By Carolyn King
We know it’s possible for corn in Ontario to yield over 300 bushels per acre under special conditions. For instance, Ontario growers have produced 300+ bushels on single acres in yield contests. And in 2010, four hybrids yielded over 300 bu/ac at one site in the small plots of the Ontario Corn Committee (OCC) Hybrid Corn Performance Trials. But what would it take for high-yielding corn fields that today produce 200+ bu/ac to routinely reach 300+ bu/ac?
It’s an intriguing question that has researchers, agronomists and corn growers discussing and testing the possibilities, including an on-farm study that is now underway.
By Carolyn King
Learning from the trends
One way to figure out how to further increase yields is to look at how we’ve got to where we are. As growers know, corn yields in Ontario have been trending upwards for many decades. The average yield is now about 150 bu/ac. In the last five years, many growers have had fields yielding over 200 bu/ac.
“Three things influence where we’re at in terms of corn yield: genetics, environment – especially the weather – and agronomics. But to try to fine-tune comments around those things is very difficult,” says Greg Stewart, corn industry program lead with the Ontario Ministry of Agriculture, Food and Rural Affairs. He notes that each of those factors is continually changing and they all interact with each other, so it’s difficult to separate out their relative importance and to determine which particular changes in each factor are the most important.
Looking at the agronomic component, Stewart says: “Most growers have improved their agronomics around corn planting by planting earlier or planting into more uniform seed beds and/or using better planters with precision seed placement. That has contributed to yield increases, although you can argue about how much.” Other practices, such as fungicide applications and higher plant densities, have also helped, but he suspects their contributions to the yield trend have been relatively small.
In fact, according to Stewart, the evidence shows agronomics has played only a small part in yield trend. For instance, the agronomic practices in the OCC trials have changed very little over the last 20 years, while yields have climbed significantly.
To figure out whether genetics or the environment is the most important factor, Stewart examined OCC trial data for the hybrid Northrup King 3030Bt over a nine-year period. “Strangely enough, that hybrid’s yields increased during that time. Since the agronomics and genetics stayed the same, you’d have to credit that increase to better environment, better weather,” he says. “So, what percentage of the yield does the weatherman get credit for versus the corn breeder?”
Dr. Bill Deen, an agronomy researcher at the University of Guelph, notes the corn yield trend line for the last 10 years has been much steeper than the trend line for previous decades. Whether the steeper line is a temporary blip or the start of a new trend, he is curious about which factors might have caused the greater yield increases in the last five or six years.
Deen thinks improvements in genetics and management, such as better planter performance and more uniform tillage, have contributed in part to that steeper line, but changes in weather patterns might be very important. He speculates that analysis of weather data might show trends over the last half-decade such as possibly warmer temperatures in August and September, warmer nighttime temperatures, earlier springs, and/or changes in rainfall patterns.
When Stewart looks at the last five or six years, he notes several years with some of the highest total heat units on record. Like Deen, he would be interested in seeing the results of a detailed analysis of such weather characteristics as nighttime temperatures. But Stewart also thinks another factor in the steeper trend line may be the effect of increasing adoption of hybrids with European corn borer protection.
Although Deen expects genetics and management will continue to improve incrementally, he’s not sure if those advances will be enough to get today’s 200-bushel fields to 300 bushels. However, one management area he thinks might offer a real opportunity for further improvement is soil quality.
Soil quality is important for things like nutrient and moisture uptake by the roots and soil moisture retention. As well, Deen says, “There are some classic studies demonstrating that, even if moisture and nutrients are non-limiting, yield is still increased if a corn plant has a well-developed, fibrous root system. Why that is, we’re not sure. But soil quality promotes that rooting pattern.”
Examples of practices that improve soil quality include crop rotation, cover crops, and controlled traffic systems to reduce compaction.
There’s a lot of debate about what input levels, especially nitrogen (N) levels, are needed for higher corn yields. Although Deen has data from one of his current research sites showing an economic response to quite high N rates in 2010 and 2011, his past research and many other studies show that N rates significantly above the recommended rates don’t necessarily pay.
“The whole idea around increasing inputs will be an interesting one to wrestle with,” says Stewart. “Nitrogen is hugely controversial. The nitrogen recommendation systems for most of the states in the U.S. have now taken yield goal out of the equation. For instance, the Iowa State University Corn Nitrogen Rate Calculator doesn’t ask how many bushels per acre you think your field can generate. It asks whether the previous crop was corn or soybeans, and what the prices are for nitrogen and corn. Then it tells you the average optimum N rate [for the maximum return to N]. In Ontario, our nitrogen calculator still has a yield expectation component. So if your expected yield is 300 bu/ac, then our calculator would ask you to apply a lot more N than if the expected yield is 180.”
High-tech package for higher yields
Dr. Fred Below, a crop physiologist at the University of Illinois, has spent much of his career evaluating different options to enhance corn yields. Like Deen and Stewart, he sees environment, genetics and management as the key factors in improving yields, but he’s willing to put some numbers on how much each contributes.
Based on research in Illinois, Below has developed a tool called “The Seven Wonders of the Corn Yield World” to help farmers and agricultural professionals evaluate corn management options. “Our Seven Wonders are those factors each year that can have a big, positive impact on corn yield,” he explains. “It’s a catchy deal that farmers can relate to.”
The tool first identifies three essential prerequisites for good corn production: good weed and insect control; drainage; and proper pH and adequate phosphorus (P) and potassium (K). Then, assuming those basic criteria are met, the tool ranks the top factors affecting corn yields, expressing their relative value in bushels per acre.
The most important is the weather (70+ bu), followed by nitrogen (70 bu), hybrid selection (50 bu), previous crop (25), plant population (20), tillage (15) and a catch-all category called growth regulators that includes such practices as fungicide applications (10).
