What is in this article?:
N risk management advice in a nutshell:
- Time in-ground and wild, wet springs reduce N availability.
- Delay N applications on lighter soils until spring.
- Don’t count on one-time fall-applied or even early spring-applied N to be there when and where corn needs it.
- Get more efficient N use by piggybacking N application with other field trips—apply N in as many operations as you can.
- Sidedress as soon as you can.
- Save N adjustments until final sidedress, then apply according to soil tests.
- Don’t fall-apply N on high-pH soils.
Fall N application advice
The University of Missouri, like most who make N recommendations, says the BMP of timing for N fertilizer applications is to apply fertilizer as close as possible to the period of rapid crop uptake. Fall N application is considered relatively high risk and is not a BMP. For those who are willing to take the risk in order to apply N at a lower cost and without interfering with spring field work, the University of Missouri Extension recommends:
- Use only anhydrous ammonia—it converts to nitrate more slowly than any other form.
- Use a stabilizer.
- Apply N on no more than half—preferably only one-quarter—of planned corn acres to limit your risk.
- Delay application of anhydrous ammonia until the soil temperature at a 6-inch depth reaches 50 degrees
- The risk of N loss increases the farther south you farm in Missouri
- High-pH soils are more likely to lose fall-applied N, don’t fall-apply N on them.