Should agronomic practices focus more heavily on soybean production?

Growing soybeans more intensively raises crucial new questions

In the mid-2000s, a spirited discussion between a private-sector crop adviser and a public-sector employee working in extension reflected the disparity that existed between corn and soybean production. At the time, corn yields were climbing at a stronger pace than soybeans, despite the arrival of glyphosate-tolerant soybeans.

The adviser suggested that more had been done by the private sector to boost corn yields than the public sector was able to do for soybean yields — a take on the “what have you done for me, lately?” taunt.

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It was an unfair comparison then: soybeans had recently been decimated by drought, excessive heat and the explosion of soybean aphids in 2001. Plus, an expansion of weed species and diseases, together with the spread of soybean cyst nematode in subsequent years further hampered the same upward progress on yield as had been enjoyed by corn.

It didn’t help that soybeans had also acquired a reputation of “it takes three (environmental) strikes to hurt your soybean yields.” That was the same as giving the industry permission to ignore the crop and let it fend for itself.

Today, it’s still an unfair comparison, primarily because the two crops are so different in so many ways — one is essentially a hybrid grass, the other a varietal legume. One is a monocotyledon, the other is a dicot. The growing points, nutrient demands, vegetative and reproductive stages, and unique sink (grain storage) structures — all are different.

But what if the same intensity of agronomic and biological management practices used in corn was applied to soybeans? It’s arguable that soybean production parameters have lagged behind those of corn up to the last five years. Corn’s reputation as the driver of farm revenue is almost unassailable, pushing soybeans into the back seat, despite the fact that soybean acres have eclipsed those of corn in Eastern Canada since at least 2011.

Yet the rationalization continues. Soybeans are supposed to be able to tough it out on their own. Or, if you look at it from the opposite direction, there just isn’t supposed to be as much return from pushing soybeans as from pushing corn.

33 factors in all

Eric Richter wants to change that line of thinking, and he has at least 33 ways to start. At a workshop attended by Syngenta seed growers last January, Richter spent part of the afternoon session exploring the many facets of soybean production. During breaks between presentations, he began writing down the parameters as they came to mind. Some were more obvious — like ideal row width, canopy closure, nutrient uptake amounts and timing — while others were part of a strategic renaissance, addressing overall production parameters, whether they’re seen as corn concepts or soybean ideals (see the complete list here).

“The concepts and ideas are not ranked, weighted or grouped in any way, but they need to be, and that’s the next step,” says Richter, who has studied soybean plant biology and production parameters for nearly 30 years. He’s quick to note that many of the ideas are not original, nor are they exclusively his, but more a summary of production concepts and techniques he’s gathered over the years. Some have come from growers, some from researchers and some Syn-genta’s product development team, includ-ing David Lee and Don McClure, respectively Syngenta’s long-serving soybean senior technician and breeder.

Initially, Richter wrote down 31 facets he deemed noteworthy and came up with a 32nd parameter after the workshop, while the 33rd was added as the 2015 growing season progressed. But he also points out that these facets represent a series of starting points on their own, and he continues to add to this list and knows there are many more that can still be added.

Two terms he’s particularly emphatic about are “bean flex” and “G x E.” He characterizes bean flex as the ability of a soybean plant to generate additional yield very late in the bean-fill stage — as a function of seed size. Richter has been using this term for years, yet as far as he knows, it’s an agronomic term particular to soybeans that does not exist in any research literature or publication. Recent Syngenta soybean data confirms the importance of bean flex with up to 30 per cent of yield bonus being derived from bean flex in a high-management soybean trial.

Although corn and soybeans are different plants, it doesn’t mean growers can’t employ the same management practices in soybeans as they do in corn.

Although corn and soybeans are different plants, it doesn’t mean growers can’t employ the same management practices in soybeans as they do in corn.
photo: File

As for G x E (or ‘G by E’), it encompasses the relationship of the Genetics of the seed with the Environment into which that seed is planted. But it’s more than the seed-to-soil link: it’s also soil type, weed, pest and disease species and spectra, weather conditions, and fertility levels. In short, it’s everything involved with where, how and why the seed is being planted.