So, the idea is, if all seven factors are optimized, a farmer would get 260 bu/ac. To go from 260 to 300 bu/ac, the farmer would need better prerequisites.
Below has taken this concept a step further. “Using our knowledge of how individual factors impact corn yields, we’ve put together a high-tech package where we try to optimize as many of those factors [as possible] at the same time in the same place.”
He explains, “Basically our high-yield package is feeding and protecting a higher population of the best genetics.” The package has five components: improved soil fertility, including additional P, sulphur and zinc; a triple-stack hybrid; side-dressing with an extra 60 lb./ac of N over a base N rate of 180 lb./ac, with the side-dressed N in a form that is designed to reduce N loss to the environment; a high plant population of 45,000 plants/acre; and a fungicide application, such as Headline, for plant health and harvestability benefits.
A key finding from Below’s research is that the components of the high-tech system work together. “We’ve found a synergistic effect of combining the individual factors — the combined effect is much bigger than you’d expect based on the individual value of those things one at a time.”
Below has come very close to reaching 300 bu/ac on some of his high-tech plots. “I’ve sometimes had a single plot in a treatment go a little over 300 bushels, but I’ve haven’t had a replicated treatment reach 300 bushels. However, I’ve been in the high 290s and I’ve routinely seen some 250s and 260s. I largely blame the weather, of course, when I don’t reach 300! And it usually is the weather, in all honesty.”
Does the high-tech package pay on-farm? “It’s a very difficult question to answer because the value of the grain changes daily and the price of the inputs tends to change often as well,” says Below. “To buy more seed and apply more fertilizer and protect it all with a fungicide, it’s not a cheap endeavour. I’d say usually you’d need to produce somewhere in the range of 30 extra bushels to be able to pay for it. But that’s not a hard and fast answer because, for instance, if grain is $7, then the high-tech package almost always pays.”
Looking ahead, Below says, “I think we’ll be seeing 300 bu/ac as fairly routine in the next five to 10 years due to technology advances. That includes biotechnology – better genetics, better protection, ultimately drought-tolerant hybrids – and better fertilizer and application technologies, and better protection technologies. If you combine all those together, there’s a huge payoff down the road.”
Aiming for 300+ on high-yielding Ontario corn fields
To see if higher-input practices would make economic sense for high-yielding corn fields in Ontario, Pride Seeds launched its 300+ Bushel Initiative in 2011.
“With this study, we wanted to look at recent advances in traits and genetics, farmers’ practices, and equipment a bit more closely to see if we could push yields even further,” says Ken Currah, central market development agronomist with Pride Seeds. “We’re hoping to develop a standard set of recommendations that could be tweaked slightly for each grower’s situation, so we can say here’s how to make the best potential out of growing our product.”
In 2011, the initiative involved about a dozen field-scale sites with growers in eight counties in Ontario. All the sites were high-yielding fields, with 200+ bushel expected corn yields.
The sites included a range of soil types, but all had proper pH levels and adequate to abundant P and K. Many of the co-operating growers also routinely apply other nutrients such as sulphur and magnesium. The growers each have their own approach to N applications; for instance, some use a single application and others use split applications. All sites included some type of tillage. At most sites, the previous crop was winter wheat or soybean, except one that was second-year corn. The growers are using Pride’s top-of-the-line hybrids with key trait combinations and treatments.
At each site, the growers used their own equipment and their standard practices. Then on a 10-acre portion of their field, they used a set of higher-input practices: higher seeding rates, higher N rates, and a Headline fungicide application. BASF is co-sponsoring the initiative with Pride Seeds.
In the 10-acre test area, the target plant populations were 10 to 20 percent above the grower’s standard rate. For nitrogen, the grower’s standard rate, usually about 160 to 180 lb./ac, was compared to a higher rate of 200 to 220 lb./ac and a very high rate of 250+ lb./ac. Headline was applied at tassel emergence in the 10-acre test area.
In 2011, much of Ontario’s corn-growing region had a prolonged, cool, wet spring that resulted in very late planting. But that was followed by good growing conditions in most regions, and many areas were frost-free right to the end of October.
Due to the poor spring weather, stand establishment was highly variable, and it was impossible to evaluate the effect of plant population in 2011.
The results were positive for the higher N rates. “The higher N rates provided a positive return on investment at all locations, averaging about $70/acre compared to the grower’s standard nitrogen rate. And even the very high N rates had a positive return,” says Currah. “The 2011 results suggest that, for high-yielding fields, nitrogen rates could be increased by about 10 to 20 percent.”
The fungicide application also had a positive return at every site. “The benefit ranged from 6 to 30+ bushels,” notes Currah. He adds, “In research studies, [fungicide application] doesn’t pay every time, but in our case it did. That is interesting because our sites were high-yield potential fields put into aggressive management. I think there’s a correlation, that if we use Headline to keep the plant healthy in a high-yielding environment where it has been fed and managed aggressively, there is a higher opportunity for payback with a fungicide.”
He emphasizes, “All these inputs dovetail together. We have growers who ask us about plant population – ‘Should I try planting 36,000 instead of 32,000?’ My first question to them is, ‘What are you going to do to help those extra 4,000 seeds along? Are you going to fertilizer more, use fungicide?’”
For 2012, the initiative again involves about a dozen growers and follows similar methods. With the growing season getting off to a much better start than in 2011, Currah is looking forward to seeing the results.
He adds, “It would be great if we had a 300-bushel field in this Initiative, but it is maybe more satisfying if we could show our customers how to get from 210 to 260, than if we get the guy with the really sweet 260-bushel soil from 260 to 301.”