-- PLANTING DATE: Research has shown clear yield penalties for late planting. Conley's Wisconsin-based research shows, on average, a nearly 0.4 bushel per acre (bpa) yield loss for every day growers plant past May 1. "For every 10 days past May 1, we lose 4 bushels of yield," Conley said.

Research from other states has shown that this figure stands true for much of the Soybean Belt. University of Nebraska agronomist Jim Specht has long held that on average, soybean yields drop a quarter bushel per acre per day after May 1 in poor growing conditions and as much as three-quarters of a bushel per day in good growing conditions.

-- CROP ROTATION: Soybeans respond very positively to rotation, Conley said. A continuous 30-year rotation study in Wisconsin shows a steep drop-off in average yield when beans are planted after beans more than two years in a row. The average yield of first-year soybeans (rotated immediately from corn) was 61 bpa. The average yield for second-year soybeans dropped to 57 bpa and then 53 bpa for third-year soybeans.

-- ROW SIZE: Research shows a definite yield penalty to wide-row soybeans (30 inches or more), Conley said. Data from across the country shows yield gains ranging from zero to almost 18% when growers go to narrow row soybeans, which Conley defined as 22-inches or fewer. A rise in inputs such as seed treatments and fungicides might have masked that penalty in past years by increasing plant health, but those inputs are better spent in narrow row beans, he added.

Wisconsin research from 2008-09 also showed that narrow rows could save producers up to a week of time when it comes to weed control by closing canopies faster.

-- SEEDING RATE: Research from Seth Naeve, Extension agronomist for the University of Minnesota, showed that lowering soybean seeding rates had a higher yield penalty in 30-inch row spacing versus 10-to 20-inch spacing. The narrow row fields also had less yield variability than the wide row fields, Conley added.

That complements Conley's seeding rate research, which has shown that the likelihood of a farmer breaking even with $8 soybeans is highest when fields are planted as low as 103,000 seeds per acre. That may be a little low for many soybean producers' tastes, so Conley is pushing growers to drop seeding rates to at least 140,000 seeds per acre, and -- if possible -- using a variable rate planter to drop more seed in low-productivity spots in the field and less seed in areas where soybeans thrive.

-- SEED TREATMENTS: Increased profitability with lower seeding rates is mostly possible because of base insecticide and fungicide seed treatments, Conley noted. While seed treatments are technically an added cost, they are increasingly a standard part of seed company offerings and one that most growers are already paying for.

Wisconsin research shows an average yield benefit of up to 2 bushels per acre from seed treatments, but only for early-planted beans, which face a higher risk of disease. Once the planting date slips into late May and early June, that yield response disappears. As a result, cutting seed treatments on late-planted fields could actually be a good way to save on inputs, Conley said.

-- WEED CONTROL: The hard truth is you can't save on weed control right now, Conley said. Herbicide-resistant weeds spreading across the country have made pre-emergence herbicide passes more vital than ever. What you can do is make aggressive weed control a priority input, because it is certain to pay off. Research has long shown that weed competition quickly and permanently depresses yield potential. "That's why it's very important that in a down economic year, when growers are looking at minimizing their inputs, they not cut out their pre-emergence herbicide and they definitely don't cut it in half and go with a half-rate," Conley urged. "Go with a full rate of a pre-emergence herbicide with multiple modes of action."

See Conley's video on YouTube here: http://bit.ly/…

Emily Unglesbee can be reached at Emily.Unglesbee@dtn.com

Follow Emily Unglesbee on Twitter @Emily_Unglesbee

(PS/BAS)

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