COLUMBUS – Droughts, insects and diseases can take a bite out of corn yields, but missing the boat on crop establishment also may have a detrimental effect on the crop’s performance.
Peter Thomison, an Ohio State University Extension agronomist, said that such practices as proper tillage, paying attention to soil conditions and seeding at the right depths can make a big difference in yields at the end of the growing season.
“The sins of poor crop establishment will come back later on to haunt you,” said Thomison, an associate professor with the department of horticulture and crop science.
“Mistakes made during the planting operation are usually irreversible, and can put a ‘ceiling’ on the crop’s yield potential before the plants have even emerged.”
Can control. Although growers have little control over environmental conditions – the driving factor behind last year’s poor crop development – they can help send the corn off to a good start by following some basic planting rules of thumb.
Till only when necessary and avoid planting in wet soils or in no-till fields too early.
“Shallow compaction created by excessive tillage can reduce crop yields, especially under drought-stressed conditions like those that occurred in 2002,” said Thomison.
“Compaction can have a detrimental effect on corn emergence, causing poor nodal root development.
“Cloddy soils resulting from spring tillage of wet soils can cause the plant to leaf out underground. This is a mortal injury to the plant.”
He added that some growers tend to push no-till fields too hard, too early because the residue will support the equipment, even though fields may really be too wet to plant.
“I emphasize soil condition, because that was the root of so many problems growers had last year,” said Thomison.
“A good way to test the soil is to dig up soil samples in the field. The soil may be dry on the surface, but could still be too wet five or six inches deep.”
Finish on time. Complete planting by mid-May if weather permits.
Thomison said planting as early as possible under dry conditions can be advantageous for the crop.
“In addition to producing higher yields, early planted corn matures earlier in the fall with more time for field drying and higher test weights. Planting earlier can also mean earlier plant emergence and faster canopy closure during the growing season,” he said.
“Early planted corn usually has better stalk quality and may reduce the exposure to various late insect and disease pest problems.”
Optimize. Growers are recommended to plant half of their corn acres two weeks before the optimal planting date to optimize yield potential.
The longer growers wait to plant after the optimal planting dates, the more the yields tend to decrease.
Recommended planting dates for corn in southern Ohio is from April 10 to May 10 and in northern Ohio, from April 15 to May 10.
“If soil conditions are good and fields are dry and well-drained, then planting should proceed,” said Thomison.
Adjust. Adjust seeding depth according to field conditions.
“Irregular planting depths contribute to uneven plant emergence, which can reduce yields,” said Thomison.
Growers are recommended to seed between 1 1/2 to 2 inches deep, shallower when soils are moist and deeper when soils become more warm and dry.
Adjust seeding rates based on yield potential.
“Higher seeding rates are recommended for sites with high yield potential with high soil fertility and water-holding capacity,” said Thomison, adding that stands of 28,000 to 30,000 plants per acre or more may be required to produce yields of 160 bushels per acre or more.
“When planting occurs in cold soils, usually very early planting dates, the seeding rate should be 10 percent to 15 percent higher than the desired harvest population.”
In the case of a late planting after June 1 or on droughty soils, growers should lower their seeding rates.
“On soils that average 120 bushels per acre or less, final stands of 20,000 to 22,000 plants per acre may be adequate for optimal yields,” said Thomison.
