What is in this article?:
- Yields from N forms are very similar, studies show, although anhydrous ammonia is the most stable form. Apply your chosen form as close to plant uptake as your operation allows.
- Preplant spring anhydrous ammonia is the best bet for reducing N loss.
- Manure showed the highest economic gain over any other N form.
- Sidedressing as a primary fertilizer source has big advantages in wet years when it’s questionable whether a crop will be planted.
UAN offers sidedress flexibility
Frank Moore, who strip-tills corn and drills soybeans on about 2,000 acres in Howard County, Iowa, likes the flexibility that comes with sidedressing nearly all his N. “It was especially important this year. It was so wet so late in Howard and Mitchell counties that some people didn’t get any crop planted; I got only half the corn and soybeans planted that I intended,” Moore says.
“Anyone who had fall-applied N, or early preplant applied, lost a lot of that N with the heavy rains. And if they didn’t get a crop planted, they didn’t get any return from that expense of probably $60 an acre. In my case, when I couldn’t get the corn crop planted and took preventive planting through Federal crop insurance, I didn’t have the lost expense of unused fertilizer.”
Moore likes liquid N. He’s sidedressed nearly all his N fertilizer as liquid 28% UAN for nearly 10 years. “It may cost a little more, but I like the safety of using it compared to anhydrous, and I can drive faster to cover more acres,” he says. “Anhydrous knives aren’t compatible with the rocks we encounter in this area, either. Each form has its advantages, but I’m set up for liquid N with my equipment and it seems to be working for me.”
Moore’s Conservation Stewardship Program incentives and contract lock him into using no more than 30 pounds per acre of N on corn ground before planting. He broadcasts about 30 pounds of liquid N that helps act as a burn-down with his herbicide right after planting but before emergence. Then he uses the online Adapt-N program to determine how much N he needs to sidedress. That can be quite a bit. According to Ohio State University, corn N uptake can range from 4 to 8 pounds per day per acre between the V8 and tasseling.