Make nitrogen last
When you get in a squeeze, it's nice to have a few friends around. Despite high corn prices, nitrogen prices are putting the squeeze on a lot of corn growers this winter. Anhydrous ammonia that cost around $250 per ton in the Corn Belt six years ago was costing over $500 per ton last fall and was over $700 per ton by mid-January.
In an effort to protect expensive nitrogen, a lot of growers are taking a fresh look at nitrification inhibitors, urease inhibitors, coated urea, and other products that protect nitrogen from leaching, denitrification, and volatilization.
"High nitrogen prices make these products more attractive because it takes fewer pounds of saved nitrogen to offset the price of the additive," says University of Kentucky soil scientist Lloyd Murdock.
Michigan State University soil scientist Ron Gehl adds, "In years past, a somewhat common practice was for growers to apply a little extra nitrogen as a relatively cheap form of insurance. However, with high nitrogen fertilizer costs, many growers are looking for alternative strategies to assure adequate N is provided to the growing crop."
N-Serve nitrification inhibitor, a Dow AgroSciences product primarily used with anhydrous ammonia, has been around for 34 years. It delays the conversion of nitrogen from the ammonium form to the nitrate form and helps reduce nitrogen loss due to leaching and denitrification.
Think of it as insurance. Some years you need protection and some years you don't. But it's hard to know which is which ahead of time.
A 15-year study in Minnesota compared three treatments: Fall ammonia with N-Serve, fall ammonia without N-Serve, and spring ammonia without N-Serve. When yields were averaged across all 15 years, fall nitrogen with N-Serve and spring nitrogen without N-Serve yielded about 10 bushels per acre better than fall nitrogen without N-Serve. (Nitrate losses in drainage water were also reduced).
"However," says University of Minnesota soil scientist Gyles Randall, "corn yields were significantly affected by the N treatments in only seven of the 15 years.
"And," he adds, "when spring conditions were wet, especially in May and June, spring application gave substantially greater yield and profit than the fall N plus N-Serve treatment."
Extensive research throughout the Corn Belt indicates the response to N-Serve will be greater on poorly drained, fine-textured soils, sandy soils, and high pH soils.
Randall says, "The length of time N-Serve remains active in the soil before it degrades largely determines its efficacy. The period of inhibition depends primarily on when N-Serve is applied, soil temperature, and soil pH. In Minnesota when applied with anhydrous ammonia in late October, inhibition activity continues into May. When applied in mid- to late April, inhibition can continue into June."
Although N-Serve hasn't changed over the years, just about everything around it has. When nitrogen was 13Â¢ a pound, it cost a little under $4 to apply an extra 30 pounds. With nitrogen costing 39Â¢ per pound, it costs almost $12 to apply 30 more pounds. The recommended rate of N-Serve is one quart per acre, which costs about $8.