Internet-based nitrogen rate guidelines for corn production

Agriculture and Natural Resources Extension
Iowa State University

Extension Lead(s)
(name, position, counties served, contact information)

John Sawyer
Extension Soil Fertility Specialist
Soil Fertility Research and Extension
2104 Agronomy Hall
Ames, IA 50011

Your Position


POW # and Team

 ­­­­­__x___100 Corn and Soybean Production and Protection
­­­­­_____ 110 Dairy
­­­­­_____ 120 Farm and Business Management
­­­­­_____ 130 Horticulture: Commercial and Consumer
­­­­­_____ 140 Iowa Beef Center
­­­­­_____ 150 Iowa Pork Industry Center
­­­­­_____ 160 Natural Resources and Stewardship

ANR Priority (select all that apply)

­­­­­_____Global Food Security and Hunger
­­­­­_____Regional Food Systems
­­­­­__x___Natural Resources & Environmental Stewardship
­­­­­_____Food Safety
­­­­­_____Sustainable Energy – Biofuels & Biobased Products
­­­­­_____Climate Change

Title of Success Story

Internet-based nitrogen rate guidelines for corn production

Continuing Story

__x___ No                _____  Yes (If continuing, what story?)

Knowledge Areas: (USDA categories)


Desired Changes

Learning, Actions

(Why is it important to address this issue with education?  What are the desired changes?)

Coordination of nutrient management recommendations on a multi-state basis is important due to the ease of information access today through the internet by a widely geographically dispersed audience and with increasing government programs across state boundaries. Providing current research-based information on nitrogen fertilization rate for corn production helps producers make input decisions and economically reach crop production goals. Use of the internet to locate production information has become commonplace for producers, crop advisers, and agency personnel. Providing information in on-line web tools allows for a consistent resource, and provides an avenue to update recommendations on an on-going basis instead of static guidelines.

The goal is to provide access to nitrogen rate guidelines for corn production via the interactive on-line calculator tool (Corn Nitrogen Rate Calculator) that is based on the regional guideline approach (Concepts and Rationale for Regional Rate Guidelines for Corn) and to provide yearly updates to the calculator with new user information, nitrogen response databases, and economic analysis.

(Outputs: activities, numbers reached, publications, products)

The on-line Corn Nitrogen Rate Calculator database was updated with new nitrogen rate trial research data, state information was added, and within-state specific user option selections were increased. The tool now has nitrogen recommendations for seven states across the Corn Belt (Iowa, Illinois, Indiana, Michigan, Minnesota, Ohio, and Wisconsin), and within state geographic option selections for three states. Information can be entered by the user to tailor the calculated rate to specific situations, such as state, state geographic area, soil yield potential, crop rotation, corn price, and nitrogen price. This regional approach allows uniformity of nitrogen rate development, but tailors the rate recommendations to specific state situations. The updating keeps the site current with new information and provides guidelines using the latest research available.

RESULTS (Outcomes:  specific changes that occurred in Learning, Actions, Conditions; how outcomes were measured)

Application of nitrogen is a major expense for corn production, and typically the largest production input cost. Economic payback from any input is essential to maintain economic viability of crop production. For nitrogen, there is also the potential of nitrate loss to water systems when more than recommended rates are used. Having a source of recent research information for producers and crop advisers is essential to making appropriate nitrogen rate decisions. The web based calculator tool is widely used, with many individuals using the information to guide nitrogen applications at a time when fertilizer costs and corn prices are fluctuating rapidly and are at record levels. In the past two years, there have been more than 29,000 visits and 160,000 page views to the corn nitrogen rate calculator web tool.

Public Value (now or future)
(Impact:  Who benefits beyond participants and how?  What conditions changed?)

This on-line calculator and timely information has helped producers maintain optimal nitrogen inputs and viable economic return from corn production. In addition, society benefits from reduced nitrate reaching water systems as optimal nitrogen rates are utilized by producers for corn production.

Major Partners or Collaborators

University Extension soil fertility and corn extension specialists:  Emerson Nafziger, University of Illinois; Jim Camberato, Purdue University; Kurt Steinke, Michigan State University; John Lamb, University of Minnesota; Robert Mullen, Ohio State University; Carrie Laboski, University of Wisconsin

Where story took place
(Region, campus, multi-regional)


Fiscal Year


Multi-state or Integrated (Ext + Research)


Funding Source



Nitrogen, Application Rate, Corn


Page last updated: July 1, 2011
Page maintained by Julie Honeick,