Disappointed with no-till?
Poor-performing no-till crops have some farmers scratching their heads and considering dusting off their plows, but there's lots to considerBy TOM BUTTON
With crops coming off so early and so fast, it's hard not to second guess whether moving into no-till was the smart thing to do. But maybe it wouldn't be such a bad idea to get out the plow.The year's no-till crops have proved disappointing. Most crop watchers expected the spring's warm, dry soils would be a boon to no-till crops, getting them off to a strong start. By late summer, however, growers across the province were unhappy with their no-till corn, and even their no-till soys. That's why many farmers are expected to rip up fields they've had in no-till for the last three to 10 years.
But committed no-tillers are preaching caution. Before plowing, consider the impacts on soil structure, fertility, weed pressures and earthworms.
"We have absolutely no intention of plowing," says Bob McKinnon, who farms 1,800 acres with his brothers near Port Huron, right in the middle of the worst drought region.
McKinnon first tried no-till in 1991 and now no-tills 95 per cent of the family's fields, with soils ranging from blow sands to heavy clays. Right after harvest every year, McKinnon asks his crop insurance agent for township yield records, so he can tell how his management package stacks up against conventional plow cropping.
"What we're doing is working," McKinnon says. Yields this year will be low because of the drought, but that's also true of plowed fields. In fact, McKinnon thinks no-till crops held onto their colour for a couple of weeks longer than plowed fields before finally running out of moisture. Even if no-till yields did drop below plowed yields, "I'm not going to change based on one year."
But if other growers do plow up their no-till fields, what should they expect next year?
"Higher yields," says OMAFRA crops adviser Rob Templeman. But Templeman cautions it's a one-year phenomenon.
Busting up a no-till field is like busting up a long-term sod, he explains. The superior soil structure and the sudden shot of air can combine to produce some of the highest yields a farm might ever see. Trouble is, the soil quickly loses its no-till structure and within about a year is back suffering the same problems as when it was plowed year after year.
The height of the yield spike depends on how long the field has been in no-till. If it's been just a couple of seasons, the yield bonus will be so small it may not be noticeable. If the field has been no-tilled for five years or longer, it could be five to 10 per cent and maybe more.
Most no-tillers report, however, that their soils get more mellow and easier to no-till, with better yields, the longer the field has been no-tilled. In other words, if you plow, the number of extra bushels you get next year is linked to the number of bushels you'd be giving up in long-term no-till production.
The issue of potash stratification is less clear. Unlike nitrogen, potassium doesn't leach through the soil: Instead, it stays where it's put. In no-till, if potash is surface applied, the potash level in the upper one to two inches can get very high while it falls in soil lower down.
Tom Bruulsema, Ontario rep for the Potash and Phosphate Institute, says the jury is still out on whether stratification is reducing yields, and therefore whether it would be a good idea to periodically plow no-till soils to spread the potash through the soil profile.
Most research to date suggests that corn and soybean roots are able to get all the potash they need from the stratified layer, Bruulsema reports. He's watching the results of new University of Guelph trials to see whether potash uptake may be restricted in years like 1998 when that upper layer is very dry.
Few growers rely on a pure no-till system. Instead, most use a multiple coulter system to work up an in-row seed bed at planting. That tillage could help spread the potash.
As well, Bruulsema says, techniques such as shallow or deep banding may be equally effective as tillage at placing the potash where it's needed, just as no-tillers use 2 X 2 bands at planting to apply phosphate. More research is needed, Bruulsema believes.
University of Guelph weed scientist Clarence Swanton is warning that growers who plow their no-till soils should prepare for several years of tough weed control.
Weed control gets easier the longer a field is left in no-till, Swanton says. He studied the seed bank in soil at Fingal with eight-year side-by-side no-till and plow plots. No-till plots had an average 4,400 weed seeds per square metre in the top six inches: plow plots had 54,000.
Swanton explains no-till leaves weed seeds on the surface where they can be eaten by birds and rodents or turned to mush by disease.
While no-till soils may get hit harder by perennial weeds, Swanton argues that weed control is actually easier in long-term no-till soils. No-till gives growers lots of opportunity to hit perennials pre-plant, pre-harvest and post-harvest.
As well, because no-till leaves weed seeds on the soil surface, they all tend to germinate at the same time, making it easier to get effective control with a single post-emerge spray with a non-residual herbicide. In plowed fields, the deeper range of seed depth means weeds come up over a longer period and therefore need more expensive residual control.
"Plowing a no-till field is almost always the wrong thing to do," Swanton says. "From a weed control perspective especially, it's going to do more damage than good."
A single year's plowing will also devastate earthworm populations, says Cathy Fox, scientist for the federal agriculture department at London. In her studies in Essex County, long-term no-till soils that boasted an average 170 earthworms per square metre had only 22 worms per metre the year after they were plowed. At the same time, Fox learned earthworms boost soil productivity by moving nutrients and organic matter through the soil profile.
The plow may kill some worms by cutting them in two. More damaging, Fox says, is that the plow disrupts their network of burrows.
Like most scientists, Bruce county's McKinnon believes that every
year he
stays in no-till, his soil gets healthier. "The longer you're in
no-till,
the more it pays off," he says. "We're not going to rush in and
set
ourselves back."
back
Soy key to better health
But can the industry convince consumers to eat enough of its
protein-packed products?
BY TOM BUTTON
Baby boomers are lining up at drug store counters with prescriptions to fight their high cholesterol levels. New studies, however, show they should be popping soybeans, not pills.Soybeans are a miracle food for fighting heart disease and cancer. According to David Jenkins, professor of medicine and nutrition at the University of Toronto, soybean growers will be making one of the great humanitarian contributions to human health when they can convince North Americans to eat more beans.
