GHGMP News Releases

Recommended rates of nitrogen application may be more than is needed

Indian Head, Sask., September 8, 2004

Ontario corn producers who follow standard recommended rates of nitrogen application may be applying more than what is considered optimal, says a field crops specialist.

The discovery was made at the start of a project evaluating different soil nitrogen tests and application rates in 2003, says Brian Hall with the Ontario Ministry of Agriculture and Food (OMAF). Results showed that optimal fertilizer rates are less than the standard recommended rates most corn producers use.

"It may mean producers are able to reduce nitrogen rates and in doing so, there could be a lower risk of surplus nitrogen being leached through the soil or lost to the atmosphere," says Hall.

Further evaluation of the fertilizer application rates will continue through to the 2005 growing season on nine demonstration sites across Ontario. The project is being partially funded by the federal Greenhouse Gas Mitigation Program for Canadian Agriculture (GHGMP). Soil Conservation Council of Canada administers the soil and nutrient management component of the program. A longer report on this project can be found on the SCCC Web site at

The demonstrations involve testing the soil using four different nitrogen assessments: a pre-plant nitrogen soil analysis; an in-crop test called a pre-side dress soil nitrogen test; a corn stalk nitrogen test that measures nitrogen in corn plant tissue near the end of the growing season; and a fall soil test analysis. Hall says nitrogen testing at various stages of the growing season will provide a clearer picture of the amount of nitrogen actually available and used.

"Right now most producers are following provincial recommendations for crop nutrient requirements and are also taking into account how much nitrogen is in the manure that's being applied," he says. "What most producers are not taking into account is the amount of organic nitrogen that's mineralized in the soil during the growing season."

The pre-side dress soil test may be the one of the most valuable to producers if it is proven to be accurate, says Hall. The test is done at the four to six leaf crop stage to show the amount of available nitrogen in the soil. If the test is accurate, producers will be able to determine the amount of nitrogen needed in-crop to support the corn over the balance of the growing season.

Checking nitrogen at various stages will also help determine how much surplus nitrogen is left in the soil at various fertilizer rates. "The tools may help producers reduce application rates and input costs, as well as the amount of surplus nitrogen in the soil," says Hall.

The GHGMP supports a broad range of projects across Canada with the goal to promote awareness of agricultural practices that reduce greenhouse gas emissions. SCCC administers the delivery of the soil and nutrient management sector component of the program. For more information on activities, visit the SCCC's Web site at

For more information, contact:

Brian Hall, Field crops specialist
Phone: (519) 271-0083

Doug McKell, P. Ag.
Executive Director, SCCC
Phone: (306) 695-4212
Fax: (306) 695-4213