Although it’s not a new concept like bean flex, it is something that Syngenta was first to acknowledge (as part of the company’s “The right bean for the right land” campaign in the mid-1980s). Yet G x E is just as relevant today as it was back when Richter started his career. And the layers of information that can be added are limited only by the advance of precision ag applications, including yield monitor information and yield maps.

“What I try to say to growers is that if you look at G by E, and if you understand and capitalize on that concept, you can add about 15 per cent yield without doing anything radically different other than really positioning the varieties to the best fit,” Richter says.

Still the disparity

It’s something Richter put a lot of thought into during his near-30 years in agriculture. He has taken portions of what he has learned working in forages —including the creation of the Forage Masters distinction — and tried to determine why soybeans have been neglected. One sign of that neglect is the relative disparity between theoretical and actual (in-field) yields in both corn and soybeans, and he asks why the two are so different. In corn, the gap is the 500-plus bu./ac. theoretical versus about 170 actual (Ontario provincial average), which is roughly 34 per cent of theoretical yield. In soybeans, that gap is at least 15 per cent lower — 250-plus bu./ac. theoretical versus 45 to 48 actual (Ontario provincial average), which translates to 18 to 19.2 per cent.

“Corn is relatively easy to grow, but soybeans — it’s a very complex crop in so many aspects, and the spoils go to the detail-oriented soybean grower,” says Richter. “I find it interesting that many growers list slow genetic improvement of soybean germplasm as one of the main limitations to improving on-farm soybean yields, when it’s actually their current soybean production systems that are failing them. Many growers are managing soybeans today, exactly the same as they did 30 or 40 years ago. Why?”

Richter also believes more yield is lost by the cumulative effect of diseases and pests, a factor worsened by bean-on-bean or continuous-bean cropping. Hence the placement of the pest and disease limiting factor as first on the list: years ago, McClure convinced him that too much yield is lost  because growers underestimate those impacts.

Current production trends

In many ways, these are also a reflection of the default approach growers have taken in the past 10 years. The advances of researchers and plant breeders in selecting from elite germplasms and breeding those high-end performing hybrids and varieties have led to something of a letdown in production methods. Growers are expecting 300 bu./ac. corn yields more on the strength of the performance of the seed without necessarily doing all they can to help improve the health of the soil.

Bean flex is a relatively new term that refers to the plant’s ability to generate additional yield late in the bean- or pod-fill stage.

Bean flex is a relatively new term that refers to the plant’s ability to generate additional yield late in the bean- or pod-fill stage.
photo: File

Richter points to five such factors that should be fairly obvious, but have fallen off the radar for growers — for any of a number of reasons. Those are: soil health — specifically relationships to those cropping systems that include tight rotations of soybeans; limitations of the “Scavenger Crop” concept; planting date for soybeans — what is the optimum time; managing extreme residue levels to maximize seed emergence and establishment, and implications from excessive planting rates of soybeans.

These are fundamental in their nature, yet with the job the seed and trait companies have done in bringing innovations to the field, many of these concepts, especially in soybeans, have not just become secondary — many have been ignored outright.

What’s old is new again

The concept of growing soybeans with the same enthusiasm as with corn is certainly worth repeating and sharing. Richter concedes that the overall principle behind it — what he calls the “crop management intensity concept” was something he encountered nearly 30 years ago when he was working in forage research. When he began working as a sales agronomist and moved into row crops, he found that same approach and many of the same concepts applied to soybean production.

“It was amazing travelling the back roads and being able to identify forage producers who stood out within their area as true Forage Masters,” he says. “My work term with soybean growers has taught me that the same concept applies to soybeans just as much as to any forage crop — it’s all about the details.”

Next, look for more in this series on enhanced soybean production in future editions of Country Guide.

This article was first published in the October 2015 issue of the Soybean Guide

About the author

CG Production Editor

Ralph Pearce

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