No. 25 Article 4/December 9, 2011

Fertility Calculators Available for Android Devices

Two Android "apps" (computer programs for mobile devices) are now available to help answer common fertility questions.

The first app brings an Illinois-specific version of the multistate Corn Nitrogen Rate Calculator website to your Android smartphone or tablet. A few years ago the University of Illinois started recommending that farmers use the maximum return to nitrogen (MRTN) model for calculating the economic optimum nitrogen rate. Several Corn Belt states collaborated on developing this system and created a common website. The same data and formulas have been used to create the mobile calculator. You specify field location and rotation, as well as fertilizer and crop prices, and a customized optimum nitrogen rate is calculated. Just like the online version, the app provides a range of rates representing the top of the nitrogen return curve.

"How much P and K did my crop remove?" This question has probably sold a lot of copies of the Illinois Agronomy Handbook. In the current (24th) edition, the answer is on page 102 (Table 8.6, Maintenance fertilizer required for various crops). If you don't always have your handbook nearby but you have an Android device, this second app may be a good tool for you. It will do the calculations and even convert to pounds of DAP and 0-0-60. If you are on a 2-year replacement cycle, there is a special screen where you can enter crops and yields for both years and calculate a 2-year replacement amount.

Both apps are free from University of Illinois Extension and the Department of Crop Sciences. Emerson Nafziger and Fabián Fernández provided the background data and information that form the foundation for the calculators. If you would like to try one out, send me an e-mail ( with either "Send MRTN" or "Send PK" in the subject line.--Dennis Bowman

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