Secret to 190 bu/ac soybeans: Pound in nutrients until beans cry uncle

By Connor Lynch
Farmers who’ve heard tell of the 190 bushel per acre soybean record set by U.S. grower Randy Dowdy last year could be forgiven for thinking: Why aren’t I getting yields like that?

The answer, from University of Arkansas researcher Larry Purcell, who tried Dowdy’s recipe for super soybeans, might not be what growers were hoping to hear but were probably what many were expecting: Pile on the nutrients way past where it’s making you money. Unfortunately, the single best way to boost soybean yields is also the least feasible for growers.

Purcell’s research, which produced roughly 100 bu/ac beans, saw his crop gobble up huge amounts of nutrients, including 500 lb./acre of nitrogen. To get Dowdy’s record-setting 190 bu/ac, he figured growers would have to essentially double that nitrogen investment. “Tremendous amounts of nutrients we’re talking about here,” Purcell noted.

While yields were boosted tremendously by the massive nutrient infusion, that defeats half the reason producers grow soybeans, OMAFRA soybean specialist Horst Bohner told Farmers Forum. Part of the profitability of soybeans comes from the fact that you don’t have to feed them like corn.
Can growers achieve even 150 bu/ac in a commercial soybean field without breaking the bank? Bohner was blunt. “No, we can’t.” But 80 bu/ac beans is not a fantasy in Ontario.

Purcell’s research suggested that about 25 inches of annual rain were needed for 100 bu/ac beans. According to the Meteorological Service of Canada, that’s about 12 inches fewer than Western Ontario’s seasonal 30-year average from 1980 to 2010.

Bohner offered three main points to maximize soybean yields: Plant a high-yielding, long-season variety as early as you can in a field with good nutrients; protect your yield potential with a fungicide or herbicide; and pray for rain in August.

Even 100 bushels per acre might not be beyond a well-prepared and lucky producer. “In the past, we used to always say these guys from Arkansas and Missouri, their world is so different,” Bohner said. “Their heat units are so much greater than ours that we can’t even compare yields.” But competitive growers have broken 100 bu/ac yields in Ontario, and growers in similar states like Michigan have gotten as high as 140 bu/ac, he said. “Certainly the potential is there in our genetics and growing area. It’s not all just about moving down south.”