Right on the line
Gary Robbins knows how to walk the line. His Jackson County farm sits right on the line between corn country and wheat country in the Flint Hills region of northeastern Kansas.
That means wheat yields of 80 bushels per acre are fairly common these days versus generally fair-to-average corn and soybean yields.
"If we get anywhere over 125-bushel corn and 30-bushel beans, we think we're doing pretty well," Robbins says.
But in the last few years, because of high and rising row-crop profit potential, anything that can help boost his soybean yields is a chance for Robbins, a member of the Successful Farming magazine High Yield Team, to turn the tightrope he's on into much more solid footing.
He found one new way to boost yields in his latest soybean crop, a 96-acre field he enrolled in the High Yield Team program with a goal to take yields from 40 to 60 bushels per acre.
In Robbins' case, it boiled down to close attention to a few landscape characteristics unique to his area. At his farm, the rolling hills' soil chemistry can sometimes present a challenge.
"I was having problems with yellowing beans because we've got some 7.5 to 8 pH soils around here," says Robbins, who grows corn and alfalfa and operates a small cow herd besides his soybean and wheat acres.
He sought a combination of solutions to his high-pH soil problem. On top of applying a foliar fungicide, Robbins in 2006 tried a manganese supplement. The goal was to offset the effects of the soil pH that creates a deficiency in both soil and plants and caused his beans to yellow.
Manganese deficiencies, like in Robbins' fields, are common in sandy, poorly drained soils. In soybeans, chlorosis occurs in the absence of enough of the nutrient, according to Purdue University Extension soil fertility specialist James Camberato, causing leaves to yellow.
Application efficacy depends largely on the stage of plant growth and when a shortage of manganese is detected.
"Foliar applications can be really effective -- some in rates as low as two tenths to half a pound per acre," says Camberato. "Application is best anytime you have enough foliage for the liquid to contact. The leaf surface area is most important."
In some extreme cases of soybean manganese deficiency, however, more than 15 pounds per acre are required when the problem is detected later in the growth cycle. And, in cases when a deficiency is detected in early-growth stages, foliar applications are less effective.
"If you have a plant with just one leaf on it, it can't take much in," Camberato says. "Sometimes the deficiency is severe enough that the plant starts out low, so the foliar applications arenâ€™t good for that."
Foliar exposure wasn't an issue for Robbins, who surface-applied around three pounds per acre of manganese directly to the soil surface around planting. While it ultimately paid dividends, he says his application could have been much more effective.