Economic Benefit of Variable Rate Nitrogen Programs

Samuel Peterson

Split application of nitrogen has gained popularity with growers on corn acres as a way to potentially increase nitrogen efficiency, crop yields, net profit, as well as decreasing nitrogen loss. This typically means applying a portion of nitrogen pre-plant, followed by a seasonal application (top-dress) at the V4 to V7 growth stage. Recently, a number of VRN systems have been developed to further refine the rate of nitrogen applied during the top-dress application. The rate of top-dress nitrogen depends on a number of factors: yield history, soil type, environmental conditions prior to top-dress, satellite imagery and soil nitrate test levels.

The goal of this project is to compare the economic return, if any, of Variable Rate Nitrogen (VRN) programs to a flat rate recommendation. VRN programs typically cost an additional $5-10 per acre to implement over a flat rate recommendation so significant yield increase will need to be seen to justify the program. In this project, a 120 acre field of corn on corn with no manure history will be used to create strip trials comparing three VRN programs (Nitrate Now, Encirca, and R7) to a uniform flat rate. The strip trial will give each nitrogen program multiple replications over varying soil types to help collect the most accurate sample of data. The yield data collected will be used to help answer the question of which program is the most economical for the farmer.