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Grow your own nitrogen

As the cost-price squeeze reasserts itself, those old ideas about producing your own nutrients might become new again —- which means the organic industry might have a thing or two to teach us

Near Oxbow, Sask., organic producer Ian Cushon spends a lot of time and energy trying to produce the key building block for plant life — his own nitrogen — because unlike most growers, Cushon can’t just spread some fertilizer and be done with it. If he wants to play the organic game and capture those market premiums, he must abide by the rules that say chemical fertilizers aren’t allowed.

To Cushon, that means adopting some of the strategies that our great-grandparents would have been very familiar with, things like growing and then plowing down “green manure” crops, or planting nitrogen-fixing crops either along with or after more traditional grain crops.

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Broad bean green seeds lat. Visia faba. Fava bean

These are strategies that he has been able to fit to his own farm. But does he think they might fit the larger grain industry as a whole? We asked him.

“It’s definitely something we have to work at,” Cushon responds. “I think these strategies make sense for us, and some of them might make sense on non-organic farms, but those farmers are going to have to look pretty hard at it and make that call themselves. Some of them, I think, would be really difficult to justify without organic premiums.”

Despite that hard reality, non-organic growers are starting to kick the tires of some organic techniques, according to one researcher at the University of Manitoba. Martin Entz teaches natural systems agriculture and is a well-regarded researcher into natural techniques to optimize crop production. He’s been seeing scores of farmers at recent field days, including some fresh faces that haven’t been part of his traditional audience.

“A number of these farmers were conventional farmers… people who I’d never seen before,” Entz says. He’s excited that the message seems to be creeping outside of its traditional audience, and he confirms the most likely reason for this shift is their increasing anxiety about an extended run of lower grain prices that will bring the concept of cost-containment once again to the forefront of farm thinking.

“It’s not really clear what the market and grain prices are going to do over the long term,” Entz says. “That may be why we see more conventional farmers coming.”

The first and most obvious way for growers to begin producing some of their own nitrogen is to incorporate a grain legume, such as peas, lentils or soybeans. This is a very important way to have at least one crop grow some of its own nitrogen and reduce costs, Entz says, stressing it’s also a relatively simple adjustment for a farm rather than a wholesale renovation of production practices.

“This is a good opportunity, and one that fits in with most farms,” Entz says. “It’s certainly one we see a lot of farmers interested in exploring during times of high nitrogen prices.”

A more complex system may involve undersowing nitrogen-fixing crops or planting cover crops in the fall. These techniques are still very much in their modern infancy in Western Canada, though they are much more common in warmer and wetter growing areas elsewhere.

Entz says the real challenge for anyone wanting to try these strategies is to find a window where the cover crops will fit. For a fall crop, for example, you’ll need to have the preceding crop come off in good time so you have enough season to get sufficient growth to make it worth your while. You’ll also have to have enough available moisture to ensure crop establishment. If it works, though, it can be worth it.

“You can grow a significant amount of nitrogen, if you have enough time to get it planted and enough available moisture,” Entz says.

How much nitrogen? That depends on what you’re growing and where. Entz says a study by the University of Manitoba about 15 years ago found that locations throughout the Prairies returned between 10 and 60 pounds of nitrogen from cover crops, meaning there is some potential on the upper range to make this practice pay dividends.

“To make it economically interesting, I think you’d need to hit at least around that 30-pound mark,” Entz says.

Ian Cushon says he’s had success with both techniques on their farm, and he confirms selecting the appropriate crop to fill this role is an ongoing challenge, one he continues to refine. His latest test subject is fababeans.

“Last year I just planted a small plot in the garden in mid-August to see how they would do over that six-week period, and they performed quite well I thought,” Cushon says. “I may try them on a larger scale this fall, but I’m still not entirely convinced — they need a fair bit of water and I think they might be better suited to the northern Grain Belt.”

Cushon says there are a number of potential crops that growers can try, however, and within that list there may be a winner for an individual farm. For example, he says he has either personally used or knows growers who have used forage peas and Indian Head lentils, and he is also familiar with growers and researchers who have experimented with various vetches, a family of small flowering legumes that is typically undersown. None of these options have proven to be a “one-size-fits-all solution,” something Cushon said highlights the need for more basic agronomic research in the area, such as that being undertaken by Entz and his team.

“They’ve done a lot of great work, and I think we need to keep looking at this pretty closely,” Cushon says.

It may be a mistake to look at these techniques entirely in the light of nitrogen production, however, since there’s also a lot of evidence that keeping plant material growing on agricultural lands throughout the growing season is good for the soil. It keeps organisms like fungi and mycorhhyza fed, happy and active, in return for which they help improve the efficiency of the crop’s nitrogen uptake.

“The soils are able to cycle nutrients more efficiently, and they let the plants use that nitrogen more efficiently. There’s definitely a benefit from having healthier soil overall,” Entz says.

Entz says the technique has become known as carbon fertilization, because it provides the sustenance to the soil microbes in the form of carbon, and there is definitely a crop response that’s observable and measurable. Ian Cushon says he’s seen it himself on his farm, and it’s one of the reasons he spends his time and energy on this challenge.

“It’s definitely real, but I suppose the challenge is quantifying it and determining what the economic advantage is, especially for non-organic farmers who want to try some of these things,” Cushon says.

That’s important because the system might pay dividends, but it’s not going to be free to implement. Cushon ballparks sowing a fall cover crop at around $50 an acre, when the cost of the seed and the fuel, time, and wear and tear on equipment are figured in.

“I don’t know if you could make it pay if you were strictly looking at the amount of nitrogen you could fix in the soil,” Cushon says, noting that in his mind it’s the combination of the nitrogen and the soil health benefits that put the system over the top.

Not just N

More conventional farmers are starting to show up at Martin Entz’s field days on sustainable nutrient management.

More conventional farmers are starting to show up at Martin Entz’s field days on sustainable nutrient management.
photo: Shannon VanRaes

Animal manure should be treated more like a valuable resource and less like a liability to be quickly and quietly disposed of, says Martin Entz, University of Manitoba researcher.

In particular, Entz is concerned about phosphorus, which is contained in particularly high levels in hog manure. For the past few years this nutrient-rich manure has been applied to maximum environmentally acceptable levels, usually without regard for what the crop actually needs.

“We talk an awful lot about N, and I think this gets missed,” Entz says. “Phosphorus we haven’t talked nearly as much about, and when we do, it’s in terms of the environment, not how we can actually get more use out of it.”

With more and better manure management equipment, and with manure composting seemingly really coming into its own, Entz says the time might be right to reconsider the applications, noting that for farmers with nearby livestock operations, this might represent some low-hanging fruit to be plucked when trying to optimize plant nutrient efficiency.

Says Entz: “If we do this, we could potentially reduce phosphorus fertilizer costs, and we won’t see soils loaded with the maximum amount of phosphorus they can take.”

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