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Pulses and other special crops in no-till, low input systems

Following nature's lead is best.


November 27, 2007
By Ralph Pearce


Topics

When it comes to growing better crops in the semi-arid regions of the prairie
provinces, the best advice from a pair of researchers is to look at what nature
is doing and get back to the basics of crop rotation.

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"The way I look at cropping systems in the bigger picture for
those dry regions is that we have to find a way to get some diversity into
that system," says Perry Miller.

Using pulses in wheat rotations is common for Saskatchewan and Alberta farmers.
But the perception that various climate and soil types are challenging growers
is somewhat unwarranted, says Dr. Perry Miller, associate professor of cropping
systems in the Land Resources and Environmental Sciences department at Montana
State University in Bozeman. Miller, who worked for a time in Swift Current,
Saskatchewan, is an advocate of using pulse crops and other alternatives in
no-till, low input and organic cropping systems.

The value of pulses has come to the forefront recently because of increased
energy and input costs. Fuel costs are US$3.00 per gallon and nitrogen has become
expensive. Miller recognizes the economics of pulse crops in the Northern Plains,
"But when I talk to farmers, it's really the systems benefit that's sustaining
their interest in pulse crops," he says.

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Miller cites additional farmer benefits, such as easier grassy weed control,
higher-than-expected re-crop wheat yields and improved wheat quality as tangible
rotational benefits. "For this reason, I think the Montana-Dakota region
is poised to accept pulse as a significant component of crop rotations unless
there are significant economic roadblocks that emerge."

Miller's three primary choices for rotations are peas, lentils and chickpeas
for their ability to grow in semi-arid regions. "The way I look at cropping
systems in the bigger picture for those dry regions is that we have to find
a way to get some diversity into that system, otherwise pests are going to run
us out of town," says Miller. He adds that such a scenario will develop
with no-till systems, particularly with a mono- culture of wheat. "The
pulses I look at don't need as much water as other crops and they do rotate
nitrogen to those cereals. That's an important difference in addition to different
herbicide options and some of the grassy weed populations that build up during
wheat production years."

Miller has tried using fababeans, lupins, dry beans and soybeans as rotational
crops within a new system. But each, especially fababeans, has a greater need
for moisture than peas, lentils and chickpeas. With soybeans, he has trouble
getting the plant to set pods, let alone establish a solid crop, again, due
to a lack of moisture.

Determine the driver, first
One of the first tasks in reworking rotations and implementing no-till strategies,
notes Miller, is to determine the goal behind such a switch. Is it a means of
attaining higher yields in subsequent crops, to control weeds and improve soil
health, or to reduce costs on inputs? Or is it a combination of all three?

If growers are going to adopt no-till and higher intensity rotations, continues
Miller, they need to adjust their thinking beyond the conventional wheat-fallow
system. "It's really critical that we grow some biomass, some living plant
material on that soil, every year," he says, adding his research is now
looking at green manures, using a pea or lentil crop that is terminated chemically.

A recent study by Dr. Rob Zentner of Agriculture and Agri-Food Canada's Swift
Current Research Station found conclusive benefits to this method. Miller says
that green manure in a cropping system in that region can actually pay if you
manage it right and leave it in long enough. He says it pays better than having
a tilled fallow or a chemical fallow field, although the perception is that
green manure actually cost growers.

Many opting out of wheat
Convincing growers to adopt other crops may not be a hard sell in the current
economy, but the procedure behind such a move can be a challenge. Miller concedes
a great number of farmers are adopting diversified rotations but more because
of wheat's falling price.

"It's not very hard to convince them they need to put those crops in their
systems when the alternatives are actually paying more than their wheat,"
says Miller. But he is trying to convince growers of the benefit of maintaining
wheat while diversifying their operation with pulses and other alternatives
suited to their particular conditions. "Wheat is absolutely a critical
backbone to rotations, just because of the durable residue it leaves behind.
It protects the soil, it provides carbon and I couldn't seriously envision anybody
trying to get in a rotation where wheat isn't a predominant crop, but I know
some farmers are talking about that and it makes me nervous."

Miller acknowledges the need for more research into developing greater diversity.
He has worked with sunflower and safflower, or trying the winter versus spring
cropping angles, but all have their drawbacks. "The bottom line is that
even in my research plots, we're a long way from having achieved the diversity
I would like to see in semi-arid cropping systems for the Northern Plains,"
says Miller.

