NITROGEN FOR CORN: TIMING, RATE, SOURCE, LOSS
2018
- Univ. of Missouri
Project Media
Nitrogen management for corn is complicated. Timing, rate, source, and
placement can all have significant impacts on success.
My research findings on N timing have been the most surprising to me. They
include:
• In the absence of excess rain, effects of N timing on corn grain yield are
rare. Even quite late applications can give full yield. This probably is not
true for silage corn.
• In the presence of excess rain, programs with all N applied before planting
usually perform poorly. In-season N is needed to produce full yield.
• I have never seen early N stress reduce ear row number enough to worry
about. In 2017, after 11 years of continuous no-till corn, the zero-N
treatment was 135 bushels behind the best treatment but only 0.3 rows
behind.
• Pre-plant N rarely matters. In 90 experiments comparing treatments with
and without pre-plant N, there were only 2 where the treatment without
preplant N lost yield. In both of these the first N was applied when the
corn was thigh-high.
• Nitrous oxide emissions were cut by 60% by using all-sidedress N
management.