Friday, April 15, 2011
Are You Applying Nitrogen At The Most Profitable Rate?
The fall of 2010 had the most accommodating weather for agriculture in the memory of many farmers. Harvest was completed in a timely manner. Fall tillage followed. And a lot of nitrogen went on before the machine shed doors were closed. Because of the high volume of nitrogen that has already been applied, a smaller amount than usual has been applied this spring, and it is uncertain how much corn will be need to be side dressed later in the spring. However, if nitrogen application is still on your checklist, there are some changes that you need to know about that may have an impact on how much you spend or don’t spend for 2011 nitrogen application.
Some farmers have been applying nitrogen at the same rate year after year, but others have been adjusting their application based on its price and the price of corn. That practice has come to be known as application based on the “maximum return to nitrogen.” In other words, since nitrogen is an input that has a cost, ensure that it is making the most possible amount of money by increasing yield when corn prices are high, and putting less on when corn prices are low. No, you don’t have to have a pencil and paper to work it out, because Iowa State University has a web-based decision aid that accommodates the farmers in IA, IL, IN, MI, MN, OH, and WI.
Your job is to select your state and, in some cases, your location in the state, then enter the price of nitrogen and the price of corn. The calculator will do the rest. You may have used it before, but the data has been changed, and the answers you received last year may not be the answers you receive this year. Iowa State University fertility specialist John Sawyer says with the new data from last year, the calculated nitrogen recommendation rates have increased slightly from previous years. You have the choice for obtaining a recommendation whether you have corn following corn or corn following soybeans. The decision aid will provide a specific rate in pounds of nitrogen per acre, but also a range which is a range of profitable nitrogen rates that provide a similar economic return to nitrogen with $1/Acre of the maximum return to nitrogen.
Another fertility specialist who has weighed in on the application rate is Fabian Fernandez at the University of Illinois. His recent newsletter reminds you that corn does not need a lot of nitrogen at the outset, and 30 pounds per acre or so will be enough to get it going until a late spring sidedress application is made. If you applied nitrogen last fall, Fernandez provides some comfort about its continued availability, “For those who applied N in the fall, so far this year conditions have been favorable to preserve it, and I suspect that as long as fall applications were done as recommended, there is little need to worry about N loss to this point.” Fernandez recommends the use of the Iowa State calculator to help determine your application rate based on the potential for profitability.
Fernandez expressed some concerns with early pre-plant applications, if excess moisture delayed planting while the soil was warming up. That means nitrification and the loss of the nitrogen to the corn plant. Think back to last year, and Fernandez said everything started out right, “Last year, for example, was one of those years when soil conditions were ideal for early preplant N applications, but after a few weeks of warm and dry weather, soils became saturated with water. Under those conditions we observed that using a nitrification inhibitor, such as N-Serve, or polymer-coated urea, such as ESN, helped protect N from loss compared to urea or anhydrous ammonia without N-Serve.” From planting on, those inhibitors are not needed. He also cautions that if anhydrous ammonia is applied when the soil is too wet, the sidewall may smear from the knife and the gas escapes unimpeded.
Summary:
Springtime application of nitrogen should be adjusted to the rate that will return the profit to the nitrogen. That will depend on the price of nitrogen, the price of corn, and is available from a web-based decision aid with information updated from the 2010 crop. Anyone applying nitrogen this spring should be cautious of the loss to denitrification and use an inhibitor if corn planting is still some time away.
Posted by Stu Ellis on 04/15 at 12:00 AM | Permalink