More main-stem nodes is one advantage Jake Vossenkemper (right), Pioneer agronomy trials manager, found in an early season soybean plot on Greg Plunk’s farm near Mansfield, Ill.
Growers dare to boost soybean yields by planting early
Greg Plunk is a betting man. This spring, he’ll plant soybeans as early as soil conditions allow. Neither threat of frost, nor hail, nor conventional wisdom that corn should be planted first will keep him from his appointed rounds.
In 2011, a soybean plot on Plunk’s Mansfield, Ill., farm showed a 5-bu. to 7-bu. yield advantage to early planting across a range of varieties and maturity groups. Planting dates were April 15, May 15 and June 1. A full-season variety planted on April 15 topped the plot at 96 bu. per acre with no irrigation. The entire site, part of a Pioneer Hi-Bred study, averaged 67 bu. in a summer when the word "dry" stuck to the roof of the mouth of every farmer in the area.
Plunk was so impressed with the results that he has added a new 24-row planter to his machinery lineup. This spring, he’ll be able to simultaneously plant corn and soybeans. "I’d like to be planted by April 25. Wet springs have been a problem the last few years, and waiting for the right soil conditions is important too," he says.
"Late frost is a concern with early planting, but the odds of a killing frost are two out of 10 years in this part of central Illinois. A 20% chance of replant is worth the risk to significantly bump yields,"
Proven advantage. Most university researchers around the Corn Belt agree that early planting is part of the formula for producing high soybean yields. Mike Staton, Michigan State University’s Extension soybean educator, notes that farmers who have topped the Michigan Soybean Yield Contest since 2006 have planted two weeks earlier, on average, than the lowest-yielding entries. Data also shows that the high-yielding entries average 10 more pods per plant.
University of Nebraska research shows that for each day planting is delayed beyond May 1, soybeans lose 0.6 bu. per acre under good growing conditions and 0.25 bu. per acre in years with poor growing conditions. "There’s an advantage to planting soybeans in the last half of April or early May compared to mid-May or later planting dates," says James Specht, a University of Nebraska agronomist.
Specht likes to think of the timing risk in terms of expected date of seedling emergence rather than planting date. "Study the probability of late-spring freezes in your local area and consider that, by a conservative estimate, about seven days to 10 days will pass after planting before the seedling emerges," he says.
Beyond freezing temperatures, risks of early planting include soilborne diseases such as pythium. Soybeans generally take longer to emerge when soils are cold. Early planted soybean seedlings also have a higher probabil-ity of experiencing feeding from bean leaf beetles and sudden death syndrome (SDS).
Second looks. Jacob Vossenkemper, a Pioneer agronomy trials manager based in Tuscola, Ill., initiated an early planting management study in 2011 because he thought that more local on-farm
research was needed to validate the feasibility and potential yield gains of early planting.
He planted a short-season and long-season cultivar at early, normal and late timings in 17 on-farm strip trial locations across Illinois and Indiana. The value of seed treatments and the possible need to alter varietal maturity to accommodate early planting were also part of the focus.
"Early planting allows soybeans to initiate reproductive growth sooner and grow reproductively during the longest days of the year, when sunlight is the most intense. This is key because sunlight capture and soybean grain yield are closely related," Vossenkemper says.
"We noticed a significant increase in nodes per plant, which increases the potential for more pods per plant," he continues.
Plant nodes are where the plant produces its flowers, then pods and, ultimately, seeds within those pods.
- Mid-February 2012