Using variable rate fertilizer application in no-till cornfields may save growers money, as well as potentially boost yields. Ohio State University researchers will educate attendees of the National No-Till Conference how to use the precision agriculture technology to minimize costs and maximize profits.
Randall Reeder, an OSU Extension agricultural engineer, and John Barker, an OSU Extension educator, will present "Getting a Solid Payback with Variable-Rate Fertilization" from 7:30 p.m. until 8:10 p.m. on Jan. 14. The 17th annual National No-Till Conference will be held Jan. 14-17 at The Westin in Indianapolis, Ind. For complete conference information, log on to www.lesspub.com/ntf/.

"The emphasis is to take advantage of current technology to make wise decisions on fertilizer application rates across a field," says Reeder.

Using variable rate application starts with developing a yield map based on data collected from yield monitors, which are standard now on most combines. The yield map identifies variations in a field. Based on soil types, yields and other known factors, farmers can divide the field into management zones and take soil samples in each zone. Then nutrient deficiencies can be corrected using variable rate applications of lime, nitrogen, phosphorus and/or potassium.

"Soil type, low fertility and pH levels are main factors in crop yields," says Reeder. "Farmers who have yield monitors and are not taking the extra step to use yield maps are missing a big opportunity to increase income. Applying nutrients only where needed, and at the proper rate, will save on fertilizer and lime costs and, at the same time, increase yields."

Ohio State researchers have shown, in field trials, that using variable rate applicators in no-till situations can save money, anywhere from $36 to more than $88 per acre, when compared to normal production practices and no precision agriculture use.

Barker, who conducted the study, will share the results with National No-Till attendees. The study was conducted on a 45-acre central Ohio farm using variable rate technology to manage fertilizer applications of potassium and phosphorus on three field scenarios: application based on soil test data with the field divided into 2.5 acre grids, application based on soil type, and application based on historical crop removal data using GIS software.

Results showed that overall fertilizer use (17,325 pounds for the 45-acre field) was the highest using the farmer's normal production practice of uniform application. By comparison, using grid soil sampling and variable rate applications, fertilizer use was reduced by 3,420 pounds. Using variable rate fertilization applications based on soil type and on historical crop removal data each reduced overall fertilizer use by more than 7,200 pounds for the 45-acre field.