Jenkins cites a growing mountain of evidence showing that soybeans are chock full of compounds that can prevent not only cancer and heart disease, but will also curb osteoporosis and soften many symptoms of menopause.
"The soybean is our key source for all these active ingredients," says Jenkins, adding that the reason why Japanese residents on the island of Okinawa have the world's top longevity is that they eat so many soybeans in their daily diets.
Many Canadians consume large amounts of soybean products, but mainly via oil products such as margarine and cooking oil. To get the medical benefits, they must eat the protein, and that's where the marketing challenge lies.
Peter Golbitz, editor of the U.S. soybean industry guide, Soy BlueBook, says that corporate boardrooms have already figured out there will be a boom in the health market for soybeans. Golbitz says that explains why drug company DuPont has joined with Pioneer, and why Monsanto merged with American Home Products, one of the world's largest drug companies. Archer Daniels Midland has also announced it will build a U.S. plant to process soybean ingredients for health-conscious food supplements.
In Ontario, Ken Bee, chairman of the provincial soybean marketing board, is equally optimistic. "We have the potential to increase our sales to North Americans by 1,000 per cent," Bee says.
Jenkins says the evidence supporting soybeans is overwhelming, even though researchers need to do more studies with humans, not just lab animals.
Jenkins points to tests showing that humans fed a mere 43 grams (1.5 ounces) of soy protein a day had a 12 per cent decrease in levels of harmful LDL cholesterol, while their beneficial HDL levels weren't affected. The result is a significant shift in the critical ratio between the two compounds, "and a significant benefit for cardiovascular disease prevention."
What's uncertain is how consumers will eat their soybeans. Despite repeated efforts, North Americans haven't accepted traditional Asian ways of eating soybeans, such as tofu, natto and miso.
John Mullins thinks the soybean industry shouldn't give up.
Mullins, a
food scientist at the federal agriculture department's research
station at
Harrow, says Canadians will change their attitudes if they see a
health
bonus. He points to yogurt. A decade ago, Canadians turned up
their noses
at the thought of yogurt. Today, it's one of the most popular
snacks for
children and young adults.
back
SEEDBED
By Keith Reid
Structure key to soil success
Soil structure is the pattern of large and small holes created by the way the soil particles clump together. This mixture of big and little pores determines how well excess moisture drains away, how much available moisture is held in the soil, and how easily roots grow through the soil.An ideal soil structure has been likened to a rich, moist chocolate cake. Soil that looks like this will drain quickly in the spring, plant easily, keep crops growing through dry weather, and consistently produce good yields.
Wheels off!
Keeping traffic over the field to a minimum will go a long way to
maintaining good soil structure.
Driving over a wet soil will cause much greater compaction than the same traffic over a dry soil. Here's why. The water in the soil forms thin films over the soil particles, acting as a lubricant so the particles can slide past one another. In dry soil, friction will keep the individual particles in place, so the dry soil can support a much greater weight before it compacts.
Since we can't always wait until the soil is completely dry before traveling over the field, the next step is to minimize the weight of equipment. Tandem axles or tracks reduce the weight pressing on the soil for the same payload. The axle weight of tractors must be managed to keep it as low as possible, while avoiding excessive wheel slip, which can cause more damage than a greater weight pressing straight down.
Minimizing the number of trips over the field will also prevent compaction.
Rotation
Continuous growing of any single crop will degrade soil
structure;
continuous row crops are worst of all. A sound crop rotation
includes crops
that leave large quantities of crop residue behind, and crops
that have
fibrous root systems to bind soil particles together. Mixing the
crops up
also means that roots get into different parts of the soil.
Ideally, the rotation should include forage crops, with a mix of deep rooted legumes and fibrous rooted grasses. Plowdowns can fill the same role. These crops will also keep a cover on the soil, protecting it from rainfall impact.
Unpaid employees
The real job of creating soil structure is accomplished by the
millions of
unpaid workers you never see: earthworms, mites, fungi and
bacteria. These
creatures mix raw organic materials with the soil particles,
sticking them
together into stable granules that don't break down with the
first rain
shower.
To do their job, these workers need enough material to work with, as well as a hospitable place to live and grow. The raw materials can be any organic matter, including crop residues, green manures or livestock manures. A hospitable home will include a proper mix of air and water, and room to move. Keeping the soil pH up is also essential for a healthy soil fauna.
Tillage: yes or no?
Advertisements for equipment sometimes talk about "creating" soil
structure through tillage. While it is true that tillage can
fracture the
soil into a desirable mix of large and small granules, it cannot
ensure
that this mix is stable. Crusting, and poor crop emergence,
happen because
these granules break down under rainfall. A well-structured soil
should
remain open and friable even after heavy rain.
Tillage can be useful for mixing organic materials into the soil so it is more readily accessible to soil organisms. The old style of clean plowing, however, does just the opposite by hiding the residue at the bottom of the plow layer, where the organisms can't get at it. Residue left on the surface will eventually get mixed in with the soil by biological action, although it will take a little longer than with a disc or cultivator.
Too much tillage can decimate the earthworm population and leave
the soil
open to erosion and runoff. In order to maintain as much of the
soil's
natural structure as possible, the general rule for tillage is
the less the
better.
Keith Reid is an OMAFRA soil fertility and crop specialist
kreid@omafra.gov.on.ca
back to October 5, 1998 Issue