Corn is using 4 to 8 pounds of nitrogen per day in the rapid growth stage. Many fields are there now. They are not quite tasseled. Some are even smaller, still knee-high to waist high. By the time corn tassels it will have utilized about 60% of the total nitrogen it will use for the entire season.
Brian Downing, agronomist for Stewart Seeds, thinks it's important to review how much N corn needs right now because where areas were drenched in late June with rain, the potential for running short of nitrogen is a real possibility. It can be the number one limiting factor on yield potential.
Denitrifcation and leaching account for most losses of N in saturated soils, he says. Denitrification happens when soils lose oxygen. That happens when water fills the pores where oxygen should be, because the water has nowhere to go. The N that is lost in this manner is in the nitrate form.
Even if you applied anhydrous ammonia with N-Serve, a University of Kentucky study says that six weeks after application you can lose 50% of the N under the right, or in this case, wrong, conditions. If you didn't use N-serve or an nitrogen stabilizer, you can lose 65%. Losses are even higher for other forms of N that may have been applied.
Who will need to make rescue treatments, perhaps with high-clearance sprayers with drops? It's hard to say, Denning says, but especially fields on light-colored soils with lower organic matter will be candidates. The wetter parts of fields will be candidates too. Once it dries out if plants and ears don't green back up, you may want to get serious about considering a rescue application of N on those fields. You might talk to a dealer now and have your plans in order just in case.