Genetics and management have to be used together.
The emphasis to have farmers consistently average 100 bushel per acre soybean yields has become a point of emphasis by soybean seed companies, university researchers and crop protection companies.
Emerson Nafziger, Extension agronomist with the University of Illinois, put out 2008 research trials using yield contest winner methods and his own concepts. Resulting yields were in the mid 60-bushel range-well above the projected state average but still short of the 100-bushel mark. There were, however, some yields of 80 bushels and above in parts of Illinois with more favorable weather.
Nafziger has doubts that we'll see that level of production across a broad cross-section of Illinois any time soon, though breakthroughs in genetics could make such yields more common.
Palle Pedersen, soybean specialist with Iowa State University, came close to producing 100 bushels per acre in his test plots this year. He's more optimistic about the broader potential for triple-digit yields, albeit cautiously so.
"Growers who are averaging 30 bushels or so are probably not going to make 100 bushels per acre-even in the next 20 years," said Pedersen. "But the ones who are producing over 60 bushels per acre now have a pretty good chance. What we're seeing coming down the pipeline from the seed companies is very promising, and I think there's a lot of potential. The missing link is management. Achieving 100 bushels per acre on a large scale is going to take proper management, there's no doubt."
"We've made great strides in advancing soybean genetics," said Mark Kitt, technical service representative, Syngenta Crop Protection. "But we also recognize that in-the-field management is just as important if growers are going to fully exploit the yield potential of the top varieties."
Steve Knodle, NK brand soybeans marketing manager, Syngenta Seeds, said, "Advanced genetics with season-long crop management is the cornerstone of the AgriEdge Soybean Program from Syngenta. It's an approach that encourages a higher level of soybean management with results. More than 5,000 growers enrolled in the program in 2007, and enrollment continues to grow since then."
The AgriEdge Program demonstrates to growers how yields and profits could be increased through more intensive management. The program encourages early-season weed control, field scouting and application of in-season treatments as needed of herbicides, fungicides and insecticides. Seed treatment before planting also can play a significant role. In 2007, AgriEdge Program participants averaged soybean yields of up to 30 percent higher than the USDA national average.
Unlocking Yield Potential
"If you don't plant at the right time and manage insects, weeds, diseases and other in-season pressures, if they reach the threshold for treatment, then you're just not going to get to that next level of soybean yield," said Pedersen. "We don't think twice about applying these concepts to corn, but the fact is that these basics are often overlooked in soybeans." As a result, growers are losing out on what Pedersen calls "easy bushels."
"These are the bushels we get from managing the yield-limiting factors-like aphids, bean leaf beetles and so on-that are within our control," he explained.
Still, the important management decisions like variety selection, planting date and row spacing have to be optimized, said Pedersen. In one of his test plots, he planted in late April on 15-inch rows, used a pre-emergence herbicide for early season weed control and then followed with two shots of glyphosate. He also used a seed treatment and sprayed for aphids. Yields came in at 92 bushels per acre. Why? Pedersen said he can't really explain.
"The yield potential in soybean germplasm is there," said Gene Kassmeyer, head of soybean product line, Syngenta Seeds. "Our R&D focus is now on integrating traits that will protect the seed we plant. We are continuing to evaluate NK brand soybean varieties with new sources for soybean cyst nematode (SCN) resistance. More than half of the products we sell today contain some type of SCN resistance and more acres each year are affected by this major pest. We also anticipate launching aphid-resistant varieties in 2010 coupled with a total integrated pest management approach that will provide the best solution available today for this troublesome pest. It's really about protecting the yield potential that is inherently present in our germplasm so that our customers can maximize their returns per acre and that is our focus at Syngenta."
Brett Begemann, excutive vice president, global commericial, Monsanto, contends that increasing soybean yields took a back seat to corn until Roundup Ready soybeans were introduced. Soybean yields have been increasing slowly compared to corn yields. "Up until about 10 to 12 years ago there was very little investment in soybean breeding," he said. "Soybeans are starting to see the kind of investment returns that corn has enjoyed for many years." The genetics for high-yielding soybeans continue to be improved.
Monsanto and Pioneer have announced the introduction of new high-yielding lines of soybeans in 2009. "Next year we will introduce the next generation of Roundup Ready 2 Yield soybeans, which will increase yields for farmers between 7 and 11 percent," Begemann said.
"That is nearly 10 years of traditional breeding yield gain in one step change from one product. So the investment in technology can make a huge difference" he said.
Beyond The Genetic Bushels
If some increases in soybean bushels are easy, then logic would have it that other increases in soybean bushels are difficult. These yield gains might result from managing more complex or overlapping problems, like a potassium deficiency coupled with aphid damage. They are also likely to stem from a better understanding of the interactions between soybean genotype and environment.
This is an area where there's a lot we still don't know, said Nafziger. He points to rotation studies conducted in Minnesota and Wisconsin as an example. When five years of soybeans followed five years of corn, the highest soybean yields came from the first crop year following corn; the second highest yield came from the second year of soybeans. Yields dropped off and flattened out after the third year.
"Farmers often see their highest soybean yields if they follow two or more years of corn, or if they grow soybeans for the first time ever in a field," said Nafziger. "A lot of pathologists would say that's probably due to a number of different soil diseases of soybean that are collectively nibbling away at yield potential when soybean is grown in a given field for a number of years." But, added Nafziger, that's hard to measure, as is the notion that first-year soybeans following five-year corn benefit from a build-up of residual soil nitrogen.
Speculation also extends to the role of light diffusion. Nafziger cited 30-year-old studies in which three-fourths of soybean leaves were shaded from light. The remaining quarter went into "pod overdrive," producing two times as much as usual. "This tells us that soybeans may be under challenged," said Nafziger. "They have the ability to crank up the rate of photosynthesis and produce more pods and larger seeds. The question is: how do we trigger that response under field conditions?"
Longer exposure to light and better light interception may explain why Pedersen's research consistently demonstrates a yield increase from earlier planting and narrow row spacing. In more than 50 planting date experiments conducted since 2003, earlier planting increased yield more than 80 percent of the time. Fifteen-inch rows increased yield by an average of 4.2 bushels per acre over 30-inch rows.
Steady Gains or Big Jumps
"We still don't understand soybean yield limitations well enough, and I think that may be because they come from different directions and there are enough of them that it's going to take time to quantify and qualify them," said Nafziger. He suspects that the largest yield gains will come from steady increments, such as Monsanto and Pioneer have announced plus disease and insect genetic control as Syngenta has announced, rather than a single big gain.
Next year, Nafziger and Pedersen will continue their quest for 100-bushel soybean production. In the meantime, the best advice they can give to producers is: choose the right variety for your field conditions and follow up with scouting and in-season management to protect yield potential. And ag retailers and crop consultants can be a big part of all those decisions.
Said Pedersen, "What farmers do to win a yield contest involves micro-managing, and we can't do that on a large-scale operation. But it does demonstrate that if you manage your crop, you can keep your yield potential up a lot. If we can just get farmers to move their yield potential up 10, 20, 30 bushels now and be careful about the details, then life will be good."
Article written by Editor Richard Keller and Linda Kane, Gibbs & Soell with assistance from Syngenta.
Genetics and management have to be used together.