Two-rate nitrogen trial

By Greg LaBarge, CCA, Ohio State University Extension

Ohio’s corn nitrogen recommendation tool is the Corn Nitrogen Rate Calculator (https://www.cornnratecalc.org/). The Ohio database has over 300 trials where four or more rates were applied to understand nitrogen response over various soils, hybrids, and weather conditions. However, questions still exist on how the Maximum Return to Nitrogen (MRTN) rate affects yield and profitability on individual farms. Therefore, we propose a simple two-rate trial that compares the MRTN rate to a rate 50 pounds higher to check the yield and profit performance of the MRTN tool. If you use a nitrogen rate higher than the MRTN rate, we encourage you to use that rate compared to the lower MRTN rate.

Study basics

• We recommend a minimum of two nitrogen rates replicated no less than three times. 
• The total N rate (MRTN and MRTN +50) should include all N applied regardless of source (liquid or dry) or timings (Preplant, at-plant, sidedress).

Note: MRTN rate with $6 corn and $0.75 N is 170 lbs. per acre, or with $1.00 N is 153 lbs. per acre in a soybean-corn rotation.

• The farmer can select nitrogen sources, application methods, and timing that works in their system.
• You can find more information on this study at https://go.osu.edu/mrtnplus50

The University of Illinois shared results from a similar 2022 study earlier this year  https://go.osu.edu/tworatenillinois. This summary shows one way we can use the data. Having many sites with this two-rate study will provide us with regional data to identify where the MRTN rate is not working well. 

Contact your county Ag/NR educator or let me know at labarge.1@osu.edu or 740-956-5047 if you have questions or would like to participate.