The Latest

Flint on Crops: Planting corn is a tough job – Commentary

Ernst Undesser
By Ernie Flint, Mississippi State University March 20, 2017

Flint on Crops: Planting corn is a tough job – Commentary

The first day of corn planting is difficult because it forces the grower to consider all the factors that influence this important part of the production system. Through the years I have listened as farmers go through the decision making process for that important first day of planting their crops.

 

Since corn is usually the first crop to be planted there is extra concern about getting it done right.

Many factors come together to influence the outcome of the corn planting operation. We have to control as many of them as possible because there are several that are controlled by the environment, specifically rainfall and temperature, along with the duration of any weather events that occur before, during, and after the planters roll.

My background in seed technology forces me to consider the seed first because the packaged living organism we place into the soil contains the entire plant in miniature. Close examination with a microscope will reveal the embryonic beginnings of stalk, roots, leaves, and the reproductive structures that will develop in seventy to eighty days following emergence.

The care with which the seed are placed into the soil is very important. Good conditions are essential for imbibition of water warm enough to support the process of respiration that converts stored energy into cell production and expansion.

This complex process produces the coleoptile, the specialized structure that pierces the soil above the seed and allows the first leaves to open in sunlight rather than below the soil surface where they would otherwise likely die. The first roots also emerge and begin the process of taking in water and nutrients from the soil.

Corn seed can tolerate fairly cool soil conditions, but the minimum recommended soil temperature of 50 degrees F is in my opinion cutting it close with regard to maintaining the rate of seedling development that produces good stands. I would prefer a soil temperature in the 60 to 65 F degree range to produce the uniform stand that will later influence yield so strongly.

The reality is that most growers plant when fields will support their equipment. Fortunately they usually succeed since corn seed are very tough when there is adequate moisture and oxygen that are needed for respiration.

Depth of placement is a big factor since too shallow will allow seed to dry out or for seedlings to fail in their effort to produce good roots. On the other hand, too deep may place the seed into saturated conditions where there is inadequate oxygen, leading to weak or dead seedlings.

Through the years we have come to believe that a depth of about 1.5 inches is minimal in most of the soils of this region while depths in excess of 2.5 inches may delay emergence and even reduce final stands.

The “happy medium” of around 1.75 to 2.25 inches is about right in my opinion. The deeper placement is more appropriate in no-tillage or “stale” soil conditions which are the most common today. In this case the coleoptile emerges through the slit created by the coulter(s) and crusting is seldom an issue.

Drainage is critical for emerging corn, or any other crop for that matter. Standing water is essentially a death sentence for seed of any crop. I prefer planting on beds, but in many cases this is not done these days. The alternative is to make certain that water flows off the field before it can puddle and force oxygen out of the soil.

Row spacing, even spacing down the row, and population are important issues, but vary a lot with the many factors which are tied to the diversity of production systems in use these days. Just remember that the seed you plant is alive and will do its best to produce plants for you, but it helps to make sure the conditions are as desirable as possible.

Thanks for your time.

Ernst Undesser
By Ernie Flint, Mississippi State University March 20, 2017