Corn planting Soil temperature and moisture are critical

Published on April 4, 2020

With corn planting fast approaching, many growers often question when the optimum time to plant the crop is. According to Kansas State University (KSU) Crop Production Specialist Ignacio Ciampitti, corn planting should follow soil temperature and moisture rather than calendar dates. 

            During an episode of KSU’s Agriculture Today podcast, published March 24, Ciampitti discusses prime corn planting timing and the importance of corn seeding rates. 

Soil temperature

            Ciampitti says the ideal soil temperature for corn germination is between 55 to 60 degrees Fahrenheit. 

            “Corn emergence at 50 to 55 degrees Fahrenheit may take 18 to 21 days, while at 60 to 65 degrees Fahrenheit, corn emerges in eight to 10 days,” states Ciampitti. “Below 50 degrees Fahrenheit little, if any, germination can be expected.” 

Ciampitti explains some growers like to push the planting dates up to early April to get the full season corn through its tasseling and pollination stage before the dry summer heat. 

“There is some research to show this is an effective strategy, but there are some differences among varieties,” he says. 

He also points out, even if soil temperatures get up to 55 degrees on one warm day, germination won’t occur properly. The temperature needs to stay near 55 to 60 degrees for the duration of germination.

“If we take a look at the 10-day forecast, the weather this time of year usually fluctuates up and down a lot,” he notes. “Since corn is one of the most expensive seeds, we need to be very careful to make sure we do a good job planting, and soil temperature is a critical factor.” 

Ciampitti also notes good germination rate is directly correlated with yield.

“There has also been some recent research to show that later planted corn, as late as mid-June, can have comparable yields and sometimes even better yields,” Ciampitti continues. “However, this is dependent on the season and how the heat stress and rainfall patterns occurred with later planted corn when the spring was colder and mid-summer had favorable temperatures and rainfall.” 

Last spring freeze

            While discussing soil temperature, Ciampitti notes it is also important for growers to think about the last spring freeze and the impact of freeze damage on planted corn. 

            “If growers plant early, they might see effects of freeze,” Ciampitti states. 

            He then points out a tool KSU uses that shows the average dates for the last spring freeze, which he notes changes dramatically. 

            “Some years the last spring freeze may occur early in April, and some years it occurs mid-May,” he says. “If producers are planting now, there is a high probability they will be impacted by freeze.” 

Soil moisture

In addition to soil temperature, Ciampitti notes soil moisture also affects the timing of corn planting. 

“Adequate soil moisture is another critical factor for planting corn,” he says. “However, excess moisture might delay planting.” 

As far as moisture goes this year, Ciampitti says he believes the Midwest is in pretty good shape. 

Seeding rate

            Ciampitti also notes seeding rate is an important factor for corn planting.

            “The optimal corn seeding rate for any situation will depend on the anticipated environment and how the hybrid responds to the environment,” he says. 

            He notes some environmental factors such as soil type and fertility can be anticipated, while other factors such as rainfall remain unknown. 

            “If five percent of corn is barren at the end of the season, the planting rate was too high, while if there are more than 600 kernels per ear and the second ear is contributing to yield, the planting rate was too low,” he explains. 

            Hannah Bugas is the assistant editor for the Wyoming Livestock Roundup. Send comments on this article to roundup@wylr.net.