Corn, Soybean Yields: What Does The Future Hold?

www.farmweeknow.com
Kay Shipman
2009-12-16

Yield contests demonstrate the ultimate achievement of farmer and seed, but increased knowledge continues to boost even average yields of corn and soybeans, according to University of Illinois and Missouri researchers during the recent Ag Masters Conference at the U of I.

Emerson Nafziger, U of I Extension agronomist, attributed some of corn yield gains to improved genetics. However, weather also plays an important role, and until recently Illinois “has a pretty good stretch of weather,” he added.

“Three-hundred-bushel (per acre) corn will need 33 inches of water (in the growing season). This year, we got more than 40 inches in some areas,” Nafziger said.

Crop rotation will improve a farmer’s chance of obtaining higher corn yields; however, that yield advantage appears to be diminishing, according to Nafziger. A corn-soy rotation still offers a 5 to 10 percent yield advantage over continuous corn, he noted.

High yields equate with high nitrogen in some farmers’ minds, but the “nitrogen rate is not the primary determinate for corn yield on highly productive soil,” Nafziger said.

Tillage is another factor, but Nafziger cautioned obtaining good soil conditions will be difficult next year. “Tillage will have little effect on corn productivity; the effect is the (soil) condition you put the seed in,” he explained.

U of I yield studies on higher plant populations have been inconclusive. Trial data would show that a farmer might expect higher yields on fields with more plants, Nafziger said.

However in 2009, researchers “got a very flat response on yields” from corn population studies in Urbana, he noted. Likewise, researchers have not found much of a yield response from cornfields with narrow rows, he added.

The number of soybean seeds -- not seed size -- determine yield increases, according to Bill Wiebold, University of Missouri plant science professor. “Focus on increasing seed numbers,” he advised farmers.

As for tweaking practices to increase soybean yields, farmers will find that to be more difficult.

“Remember yields are related to all year, not just one point. Yields are complex and change every day of the growing season. It is hard to isolate one management practice,” Wiebold said.

Farmers face different challenges in increasing soybean yields than with corn yields, according to Wiebold.

While corn growers can increase yields by increasing the number of plants to produce more ears, soybean growers have a difficult time increasing the number of pods per plant, he explained. When soybean plants are crowded in a field, fewer branches and branch nodes result, he said.

“The number of pods per plant drops as stand density increases,” Wiebold said. “In lower plant populations, there are many pods on branches.”

He advised farmers to focus on good farming practices. “No matter how great a farmer you are, you have to pay attention to the fundamentals,” Wiebold said.


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