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Sulfur needs often overlooked in soybeans

Soybean research at Purdue University is showing sulfur is a key nutrient to higher soybean yields.

Purdue Extension agronomist Shaun Casteel…

“Most people would say I don’t need it for soybeans,” he says, “but sulfur is actually a cofactor for nodulation, and so if we don’t have nodulation, we don’t have good nitrogen supply. We don’t have good yields.”

Unfortunately, Casteel says naturally occurring sulfur is declining…

“We have the Clean Air Act in 1990.”  He says, “You know, we started to realize that instead of getting 15 to 20 pounds of sulfur being deposited from the atmosphere, we’re at less than 5 lbs. And so now it’s starting to be not much from atmosphere. It’s got to come from the soil.”

He says when adding the nutrient, timing matters.

“We’re planting earlier than we used to.”  He says, “The soils are cooler, and so the microbial activity is limited. We need sulfur as soon as you have root hairs for nodules for the bacteria to infect. So earlier plantings are ones that I’ve seen some really remarkable responses. Even on good Prairie dirt.”

Casteel says there are several sources of sulfur commercially available and encourages growers to discuss the nutrient with their agronomists.