You may not grow 100-bu soybeans anytime soon. But you can grow 60-bu beans without making big changes in your production program, soybean experts say.
The national average yield for soybeans is still in the upper 30-bu/acre range. Where climate and soil allow, local and even some state averages have climbed above 50 bu.
Given the variability of weather and the genetic ability of current soybean varieties for specific regions, most extension soybean specialists agree that yields could be higher.
First, growers should be quicker to switch to new, more productive varieties. Too often, a grower finds a variety he likes and stays with it a year or two longer than he should. The newest varieties, both private and public, should outyield their older counterparts, say the experts.
Lanny Ashlock, University of Arkansas extension soybean specialist, says growers commonly ignore the need to inoculate soybean seed when planting ground where the crop hasn't been grown in many years. He expects even better, more aggressive strains of nitrogen-fixing bacteria to be developed that will enhance yields further.
Ashlock encourages growers to study their management practices.
"Growers with yield monitors report occasionally seeing very high yields - 80 bu or more per acre - in some parts of fields," he says. "Once they determine why some areas yield more than others, maybe they can change management so the entire field will produce that much."
Dick Cooper, a USDA-ARS soybean researcher at Ohio State University, believes field mapping and other precision farming techniques will allow growers to change varieties to match field conditions and increase overall yield averages. He suggests planting semidwarfs in high-yield areas and taller, drought-tolerant varieties on drought-prone soils.
If a grower has selected the best available genetics in the correct maturity for his farm, just two other factors need to be emphasized, says Jim Beuerlein, Ohio State extension agronomist. Planting date and row spacing are responsible for half the final yield of a field, he says.
"If soil moisture and all inputs are adequate, then growers need only drill beans in narrow rows as early as the soil allows," he says.
Disease control accounts for 20% of yield, according to Beuerlein. Growers may not be able to economically justify intensive disease control using multiple fungicide applications, but they can select disease-resistant varieties using university performance-trial reports, he adds.
Don't count out fungicide use, though. Beuerlein suggests scouting fields and then using economic threshold information available from your extension service or seed company agronomist to find whether disease control costs are justified.
Beuerlein says 15% of final yield depends on adequate weed control. He recommends that growers begin with a low-cost program aimed at their most troublesome weeds. The need for spot spraying or rescue treatments should be determined by weighing the cost against the possible yield gain.
Soil fertility is responsible for only 7% of the final yield. Beuerlein says growers need to pay the most attention to pH and potassium. But unless they're way out of line, most other management practices should get higher priority.
Last on Beuerlein's list of management factors is seeding rate, which he says is responsible for just 5% of yield. But 5% can make the difference between a loss and a reasonable profit. He tells growers to check actual seed drop and calibrate planters or drills closely to the desired seeding rate, rather than merely setting sprockets and chains according to a number in the operating manual.
"Soybeans are better at adapting to mistakes in seeding rates than most other crops," he says.
Still, too low a rate can reduce yields and a too-dense stand wastes money, plus it can lead to lower yields if moisture or nutrients are limited. Also, diseases like white mold thrive in dense stands where air movement is restricted, Beuerlein says. ?