Return to yesterday
Dr. Dwayne Beck, research manager of the Dakota Lakes Research Farm with South
Dakota State University in Pierre, takes the theory of using pulses down to
an even simpler level. Beck is considered a leading authority on crop diversification.
He puts his research into practice on the 1200 acre Dakota Lakes farm, and must
derive a significant proportion of his research dollars based on the success
of his production methods. His motivation is tangible: the better he produces,
the more research he can undertake.

From more than 20 years of field studies, Beck has developed some guiding principles
for growers wanting to move into using pulses and rotations with no-till systems.
The first is to simplify and go back to the basics of prairie agriculture. For
too many years, he says, agriculture has attempted to fit cropping or rotation
systems that growers want into the conditions present on a farm. But Beck insists
nature has to be a consultant in the process: growers need to ask what the ecosystem
at a particular location will allow them to do, then work within those parameters.

Beck's approach is more of a co-operative effort than the conquering mind-set
of the past few decades. "If you have a weed or a disease or an insect
problem, you've done something to create that opportunity," explains Beck.
"And now you have two choices: go buy something to kill that, and keep
providing the opportunity and hope it doesn't develop resistance, or go back
and look at your system and understand how that opportunity developed."

Old ways can be good ways
Beck maintains that older methods of weed control can still apply today. Using
alfalfa, tame oats or millet to control wild oats is one example. "What
we're doing is using rotations that never provide the weeds an opportunity to
build populations," he says. "One of the big things is not to be predictable
in terms of either sequence or interval and how we stack crops in there. In
other words, if we plant a crop too often, or always after a one year break,
or always following the same preceding crop, weeds figure that out."

Instead, growers need to look at what has happened on the prairie. Regions
in southern Alberta and Saskatchewan have done without tillage for thousands
of years, notes Beck, who decided to focus his work on the mechanics of the
prairie in those regions, then try to mimic those processes. "We determined
that with no-till and the proper use of crop rotations, we can't really mimic
the prairie but we can come much closer than before," says Beck. "If
you look at the prairie, it has warm and cool season grasses, it has warm and
cool season broadleaves. Good crop rotations need all of these, as well. Having
rotations of only wheat-peas or wheat-pea-wheat-canola will eventually have
problems because of a lack of diversity."

Where the pulse enters the plot
Understanding the need to shift that focus is just part of the process. Beck
echoes some of Miller's comments in rotating pulses with wheat or growing something
in place of fallow. "The goal in replacing the fallow was not to make money
with the peas or the flax or the canola, we just needed to lose less money than
it cost us to summer fallow," says Beck. "As soon as you can get that
through to the grower, that's the point where they turn it around."

Another key to his approach is understanding the difference between the nitrogen
a pulse crop supposedly provides and its low carbon production. Harvesting a
pulse crop for grain removes most of the nitrogen it produced. Leaving the pulse
crop in the field (green fallow) leaves the nitrogen in the soil. Additionally,
the nitrogen credit given the year after production of a pulse crop for grain
comes because a broadleaf crop produces and leaves less carbon in the field
than crops like wheat. That means less organic matter will be produced the year
following peas as compared to the year following wheat. Growing low carbon crops
too often will mine organic matter even under no-till.

"We still need to use fertilizers (in non-legume crops), since nothing
ever left the prairie (before the land was broken for agriculture). We're not
doing that when we export and sell, and we need to somehow replace those things,"
urges Beck.

Beck adds that growers have spent too many years adhering to tradition, doing
what is simplest. But as he puts it, a person will not change their eating habits
drastically until after their first heart attack. "Once it starts to change
in an area and you have a more efficient system that's making more money –
and no-till and diverse rotations in combination do that – you can start
paying more for land, whether renting or buying," reasons Beck. "Once
they start paying more for land, the grower using the old system won't be as
competitive and his choice will be to either change or quit."

According to Beck's numbers, obtained from Conservation Technology Information
Centre surveys, the impact in South Dakota has been remarkable. Potter County
is now 90 percent no-till and Sully County is 85 percent no-till, and all with
diverse rotations. "That's all happened in less than 14 years, with most
of that in the last five years, and all because economics have driven it,"
says Beck.