Photo credit: paul bica / Foter / CC BY
Nitrogen is vital to crop growth and understanding when corn plants use nitrogen can help growers apply nitrogen more efficiently.
As soon as nitrogen hits the soil, it begins to nitrify and is subject to loss. This would have many growers waiting to apply just before sow or even post-emergence. From emergence to V6, corn-after-soybeans takes up only about ten percent of available nitrogen. The remaining ninety percent is subject to loss for the first 90 days of the crop's life.
Rapid growth signals rapid N uptake -- V8 is when corn is most thirsty for nitrogen and when coupled with a small spring application, a V8 sidedress has been shown to dramatically increase yields and profit.
If possible, the window can even be stretched into V10 with a high-clearence tractor. Recent studies conducted at the Central Illinois Practical Farm Research site show that refreshing nitrogen just before corn hits its major growth spurt can have a great impact. Using a split-nitrogen application (UAN28), with a pre-emergence application coupled with a V10 sidedress, yields increased by an average of 12 bushels/acre and had higher net profit to the tune of $70.80/acre over the control group. The V10 sidedress application also outperformed sidedress at V5 by 2.8 bushels per acre.
The trick with nitrogen application is only doling out as much as your crop needs, and only when it needs it. A little just prior to emergence followed by a V5 or even a V10 application -- if you've got the gear -- can boost your corn yields by eliminating waste to nitrification, and save you money.