NPK for Corn
Corn that has been adequately fertilized will dramatically outperform fields who have limiting factors of nutrient deficiencies. When choosing a corn fertilizer you should look carefully at not just the N-P-K listed in big print on the front label, but you should be able to read and understand the details on the smaller label.
Above is an example of a sample label.
Nitrogen Gets Most of The Focus
Nitrogen is broken up into the two forms of nitrogen that a plant can readily take up into the plant. Plants take up nutrients in the ionic form. Plants take nitrate and ammoniacal nitrogen up. Between the two, nitrate is the form of N that leads to more vegetative growth, but ammonium is for the roots of the plant and more useful for reproductive growth. Labels will also frequently break down the nitrogen listed on labels into water soluble organic N and water insoluble N.
How Much Nitrogen Does A Corn Plant Need?
If you’re trying to boost yields, a general rule of thumb is that it will take somewhere between .7 to a full lb of nitrogen in order to produce a bushel of corn. Some of that can be biological nitrogen, but generally speaking a portion of the plants needs will be made of up of either organic or inorganic inputs put into the field for the specific purpose of making up for the crop losses incurred by harvest.
Timing of Nitrogen Applications
While it can take as much as a pound of nitrogen for a bushel of corn, some studies and experimentation by growers in the field have found that the timing is critical for maximizing yields.
In the video below, David Hula, the world record breaking corn grower from Charles City, VA talks about the importance of timing his nitrogen applications in order to maximize his corn yields.
What Are The Other Nutrients A Corn Plant Needs?
Corn fertilizer frequently includes phosphorus, potassium and often sulfur to go along with nitrogen and possibly micronutrients. Mr. Hula feels the appropriate balance of nitrogen to sulfur is about 8 : 1.
Other nutrients will depend on deficiencies found either in the soil test, or in plant and tissue tests taken throughout the season.