Growing Corn - Your Questions Answered

Resource: Dr. Fred Below, University of Illinois

Corn is king on many farms and because of that, it is often the crop that we get the most questions about. Below are some common questions and answers to help you grow your favourite crop.

What management factor that you control has the biggest impact on yield? 

Answer: Fertility

The most important nutrients that you need to feed to your corn crop are: Nitrogen / Phosphorus / Potassium / Sulfur / Zinc / Boron. Placement of these nutrients is key for corn because corn roots expand only 6-8 inches horizontally - roots do not cross the row.

Mobile nutrients including Nitrogen and Sulfur move vertically in the soil, so best placement of N / S is within the 6 inch root zone. Dr. Below’s research shows a 10 bu yield advantage for Y-Drop applied Nitrogen vs mid-row coulter application. The rest of the nutrients are immobile in the soil, so placement is even more important. P / K / Zn / B should be applied using in-furrow, banding, or dry-drop tools.

What is the next major innovation in corn hybrid technology?

Answer: SMART corn - shorter statured corn that has a number of environmental, management, and physiological advantages compared to conventional tall corn. Environmental advantage of short corn is that due to it’s thicker stalk it can withstand more wind. From a management perspective the benefit of short corn is that you can more easily get into the field later in the season for fungicide and fertility applications. The

biggest advantage is the physiology of short corn. Due to the stacked internodes below the corn ear, less plant energy goes to the stalk and that extra energy all goes to reproductive potential.

What management factor has changed the most in the last 50 years and needs to continue to change for high corn yields?

Answer: Plant Population Corn yield = (plants/acre) x (kernals/plant) x (weight/kernal)

You must increase at least one of these components to increase corn yield. Problem is that you can’t increase all because they are negatively related. As a grower you have most control over plants/acre. The challenge with increasing plant population is that each plant’s root system gets smaller. There is a 2.5% decrease in root mass per 1000 plant increase in

population. The solution is narrow rows. Dr. Below believes 38000 is the maximum population for 30-inch rows. Therefore the future of corn has to be narrow rows with higher population. Another advantage of narrow rows is that they intercept more light and sunlight is the energy that the plants use to produce yield.