Roots of the matter
The roots of a corn plant provide it with water and nutrients, but scientists know little else about the plant's life-sustaining tentaclesBY TOM BUTTON
Buried in their seedbeds, corn seeds are pushing out their first radicle roots to provide water and nutrients for the seedlings in their first critical weeks. From now until harvest, roots will be key to the crop's success.Yet roots are the least understood part of the plant. Scientists know very little about them, admits Thys Tollenaar, corn physiologist at the University of Guelph. "We can't answer even the most basic questions," he says. "Are roots limiting our yields? No one really knows."
Of course, there are specific field situations where the answer is obvious; for instance, when healthy looking crops start wilting at the first sign of drought, or when they blow over with the first gust of September wind.
Cathy Soanes, agronomist for Novartis Seeds, says growers have to make sure they're growing the best possible root systems using available genetics and weather. And the only way to be sure the job is being done right, Soanes says, is to head to the field with a shovel.
"If you don't get a good root system from the start, once you get into August you won't be able to fill those ears, especially if there's any stress," Soanes says.
Key to good root growth is soil tilth. Roots need moisture and air. They can't grow through saturated soil, or through soil that's hard as a brick. Compacted soils are a root system's worst enemy, whether that compaction extends all the way to the surface or whether it's a plow pan or deeper compaction that restricts root growth to the top few inches.
Often, growers are largely to blame, either because they worked or planted the soil too wet or they've dropped wheat and other fine-rooted crops out of their rotation. Mother Nature plays a role, too. A pounding three-inch rain, especially mid-June, can turn the top several inches of the soil into cement just when the crop is in the three- to six-leaf stage and trying to produce its nodal or "adult" root system.
Soanes digs roots throughout the year, but recommends that at minimum, growers take a shovel to the field when the crop is knee-high. Root systems should be at least a foot wide, with individual roots up to 18 inches long, and with lots of fine root hairs.
As the crop heads through summer, carry the shovel into the field to compare the roots in areas with stunted or unthrifty plants against roots in areas that are producing a good crop. Often, growers will soil sample those areas separately. But, says Soanes, problems in agriculture are often caused by several factors working together. Fertility might be partly to blame, but so might root restriction caused by working too wet or planting before the soil is fit. If so, solving nutrient imbalance won't cure yield loss.
Keep expectations realistic, cautions Greg Stewart, OMAFRA corn specialist. "Digging roots is a good diagnostic tool for large-scale symptoms," Stewart says. "It probably isn't going to tell you why one area is yielding 170 bushels and another is at 150."
Nor should a grower expect to plant a strip test of two different hybrids and then dig roots to tell which is a better choice for planting next year. Even the corn companies don't really know about the comparative rooting potential of their hybrids. Most times when a company says a hybrid has good roots, that means that it doesn't blow over, not that it is better than other hybrids at pumping water and nutrients to the leaves and ear.
Stewart doesn't fault the companies. Instead, like Tollenaar, he says that no one really understands roots. "It's my belief that, on average, the size of the root system doesn't limit yield, but the activity of the system does." In dry years, corn crops produce prolific root systems, but may still have poor yields. In wet years, root systems may be small, but yields can be astronomic. "We were paranoid about small root systems last year," he points out. "A lot of those crops went on to produce record yields."
Tollenaar has studied hybrids from the 1950s compared to their counterparts from the early '90s for traits ranging from the amount of leaf tissue they produce to their disease tolerance. He's only compared the root systems of two hybrids - Pride 5 and Pioneer 3902 - simply because it takes so much work to dig up an intact root system.
Those tests suggest that modern hybrids put out much bigger root systems, both in terms of the size of the root systems and in terms of the percentage of the overall plant that they make up. Breeders haven't been consciously breeding for big roots. "They can't, because they can't afford to measure the roots," Tollenaar explains. But over time, by breeding for bigger, more consistent yields, they've been breeding for better roots.
Tollenaar points out, however, that bigger roots come with a cost. Today's better roots, he believes, are a key reason why new hybrids get off to a slower start. Instead of pumping resources into leaves that can start to photosynthesize and help produce even more leaves, the crop devotes more resources to roots.
