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Basic training for the best soybean yields

High and higher soybean prices not only bid for acres, but also recruit new growers in the battle for more soybeans. New growers may need basic training upon joining the ranks. That applies also for those returning to soybean production, as grassland farmers become crop growers. Veteran growers can learn also.

There are many steps in a growing season that can add bushels to year-end harvests. Every extra bushel per acre will be worth added dollars. Any mistake that costs bushels becomes more expensive.

Bill Wiebold, a University of Missouri Extension crop scientist, continues to see missed opportunities in fine-tuning soybean production.

Key Points

New and returning soybean growers should review basic steps.

Beans on new ground need inoculant. Get the right one.

Don’t skimp on seeds, but note that overplanting results in hitting a plateau.

“The most overlooked profit potential is failure to inoculate seed for plantings on CRP [Conservation Reserve Program] or cropland out of soybeans for three years or more.” he says. “Proper nodulation of soybean roots adds nitrogen in the air available to plants.”

Not needing to add N fertilizer is a cost-saving factor in favor of soybeans, vs. corn. Pick the inoculant specific to the soybean roots. Be sure to follow the directions contained on the seed label, Wiebold says. Driving by fields, if you see soybean leaves lighter green than those in neighboring field, that’s a clue on lack of nodules. Dig to do a nodule count.

Invest in seed

New growers may suffer sticker shock when pricing soybean seed. “Don’t skimp on seed. Plant enough seed to ensure 110,000 plants per acre in all parts of the field for a full-season crop,” Wiebold advises. Field trials at Columbia show yields plateau above 110,000 plants per acre. On the other hand, boosting the number of seedlings per acre above 110,000 may not be a good investment.

Unlike corn, soybean plants fill in the rows with added branches to grow more pods. That ability to branch can save what looks like a sparse stand. Give a weak stand a chance. An early-planted sparse stand can out-yield a late-planted thick stand.

“Don’t replant, except in cases of complete failure,” Wiebold says.

Still, there’s a limit. This brings up row spacing. Narrower rows will grow more bushels than the old-time 30-inch rows. There is little difference between the 7.5-inch and 15-inch rows.

There are times for planting more seeds per acre. Early season, especially when soils are cold and wet, requires more seeds. Soybeans are a warm-soil crop. In cold and wet soils, more seedlings rot and die. It’s the stand, not seeds per acre, that counts. Also, more seed is needed for late-planted or double-crop beans following wheat harvest.

Seeing double

Expect to see more double-crop this year. More wheat was planted last year, and wheat growers will be tempted by the higher soybean price. The late-planted soybean plants don’t have as much time to fill in the rows to set those extra yield-boosting pods. Whenever possible, use no-till on soybean plantings. In comparison plots at Columbia since 1996, no-till yielded more than tilled plots every year except one. Overall average was a 3-bushel-per-acre increase. No-till boosts yields, but more importantly, it protects a farm’s main asset: the soil. That’s worth more.

Soybeans respond to tweaking; at current futures prices, even partial bushel tweaks are worth dollars. Keep in mind that with rising input costs, that there may be a difference between an agronomic boost and a profit boost. Add the low-cost tweaks that add big boosts first. That includes the inoculation.

Soybean checklist to boost yields

1. Pay attention to weed control. Use two-pass rather than one. Early shading stunts growth.

2. Select high-yielding varieties for your area. Pay attention to available disease-resistant genes.

3. Plant more seeds — up to 150,000 — July 1 and later.

4. Plant early to shoot for maximum yield potential.

5. Use narrow rows.

6. Rotate away from soybeans every other year.

This article published in the March, 2011 edition of MISSOURI RURALIST.

All rights reserved. Copyright Farm Progress Cos. 2011.