WOOSTER, Ohio — Incorporating legumes into a crop rotation to capture the fixed nitrogen for the corn crop is one way Ohio growers can combat high fertilizer prices.
Robert Mullen, an Ohio State University Extension natural resources specialist with the Ohio Agricultural Research and Development Center in Wooster, Ohio, said that the cropping system might be an effective alternative to investing in commercial fertilizer. Mullen, along with other OARDC researchers, will be conducting studies beginning this spring to measure the amount of nitrogen that is produced from such a cropping system and to place a dollar value on the production practice.
"There's no way around it. Corn needs nitrogen and growers know they are going to have to deal with the high costs of fertilizer," said Mullen. "As a result, how much growers invest in fertilizer will be impacted; many will most likely be buying less than they typically do. The question that remains is how will that impact the corn crop?"
With the price of oil increasing (currently over $53 dollars a barrel), the use of natural gas as an energy source has become an attractive option for the energy sector. The result is a trend of increased nitrogen and phosphorus costs over the past several years.
"It's encouraging to know, however, that growers are finding ways to manage those high costs and finding different ways to apply fertilizer," said Mullen. "The alternative cropping system is a potentially viable production practice that some growers have switched to."
Some production systems in Ohio maintain a corn-soybeans-wheat rotation. The idea behind the alternative cropping system involves over-seeding a legume, such as red clover or a type of vetch, into the wheat crop in the spring, allowing it to grow over the summer as a cover crop, then killing it off in the fall so that the nitrogen fixed by the crop is available for corn planted the following growing season.
Legumes contain symbiotic bacteria in their roots. The plants provide nutrients for the bacteria and, in turn, the bacteria fix atmospheric nitrogen the plants can use. When the plants are killed off, the organic nitrogen housed in the roots and above-ground plant biomass is eventually broken down into an inorganic form that becomes available for the corn crop. Additionally, the legume, as a cover crop, offers conservational benefits, most notably, decreased soil erosion.
A more direct, efficient way of managing fertilizer applications is to sidedress the corn crop — a process of delaying application until the plants have emerged (anywhere from the V-3 to the V-8 leaf stage of a corn crop). Mullen said that most growers are already proficient in this management practice.
"As growers know all too well, spring can get fairly wet. When you have a coarse, sandy soil, with wet conditions, you can lose a considerable amount of nitrogen through leaching. With heavier, clay soils, the structure of the soil is such that you can lose nitrogen from the surface as a gas by denitrification," said Mullen. "With prices higher than they have ever been before, it makes it tight for a grower when you are only dealing with $1.80 per bushel for corn. Sidedressing provides growers an opportunity to potentially save on fertilizer costs."
Ohio State researchers will be conducting their studies on red clover in an alternative cropping system at OARDC's Northwestern and Western research branches.