With new hybrids, roots start bigger and stay bigger through the entire year. It's a big reason why new hybrids are much less likely to root lodge in the fall. Still, if hybrids grew a root system that was just big enough, and no bigger than absolutely necessary, the crop would be able to devote more energy to grain production.
"When it comes to roots, all we're doing is guessing," Tollenaar says. "We don't have answers to 99.9 per cent of our questions."
While scientists debate whether they can afford to spend more of
their own
resources on learning those answers, Soanes suggests growers
should monitor
their own crops. "You can get some weird things like fertilizer
burn or
herbicide injury, but usually if there's a problem with roots, it
comes
down to soil management," Soanes says. "It's in the grower's
power to have
good roots."
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Bypassing the wheat pools
Ontario wheat board awaits approval for off-board selling from
Farm
Products Marketing Commission
BY TOM BUTTON
Wheat growers will be able to sell their wheat wherever they want next year if the Ontario wheat board wins its new bid to give growers a shot at total control over the marketing of their crops.The plan would let growers sell up to 150,000 tonnes (six million bushels) of this fall's crop. That's roughly 100,000 acres, or 15 per cent of an average crop.
Growers would have to sign a declaration at planting saying they would sell off-board. Once the paper was signed, the covered wheat wouldn't be allowed back in the pool.
Growers could sell the wheat wherever they find the best price, whether that's to domestic millers, U.S. mills or elevators, or overseas.
These and other critical program criteria are still up for grabs, however. So is the program itself, says Ken Nixon, Middlesex wheat grower and chairman of the Ontario wheat board.
"We want a go-ahead from the [Ontario Farm Products Marketing Commission] before we go any further," Nixon says. The wheat board has asked the commission for approval, but mid-April hadn't received a response.
The commission oversees the operation of Ontario's marketing boards. It must approve any major change in the way a board operates. Last year, the wheat board asked permission to set up a similar off-board system, with the proviso that all wheat marketed off-board would have to be exported to the U.S. The commission killed the plan when domestic millers said it would give Michigan mills an unfair chance to buy the Ontario crop.
"We had rounded third base and were on our way home before the commission told us we shouldn't have started running in the first place," Nixon says. "This time, we want to know where the commission stands before we go any further."
The new off-board plan has widespread support from wheat board delegates. It's also thought that because the wheat could be sold anywhere, and not only in the U.S., that most millers won't object.
"Speaking for Hayhoe Mills, we don't have any problem with it," says Ed Michaels, wheat buyer for the Woodbridge miller. "We see it as enhancing the industry by giving growers the option to sell their wheat the way they want."
Michaels foresees the board's pool price acting as a market minimum for domestic millers. If an individual miller needed more wheat than the board could deliver or if it feared prices would climb later in the year, the miller could post a higher price to lure in the off-board wheat.
Some years, however, growers holding off-board wheat may have to scramble to find markets. Ontario grinds about 350,000 tonnes of soft white wheat a year, but produces one million tonnes.
If growers get the go-ahead from the commission, Nixon says the board will appoint a committee to structure the plan. It's thought it would be a 10-person committee with five growers, two millers, two elevator owners, and a commission representative.
Several key issues need answers, including whether growers would
have to
switch their entire crop if they wanted to go off-board. Could
they split
their risk by marketing some each way? It's also unclear whether
the
authority to market off-board would function like a form of quota
that
could be transferred and perhaps even sold. The board says it
also wants to
be sure a reporting system is in place to keep track of sales and
ensure
the board gets its $1-per-tonne check-off.
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Price troughs dampen forward wheat
Wheat growers can expect to earn $3.50 a bushel for their
harvests this
summer. Some growers, however, will get paid more than $4.25 for
the same
quality wheat delivered on the same day.
Some can also expect to wait a year before getting final payment from the wheat marketing board, while others will get their total price within a couple of days of delivery.
The Ontario wheat board has introduced a range of new marketing tools that give growers much more control over their pricing and their cash flows. Included are forward contracts and cash-at-harvest plans, plus minimum pricing contracts and basis contracts.
Only a small percentage of growers have used the new tools, but that has more to do with recent pricing patterns than with their attractiveness.
So far, 660 wheat growers have forward contracted 33,000 tonnes for harvest delivery - roughly double the 1998 number. More may sign up, but board marketing manager Jim Whitelaw says it will depend on market performance.
