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Nitrogen fixing pulse crops are a win-win for growers

There’s a compelling economic and agronomic case to be made for pulses, not just soybeans

If you ask Lee Moats why he grows pulse crops on his farm, he doesn’t have to scramble very hard for the answer to that question. “It’s about money,” the farmer and vice-chair of the Saskatchewan Pulse Growers Association told Country Guide during a recent discussion.

On his farm at Riceton, Sask., Moats says they’ve been growing pulse crops for the past 24 years, and the numbers place the crop at the top of the rotation.

“I would bet that lentils provide the highest net income per acre over that time period,” Moats says.

Lee Moats

“If you include pulses in your rotation,” says Saskatchewan lentil grower Lee Moats, “your carbon footprint goes way down.”
photo: File

Other growers in the province have voted with their equipment, and these days every year sees something close to 1.7 million acres go into the ground in Saskatchewan.

One of the big reasons those numbers make sense is because of a notable agronomic feature of the crops — their ability to fix their own nitrogen. They fix atmospheric nitrogen and convert it to nitrate nitrogen that’s immediately usable by the crop.

“That’s really important because it means that our nitrogen input into pulse crops is zero for all intents and purposes,” Moats says. “It’s supplying its own, and that of course is a cost reduction.”

Purely economic considerations aside, more and more consumers and companies are also paying closer attention to the environmental bottom line, another way the crops stack up nicely.

“With sustainability questions on a number of fronts, if you include pulse crops in your rotation, your carbon footprint goes way down,” Moats says.

In a lot of ways, growing nitrogen is a bit of back to the future for farmers. Before Fritz Haber and Carl Bosch invented an industrial process for fixing nitrogen from the atmosphere so it could be delivered to farm fields, it was essential in any farmer’s rotation to include a legume crop. Most were forage crops like clover or alfalfa, which fed livestock like draft horses.

These days there are a lot fewer horses on farms, and subsequently a lot fewer forage acres, leaving a nice niche for pulse crops to fill. Because while there’s a lot of control that comes with carefully feeding a crop with chemical nitrogen, it costs money and it ignores some of the underlying relationships that exist in fields. For example, legumes also encourage nitrogen-fixing bacteria, further amplifying the effect.

They also leave a high-residue nitrogen that helps keep some bills low, while also helping to pay others, says Neil Whatley, Alberta Agriculture pulse crop specialist.

“There’s residual nitrogen left over for the next couple of crops,” Whatley says. “Pulse crops have a higher nitrogen-to-carbon ratio, so it provides a little bit of soil nitrogen to those other crops through the next growing season. So a wheat crop, after a pulse, usually gets higher protein because the wheat takes it up later in the growing season, and that translates into protein.”

It also adds diversity to the rotation, giving farmers an alternative to a two-crop rotation of wheat and canola. This does two things. First it provides a disease break with a longer stretch of time between a cereal and canola crop. Since pulses are susceptible to different diseases, there’s then more time for the inoculum of established cereal crop diseases like rust or fusarium to break down in the soil, and a similar pattern occurs for blackleg in canola.

The second is the ability to rotate herbicide products. “You can use different herbicides, things like Odyssey, so we’re talking Group 2 and then something like Poast, which is Group 1,” Whatley says. “So you’re using different modes of action for another whole plant family. You actually reduce the chances of weeds developing herbicide resistance.”

Another pulse crop specialist, Manitoba’s Dennis Lange, agrees the addition of herbicide groups is a good thing, but adds this is one of those areas where there can be a bit of a saw-off for producers. Weed control with some of the pulse crops, especially ones like edible beans, can be a serious challenge, he says, and it may require a higher level of management, such as incorporating a pre-emergent application of Edge or Treflan.

“When it comes time for growers to spray, the conditions may be a little cooler than ideal and that makes weed control more challenging,” Lange says. “Not only can they choke out yield but they can also cause quality losses. If you have too many weeds in the field, come harvest time, if those weeds are still green you get this staining from the moisture of the weeds.”

Another trade-off is field preparation and selection. Many of these crops, in particular field peas, ripen close to the ground, making for some big harvest challenges that can only be managed at the start of the season by rolling fields. Rolling serves to flatten the ground and punch stones back under the surface, keeping both dirt and stones out of the combine. A flex header will do a better job of harvest, but it’s no guarantee of safety.

There’s also the issue of what the crops themselves require from a field. In most cases, the answer to that question is good drainage, says Saskatchewan provincial pulse crops specialist Dale Risula.

“They don’t like wet feet, so we’ve seen problems develop with root rot organisms that have shown up in the pulses and can be quite devastating to a plant which is strongly dependent on a good, healthy root system,” Risula says. “You probably want to have a lighter-textured soil, fairly flat but draining well and not compacted. That’s generally what we’re seeing right now with the pulses.”

All that adds up to some pockets of production for the various crops throughout the Prairies, depending on local soils and production climate, grower base and other variables.

With 1.7 million acres, primarily of peas and lentils, Saskatchewan is definitely the big player in the game. Alberta and Manitoba are also significant producers of the crops, but smaller.

In Alberta there’s a wide variety of various pulse crops grown, says Whatley. About 70,000 acres of edible beans were grown, for example, mainly in and around Lethbridge and Bow Island, where there’s irrigation.

“These are fairly minor crops,” Whatley says.

The main Alberta pulse crop is field peas, with about one million acres planted, throughout the province. Red lentils are another cropping option, with between 100,000 and 140,000 acres.

“It’s steadily growing in the dry to moderately dry areas in the southeastern and east-central parts of the province,” Whatley says.

In Manitoba, it’s a tale of two distinct regions, says Lange.

“If you were to draw a line from Altona then to Winkler, up to Carman and over to Portage la Prairie, that’s where most of the edible beans are grown,” says Lange. “If you were to go to the western part of the province, most of the field peas are grown there.”

This article was originally published as, “Winning pulses” in the Feb. 3, 2015 issue of Country Guide

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