Corn growers wanting to ensure a healthy crop with strong yields need to plan ahead, including knowing when to plant, when and if to till, and how to make the right seed depth adjustments based on soil conditions, says an Ohio State University Extension expert.
"Mistakes made during crop establishment are usually irreversible, and can put a 'ceiling' on a crop's yield potential before the plants have even emerged," said agronomist Peter Thomison
Following are some proven practices that will help get a corn crop off to a good start:
Till only when necessary and under proper soil conditions. Avoid working wet soil, and reduce secondary tillage passes. Perform secondary tillage operations only when necessary to prepare an adequate seedbed. Shallow compaction created by excessive secondary tillage can reduce crop yields. Deep tillage should be used only when a compacted zone has been identified and soil is relatively dry. Late summer and fall are the best times for deep tillage.
Complete planting by early May. The recommended time for planting corn in northern Ohio is April 15 to May 10, and in southern Ohio April 10 to May 10. But if soil conditions are dry and soil temperatures are rising quickly, and the 5-7-day forecast calls for favorable conditions, start planting before the optimal date. During the 2-3 weeks of optimal corn planting time, there is, on average, about one out of three days for field work. This narrow window of opportunity further emphasizes the need to begin planting as soon as field conditions allow, even though the calendar date might be before the optimal date.
Avoid early planting on poorly drained soils or those prone to ponding. Yield reductions resulting from 'mudding the seed in' may be much greater than those resulting from a slight planting delay. Also, if dry corn seed absorbs cold water as a result of a cold rain or melting snow, 'imbibitional chilling injury' may result. Cold water can cause similar injury to seedling structures as they emerge during germination. Such injury in corn seed ruptures cell membranes and results in aborted radicles, proliferation of seminal roots and delayed seedling growth.
Adjust seeding depth according to soil conditions. Plant between 1.5 to 2 inches deep to provide for frost protection and adequate root development. In early to mid-April, when the soil is usually moist and evaporation rate is low, seed should be planted no deeper than 1.5 inches. When soils are warming up and drying fast in late May or early June, corn may be seeded more deeply, up to 2 to 2.5 inches on noncrusting soils. Consider seed-press wheels or seed firmers to ensure good seed-soil contact.
Adjust seed planting rates on field-by-field basis. Adjust planting rates by using the yield potential of a site as a major criterion for determining the appropriate plant population. Higher seeding rates are recommended for sites with high yield potential, high soil-fertility levels and water-holding capacity. Follow seed company recommendations to adjust plant population for specific hybrids.
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