Most of those with forward contracts are locked in at $4.25 per bushel or higher. About 300 locked in on a price surge last October. Another 200 signed up when Ontario prices rallied above $4 for a week-and-a-half in January. An extra 150 took advantage of a price peak in March.
Roughly five per cent of the Ontario wheat crop is forward contracted. Corn and soybean growers, by contrast, typically contract 30 per cent of their production before harvest.
"Wheat's different," says Colin Reesor OMAFRA marketing expert, Walkerton. "For us, winter kill is a serious risk; it's tough to take a position before you know you're going to have the crop to meet your commitment."
The wheat board has also opened the doors so growers can cash out of the pool and get their total price at harvest. In essence, it's an instant forward contract, with prices posted at the elevator or available daily through the board office. Growers who want to cash out must be sure to notify their elevator at delivery so they won't get their intial payment cheque. Next, they call the board to confirm the amount that they're selling. A few days later, they get the entire amount through the mail.
Few growers opted for cash last year, Whitelaw reports. Again, market conditions were poor. Indeed, the cash price was almost as low as the initial payment, so there was little advantage to selling.
That could happen again in 1999. Reesor, however, points out that cash sales for all crops are usually higher during periods of low prices.
Whitelaw is hoping the market will turn around before harvest.
"Right now,
the buyers' attitude is that there's no sense buying this week
when the
wheat will be cheaper next week," he says. "At some point, these
buyers
have to get back into the market." - Tom Button
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SEEDBED
By Keith Reid
Back to no-till basics
The fall of 1998 saw lots of ground blackened that hadn't seen a plow for years.We can argue about whether the yield losses were from no-till or from something else, or whether they existed at all, but that won't gain us much. I'm going to suggest that, in some cases, some of the basic rules that make no-till successful were forgotten.
Preserving soil tilth
On a mellow, well-structured soil, it's easy to grow good crops no matter what tillage system is used.Over the years, I've been amazed at how well no-till crops have done in some extremely tough conditions, but when you mix tough soils with tough weather, eventually the crop is going to suffer.
Crop rotation, cover crops and controlled traffic, along with no-till, will help to bring the soil into good tilth and keep it there.
Drainage and compaction
No-till soils don't lose as much moisture to the air through evaporation as tilled soils, so good drainage is critical. Tillage can help to compensate for poor drainage by opening up the top few inches of soil and drying them out: In no-till, this moisture has to be removed from underneath.The slow drying of no-till soils can also increase the risk of compaction. While no-till soils are firmer and will carry greater weight at a given moisture than tilled soils, they can still be compacted by traffic when the soil is wet.
Fertility
When we switch to no-till, we lose the opportunity to incorporate nutrients into the soil. This is the key reason why we've recommended phosphorus and potassium levels be built to medium or higher levels before starting into no-till. It's still good advice.It's inevitable that some fields are planted that are deficient in P and/or K. This leaves the uncomfortable choice of trying to grow a crop with insufficient nutrients, risking seedling injury by applying too much fertilizer through the planter, or broadcasting the fertilizer on top of the ground. None is ideal for consistently producing optimum yields.
Weeds and weed control
While weed control becomes more straightforward in no-till - we stop re-planting weed seeds with every tillage pass - it doesn't become less important. The burndown treatment is especially important to eliminate weeds that could have a head start on the crop. New herbicide options make rescue treatments possible, but by that time the damage has been done.
Residue management
Crop residue is the no-till farmers' greatest asset, but if it isn't evenly distributed over the field it can become their greatest headache as well. A residue strip left by the combine can act as a blanket to keep the soil cold and moist, so parts of the field are still too wet to plant when the rest of the field is ready.
Even more important is that the variability makes it impossible
to set the
planter properly, since the right settings for the chaff covered
areas will
be too shallow for the drier areas between the rows, resulting in
uneven
emergence.
Keith Reid is a soil and crop specialist (soil fertility) based
at
Walkerton OMAFRA kreid@omafra.gov.on.ca
back to May 3, 1999 Issue
Farmers embracing refugia recommendations
BY TOM BUTTON
Most corn growers who plant Bt hybrids are also planting the 20 per cent refugias that have been designed to prevent corn borers from developing quick resistance to the technology.When the 20 per cent rule was announced mid-winter, many skeptics believed growers couldn't be convinced to plant the non-Bt refugias. The thinking was that farmers wouldn't want to add an extra complication to their already hectic planting season, and that farmers who face borer pressure wouldn't want to give in to yield losses in their refugias.
