Assessing pre‐plant nitrogen sources and waterlogging on corn growth and yield

Flooding and waterlogging from strong storms can negatively affect corn
(Zea mays L.) growth and yield. Ensuring adequate nitrogen (N) supply
after waterlogging is key to optimizing corn yield, though limited
evaluations of enhanced efficiency fertilizers have been conducted in
conjunction with waterlogging conditions. The objective was to quantify
how different pre‐plant incorporated N sources and post‐emergence
waterlogging affect corn N uptake, yield, and efficiency of applied N. A
split‐plot randomized complete block design was conducted in two locations
from 2021–2023. Waterlogging regimes (0 or 4 days) were implemented by
applying water at the V4–V6 growth stage. Pre‐plant incorporated N source
was the subplot factor consisting of a non‐fertilized control or 200 lbs N
acre−1 applied as urea (U; 46–0–0) or urea‐ammonium nitrate (UAN; 28–0–0)
alone or combined with either nitrapyrin or N‐(n‐butyl) thiophosphoric
triamide (NBPT), and polymer‐coated urea (PCU, 44–0–0). The optimum ear
leaf N concentration at R1 (2.75%–3.50%) was only achieved with U and PCU
when waterlogging occurred. Waterlogging reduced grain yield by 9% to 25%,
while N source (across waterlogging treatments) increased grain yield over
the non‐fertilized treatment by 14% to 45% or 236% to 343%, depending on
location. Grain yield was optimized with U, PCU, and U with nitrapyrin
regardless of waterlogging conditions. Dry fertilizer sources also
resulted in higher partial factor productivity compared to UAN treatments.
These results suggest that dry N sources of U, PCU, or U with nitrapyrin
should be considered in regions prone to waterlogging to optimize corn
grain yield.