March 20, 2013

Name of App: Corn N Rate Calculator (Wisconsin)
Developer: University of Wisconsin
Availability: iPad, iPhone; Android
Cost: Free

Intended Audience: Farmers, agronomists, consultants in Wisconsin

Purpose of App: To assist producers in selecting a nitrogen rate that improves profitability when N and corn prices fluctuate.

Description: The app uses information from the University of Wisconsin publication, Nutrient Application Guidelines for Field, Vegetable, and Fruit Crops in Wisconsin (A2809). The recommendations are for Wisconsin and are based on their research on optimum N rates. These are adjusted for several factors: corn price, N price/lb, soil texture, and irrigation. The N rate recommended is further reduced for legume credits. One interesting feature is that all of the N recommended ranges produce a profit +/- $1/acre.

Fit for Nebraska: The UNL recommendation procedure for Nebraska takes into account soil nitrates, yield goal, irrigation nitrates, organic matter, and previous crop. After the N rate is determined, it is adjusted for economic factors and N application timing. This requires more information than the Wisconsin system. It would only be by chance that their recommendation would be similar to ours, especially when there are a lot of nitrogen credits. The part of the calculator that determines the cost per pound of N and the corn:nitrogen price ratio may be useful to anyone. (UNL Extension Recommendations are available in Fertilizer Suggestions for Corn, EC117, and the UNL Corn Nitrogen Recommendations Calculator, an Excel spreadsheet you can download and customize.

App Reviewer: Charles Shapiro, Professor of Agronomy and Horticulture, UNL.