"There's a good understanding of why we need refugias," says Ken Hough, research manager for the Ontario Corn Producers Association. "There will be the odd individual who won't pay attention, but the large majority are supporting the concept of resistance management."
Bob Jenkinson, former product manager for Novartis, has surveyed over 300 growers who have purchased Bt seed from the company for planting this spring. All but a handful, Jenkinson says, are going to plant refugia.
Overall, awareness of the resistance-management strategy was very high. Jenkinson found that over 99 per cent knew that they should be planting refugias, although many others weren't certain exactly how to go about it.
Like other seed companies, Novartis has been supplying refugia recommendations through its dealers and through publicity campaigns, and Jenkinson believes the message is getting through. Some growers will plant blocks of non-Bt hybrids, some will run non-Bt seed through three rows of a 12-row planter, and others are planting non-Bt sections with the goal of taking them off for silage.
Scientists such as Mark Sears, University of Guelph entomologist and chair of the Ontario Corn Borer Coalition, say corn borers can mutate and produce individuals that can survive on Bt corn. In order to pass that resistance on to the next generation, however, the resistant borer must mate with another resistant borer.
If the entire crop was switched to Bt hybrids, Sears adds, the only borers to mate with would be borers that were also resistant: All the others would have been killed off. The pair would mate, producing a new generation of resistant borers.
Refugias work by ensuring there are non-resistant borers for any resistant borer to mate with. The progeny would then have middle-strength resistance, and still be killed by the high doses of protein in Bt hybrids.
Without refugias, Sears says, resistant borers could overwhelm the Bt technology in as little as five years. With refugias, the technology should keep working at least two to three times as long.
Companies including Pioneer and Dekalb are requiring Bt buyers to sign a pledge that they will plant a 20 per cent refugia. Both of the companies and Ottawa say they will monitor compliance after planting.
Novartis marketing manager Doug Knight predicts the industry will
find a
high rate of refugia compliance. "The growers understand why
refugias are
necessary," he says. With planning during the off-season, there's
also no
need to make planting overly complicated, Knight says. "The
coalition was
able to make the rules quite flexible."
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Soys surging in South America
Seven years ago, few Argentinian soybean growers had ever used
fertilizers
or herbicides. Now, they're adopting Roundup Ready faster than
their
Ontario amigos - and posting yields as high as 60 bushels per
acre.
In the '90s, Argentina's annual soybean output has soared to 475 million bushels - six times Canadian production. And millions more Argentinian acres are ready for their first soybean crop.
Still, Argentina has a much bigger neighbour. Brazil is producing 900 million bushels a year - second only to the U.S., which averages a crop of two billion bushels. But Brazil is just getting started. In its central Cerrados region, farmers are planting 24.7 million acres to soybeans. The outlook is for 148 million acres of soybean planting, with crops as high as three billion bushels.
"South America is going to be the world's biggest soybean producer - there's no doubt in my mind," says Kim Cooper, marketing specialist for the Ontario soybean board, who toured the region this winter.
Similar jumps lie ahead for grains, including corn, adds Brain Doidge, economist for the Ontario Corn Producers Association. "We need to focus on building domestic markets," Doidge says. "There's going to be huge competition on the export markets when these big crops come on line."
Because of new varieties and better use of fertilizer and herbicides, yields are climbing rapidly. In both countries, soybeans average 36 bushels per acre, within an eyelash of North American averages.
Cooper foresees a steady stream of yield hikes as growers get better at fertilizer management. Growers are also making strides with no-till and are coming to grips with pests including the soybean cyst nematode.
Currently, Argentina is the world's leading exporter of soybean meal and soybean oil. Second is Brazil. Both countries are also aggressively seeking export markets for raw beans for crushing.
"I'm not full of doom and gloom," Cooper says. "We're finding
more and
more new uses for soybeans...Brazil and Argentina will be bigger
forces,
but I don't see the North American soybean marketing going down
the drain." - Tom Button
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