Pushing marginal land into grain production may add up to short-term gains when grain prices crest. But it comes with risks, too. “I would have some grave concerns about the notion of bringing marginal land back into annual grain production,” says Dr. Reynald Lemke, research scientist with Agriculture and Agri-Food Canada. Lemke examines how farming systems affect soil quality and greenhouse gas emissions. “My presumption is that it is marginal and now maintained under a grass cover or some sort of permanent cover for a reason.” So before breaking that land and seeding canola or wheat, it’s worth considering how well those risks can be managed.
Why is it marginal?
Farmers may eye land under forage or grass cover as potential grain acres. But pulling this land into annual production will degrade soil somewhat, even if farmers do the best job possible. “I think it’s just the nature of the beast that you are going to pay some price in terms of soil carbon balance. And, of course, with that some fertility and so forth.” “Marginal can be considered marginal for many reasons. The reason that it’s classed as that will have a large impact on whether or not it’s all feasible to bring it into annual grain production,” says Lemke. Sandy soils are more likely to leach nutrients such as soil organic nitrogen. Sandy soils and sloping land are also “particularly fragile in terms of soil structure and erosion risks and so on,” Lemke adds. Steep land and sandy soils are drought-prone. Native prairie in southwestern Saskatchewan also has moisture limitations. Most farmers have seen adequate, or more than adequate, rainfall in the last few years. But it’s impossible to know how long this rain cycle is going to last. “And if we move into more marginal areas, and then we run into a drier spell, that could really cause some issues here,” says Lemke. Other marginal land might have specific problems such as very acidic soil, or shallow soil, Lemke adds. Sometimes farmers can do precise things to offset issues such as acidity. Such problems have to be addressed on a case-by-case basis, he says.
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Three ways to beef up management
Lemke says recommendations for managing marginal land are often the same for other fields, but the risk is much higher. Farmers will need to pay attention to all management aspects to optimize production and maintain biomass, he says. The three main things to do are minimize tillage, exclude fallow and maintain the best cover possible. Zero tillage is best, and summer fallow is a no-go on marginal land. “So if you’re in an area where there’s moisture limitations, even chem fallow still increases your risk beyond say, continuous crop.” Marginal land is generally more vulnerable to water or wind erosion. A permanent cover, such as grass or forage, does the best job of holding soil in place, building soil organic carbon and maintaining structure. But farmers can help maintain cover by extending the rotation or otherwise tweaking the rotation. “You might consider pulling it into canola production, for example, then back into forage for a few years,” says Lemke. He adds this may not work in all situations, especially in areas short on moisture. Farmers also need to manage fertility more carefully on marginal land than other acres, he says. Once the management plan is in place, it’s worth penciling out the economics again. “If you need to take these extra measures to try and do the best job you can of protecting the soil, does that balance out or not?” †