For this project, the total N rate was set at 180 pounds per acre, the Economically Optimal Nitrogen Rate (EONR) using a nitrogen to corn price ratio of 0.10. At planting, 40 pounds of N was applied in a 2 by 2 placement. The additional 140 pounds of nitrogen was applied to V4-V6 corn. The combination of nitrogen sources to meet the desired N rate was from MAP or DAP plus Urea, or 28% UAN depending on plot treatment to reach the total N need. The Urea product used was Environmentally Smart Nitrogen (ESN), a polymer-coated product to prevent against losses with surface applications. UAN 28% treatment was applied using a coulter injector. The dry fertilizer products were applied with a drop spreader.
Corn grain yields for 2020 and 2021 are shown in Table 1. No statistical differences were shown between the UAN 28% and DAP+Urea or MAP+Urea treatments in either year. The partial budget for the two-year fertilizer program may be advantageous for sidedress P even though nutrient sources have a higher per-unit N price. The calculation presented used fall 2021 fertilizer prices. The UAN 28% has an extra application trip with the fall P, plus the N from that fall application is lost.
Table 1. Corn yields and two-year fertilizer program cost using surface applied MAP and DAP at sidedress compared to coulter injected UAN 28%.
Sidedress Source | 2020 Yield (bu/A) | 2021 Yield (bu/A) | Two Year Fertilizer Program Cost @ Fall ‘21 prices |
UAN 28% | 148a | 206a | $ 285 |
DAP+Urea(ESN) | 151a | 202a | $ 248 |
MAP+Urea(ESN) | 146a | 200a | $ 268 |
LSD (0.1) | 6 | 8 | |
CV% | 3 | 3 | |
The point of this project was to start a conversation about different fertilizer application timing to increase fertilizer program efficiency. More equipment options are becoming available, making a dry fertilizer program possible. If you are in a liquid program, using 10-34-0 may be an option to consider.
Source : osu.edu