News Corn Fertility and Nutrients
OMAFRA: Determining your corn MERN

Ben Rosser, corn specialist with Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA), has added another article to his series this spring on corn fertilization – specifically, on optimizing corn N levels while taking into consideration higher-than-usual input costs and uncertain availability.

The essentials growers should know about MERN:

• MERN stands for the “most economic rate of nitrogen” – the rate that maximizes economic returns on N fertilizer;
• MERN is influenced most strongly by variability in N response across environments (fields, parts of fields, growing seasons);
• MERN is also influenced by changes in corn and nitrogen fertilizer prices, but very significant changes in nitrogen:corn price ratios are required to change MERN appreciably;
• While calculating true MERN requires several N rates and software to fit N response curves, MERN can be estimated on-farm using the two-rate zero-N and N-rich “delta-yield” approach with the N Rate Evaluator tool at GOCorn.net.

For a more detailed description of what MERN is, how it functions, and how growers can use it to make on-farm decisions, visit the OMAFRA Field Crop News website.