Early corn planting has benefits and downfalls
By Kylene Scott
When the temperature rises to 60 or maybe even 70 degrees during early spring, some farmers just might get the itch to test their luck and plant their corn crop a little early. Record corn prices may also play a role in some management decisions.
According to the U.S. Department of Agriculture, corn growers produced 10.8 billion bushels in 2012, 13 percent below the 2011 crop. The corn yield in 2012 is estimated at 123.4 bushels per acre, down from 147.2 yield in 2011. For these growers, the spring of 2012 looked like the beginning of a banner year, starting out with favorable conditions. Farmers planted at the fastest pace in U.S. history and planted the largest acreage in the past 75 years. But historic drought conditions in most of the corn-growing states caused the corn crop conditions to decline rapidly.
In Colorado, like many other areas where corn is grown, consideration should be given to available water, season length and other contributing factors that could help or hinder the corn crop.
For dryland corn, according to a Colorado State University planting guide, the optimum planting date is 10 to 14 days later than irrigated corn in Colorado. This time frame is usually around the second week of May. The reason for planting later is that water availability and not season length limits yield in dryland corn, and planting later may save soil water for later in the growing season.
Ron Meyer, Colorado State University Extension agronomist, said in northeast Colorado farmers wanting to plant early could have an early harvest with drier corn, but would have to deal with a late frost or even freeze.
"For eastern Colorado, we begin planting the fourth week in April," Meyer said. "A warm April would allow germination and emergence early, frost could burn back emerged corn. Our normal last spring frost date is the first week in May."
The planting window extends from late April to mid-May, and by planting later, the corn yield potential decreases.
"Weather has caused June plantings in the past with corresponding yields being reduced by 30 to 40 percent," Meyer said.
The CSU planting guide suggests planting slightly before the optimum planting date. This would result in early plant emergence and ground cover, increasing competitiveness against later emerging weeds. Early planted corn often has better stalk quality, resistance to pests but could also increase the chance of seed blights.
Plant corn by the calendar, not soil temperature, the guide stated. Soil temperatures can fluctuate markedly in springtime. If planting is delayed past the optimum date, yield potential is reduced and a farmer might want to consider reducing nitrogen, reducing seed rates and finding an earlier maturing hybrid.
With that in consideration, cold soils slow the germination of the corn seed, and emergence exposes seedlings to cold stress and disease pathogens reducing stands and yield. Adequate soil temperatures need to average 50 degrees at a depth of two inches.
"Lower soil temperatures cause emergence issues," Meyer said. "Soils can reach 50 degrees with warm April temps, then should a cold front move through, and even deposit light snow, soil temperatures cool quickly at two inches. If seed is in the ground during that event, emergence is slowed considerably, which exposes seedlings to further stress."
Also, it takes about seven days for corn seed to germinate and emerge under normal growing conditions. For farmers in eastern Colorado, planting the fourth week in April with a seven-day wait for emergence would mean corn seedlings are emerging the first week in May.
"If our average last frost day occurs the first week in May, corn is not damaged," Meyer said. "By the second week in May we have true leaves emerging from corn plants and frosts can damage those leaves."
However, Meyer explains, the growing point of corn does not emerge for some time after germination, which provides some protection for the plant. But frost damage could affect yield and delay harvest and crop drying time.
The longer germination and emergence takes, Meyer said, the greater the risk for seedling diseases and insect damage. The faster the corn seedlings emerge and begin growing, the risk factors are reduced for the above-mentioned production issues.
When having to irrigate for corn planting or germination, it is done early in the season and when the soils are extremely dry, as could be the case for this season Meyer predicts.
"If soil moisture is not adequate for germination, our producers will pre-plant irrigate then plant into moist soil," Meyer said. "Another strategy is to plant into dry soil and water the crop up."
Late spring frosts happen and the resulting severity depends on whether or not plants experience lethal cold temperatures--at or below 28 degrees--or simple frost--warmer than 28 degrees. Simple frost is often minor and limited to the death of the plants above the soil. Most of the growing point of a corn plant remains buried in the soil until the 5-leaf stage, according to the planting guide. The plants easily recover and suffer very little yield loss. It is, however, when the temperatures drop below 28 degrees or less for more than a few hours that the growing point region of a young corn plant can be injured or killed, even if it is still below the soil surface.
Early season frost damage hurts yields because of stand loss and not leaf damage. The CSU Planting Guide suggests waiting until the plants have recovered. Some corn leaves will darken and wither within a day after frost occurs. Give the plants three to five days after frost before assessing plant damage.
New leaf tissue will emerge from whorls on surviving corn plants, while dead plants will show no growth at all. Looking at the growing points will also help assess the damage. The plant will recover if the growing point is white and fleshy, but if it is mushy and discolored the plant is dead.
Hybrid genetics provide the basis for tolerance to cold stress, according to one seed company. High seed quality helps ensure that the seed will perform up to its genetic ability. Others focus on selecting the best genetics for consistent performance across a wide range of environments and producing high quality seed. But weather and soils often influence the stand establishment, even with excellent genetics and high seed quality. Many seed companies provide research-based advice that can help growers make informed decisions and better manage their field operations to maximize stands.
Kylene Scott can be reached by phone at 620-227-1804 or by email at firstname.lastname@example.org.