Iowa State University Extension and the Iowa Department of Agriculture & Land Stewardship are reminding farmers and fertilizer dealers that the Corn Nitrogen Rate Calculator is available online and it is a very useful and worthwhile tool to use. The tool can help farmers find the maximum return to nitrogen fertilizer applications and the most profitable rate of N per acre to apply for their farm.
The Corn Nitrogen Rate Calculator can be found on the ISU Extension website. This online tool is always updated to allow for changing hybrid genetics, rotations and climatic conditions. The Iowa database in the calculator was updated in 2012 with 2011 response data and now contains 214 trials for corn following soybean and 111 trials for corn following corn.
"Having adequate nitrogen available is critical for corn production, but given the high prices for fertilizer it is important farmers determine the right amount of nitrogen that is needed to apply to their crops," says Iowa Secretary of Agriculture Bill Northey. "Every farmer wants to make sure the corn plants have the amount of fertilizer they need while not over applying—that's what helps make this calculator is a great tool."
Nitrogen rate calculator tool can be used for corn-bean as well as corn-on-corn rotations
The calculator can be used for both corn and soybean rotations and corn-on-corn operations. It allows farmers to compare up to five price ratios – pricing options for nitrogen and corn. Farmers can reach out to their local fertilizer suppliers to find current fertilizer prices. The calculator then lets farmers determine the optimal rate of nitrogen application that is needed based on up to four different corn prices.
"Nitrogen application rates determined by the calculator are the total nitrogen fertilization amounts for each crop rotation. There is no need to further need to adjust the application rate for previous crop," says John Sawyer, soil fertility and nutrient management specialist with Iowa State University Extension in Ames.
Sawyer reminds farmers they should also wait until soil temperatures remain below 50 F before applying anhydrous ammonia or NH3 fertilizer this fall. A statewide real-time soil temperature data map is maintained by ISU Extension and Outreach at the website and can be used by ag retailers and farmers to determine when fall nitrogen applications are appropriate.