from that.”
So these days, is it possible to farm sustainably without forages in the rotation?
Tenuta, the Canada research chair in applied soil ecology and professor in the Department of Soil Science at the University of Manitoba, has done a lot of research into the question.
He believes farmers shouldn’t think purely in terms of environmental sustainability when it comes to cropping decisions. Prairie crop production of oils and cereals is largely for export, he says, which means sustainability needs to be considered in light of maintaining a healthy export market.
“We’re exporting nutrients, so we have to care about quality and be competitive in the global market,” Tenuta says. “To be sustainable, we have to be cost competitive. This is extremely key, because we’re in a global situation on the Prairies in terms of competition. We want to be able to practise farming that will allow us to be competitive on a global market and to export a high volume of high-quality commodities.”
So what does that mean in terms of cropping decisions? For Tenuta, it comes down to diversity.
“That’s an advantage we have: canola, wheat, soybean, flax, barley, edible beans; we are very fortunate that we’re not doing corn/soybean rotations, or relying on just one commodity,” Tenuta says.
“Our growers can switch over and plant more peas in western Manitoba, or put more soybeans in, or switch between wheat and canola.”
Economic sustainability, in a Western Canada context, depends on environmental sustainability. In other words, diversity of crop inputs is crucial when it comes to maintaining the quality of the soil, and for managing where and how each crop is produced.
Farming with forages
Forages have long been the “poster crop” for soil health — with good reason. Their contribution to soil health and soil fertility is stunning. There are improvements in soil structure, improved drainage and water holding capacity, higher rates of carbon allocation into the soil, reduction in erosion losses, deeper rooting systems that reduce salinization, and improved nitrogen fixation (with alfalfa and legumes), plus a host of other ecological goods and services.
For Jeff Schoenau, professor of soil science at the University of Saskatchewan, forages are key to maintaining soil organic matter and soil quality, and they also offer permanent, protective cover for problem soils.
Schoenau’s research team has looked at the effect of putting marginal, annually cropped land into permanent cover. They’ve also looked at the effects of adding short-term forages to the rotation.
“Forage mixes that contain a legume, like alfalfa or clover, can fix nitrogen from the air, and that’s an external input of nitrogen into the system that benefits the forage and the soil, and that replaces fertilizer,” he says. “In work I’ve been involved with, we’ve seen some significant fertilizer nitrogen replacement values — even for a short time, such as two years of alfalfa or two years of red clover.”
Not surprisingly, Schoenau and Tenuta both recommend farming with forages. But they warn producers not to expect a silver bullet.
“We recommend growing perennial forages, but if everybody followed our recommendation we’d have more forages than we could deal with — there would be no value to it. So this is the issue,” says Tenuta.
Marketing is the age-old problem with forages. “There is a tendency to move to straight grain or straight livestock these days, while I think a mixed farm operation with annual crops and livestock makes it the easiest to incorporate those forages into rotation with annual crops. For grain farmers, time and equipment constraints can make it challenging to harvest that forage and put up the bales, and then you’ve got to market it as well,” says Schoenau.
Farming without forages?
Can farmers farm sustainably without forages in the rotation? Tenuta’s response is that it’s much easier with forages in the rotation — as long as there is a market.
If farmers stick only with annual crops, their task will be much tougher in the long run, because the soil will be “pushed” on an annual basis, and the soil will be bare in the spring and fall.
Tenuta says there are some options for growers who are looking to improve sustainability practices, especially if they find ways to farm in the “shoulder” seasons in the spring and fall. Key options includes cover cropping by either relay cropping or underseeding crops.
“I’m not saying you can’t be sustainable without perennials, because somebody somewhere will prove us wrong, but it will be easier if you have perennials in the system, particularly because the quality of the soil will be better when you produce annuals,” Tenuta says.
“In prairie Canada, our production systems have to change. Our systems don’t look like they did 20 years ago. For growers, this means they’ll need to be learning constantly and be open to change — new crops, new soil management practices, new ways of producing food,” says Tenuta.
And for the research community, Tenuta believes there should be an infusion of investment into winter wheat as well as perennial wheat and grains.
“It’s a very, very minor investment to date,” Tenuta says. “If we put our brains to it, we could make some decent strides.”