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Do seed treatments boost your beans?

There are scores of seed treatments on the market used for reducing stress, stimulating growth and bumping yields in soybeans. But farmers need to know whether they actually work and are worth the extra expense.

That’s what Michael Rethwisch, University of Nebraska Extension educator at Butler County, was hoping to learn in his research plots at Northeast Nebraska Community College in Norfolk and near Waverly this past season.

Seed treatment products on the market work in different modes, Rethwisch says. Some like nematicides, fungicides and insecticides kill pests. Inoculants are live biological organisms like bacteria or fungi that are added to seed with the purpose of entering a symbiotic relationship with plants, increasing nutrient uptake and warding off pests.

At a glance

Numerous products on the market aim at stimulating soybean growth.

Rethwisch found that seed treatments often enhance yield potential.

It appears inputs like starter fertilizer are needed for more production.

“By definition, a biostimulant is a substance — a hormone, extract or molecule — from one or more biological organisms that results in a stimulus in a different organism,” says Rethwisch. “These stimuli often result in faster growth, systemic activated response [SAR] or increased flowering, respiration or ion uptake.” Some products are actually combinations of two or more products in these categories.

Research projects were carried out in 2010 on seed treatments or applied in furrow at planting time at both locations. At the Waverly site, plant height, chlorophyll levels, trifoliate leaves, trifoliate nodes and/or pods per plant during the growing season were all higher on plants treated with numerous stimulant substances on the market.

“Growth enhancement products tested helped soybean plants to get off to a better start in 2010,” Rethwisch says. So yield potential was enhanced in midseason evaluations, but final pod counts and production on the Waverly site were equal for the treated and untreated plants, he says.

At the Norfolk site, where inoculants were evaluated with and without starter fertilizer, trifoliate nodes throughout the growing season were greater in those plots that had starter fertilizer. Pod numbers were increased in midseason when receiving both inoculant and starter fertilizer at the beginning of the season, compared to the plants that only received fertilizer or inoculant treatment, which were similar to each other. Yields at the sandy Norfolk site were enhanced primarily by fertilizer, although a slight increase was noted with the addition of inoculants, Rethwisch says.

He noted that a pattern existed in soybean growth in 2010. “Early growth which increased nodes was associated with increased pod numbers,” he says. “Seed treatments help to increase yield potential. However, to realize actual yield, additional inputs, such as increased fertilizer, will be necessary to capture potential yield increases.”

In 2011, Rethwisch and other UNL Extension researchers will be duplicating these trials on new fields. They are now looking for new farmer-cooperators.

For more information, you can contact Rethwisch at 402-367-7410 or e-mail him at


MORE POTENTIAL: Mike Rethwisch, Butler County Extension educator, displays soybean plants that received different treatments during 2010 trials at field plots on the campus of Northeast Community College in Norfolk.

This article published in the March, 2011 edition of NEBRASKA FARMER.

All rights reserved. Copyright Farm Progress Cos. 2011.