Boosting corn yields doesn’t always result from doing just one thing right.
It’s often a combination of many key management decisions, with help from mother nature, that turns a good corn stand into a great corn stand.
Early planting is a well-known component of successful corn production, since environmental stress normally increases during the summer, reducing yield potential of late-planted corn.
However, rushing the process often instigates major problems that overwhelm the benefits of early planting. Most producers often hurry to get their crop planted because rainfall restricts days suitable for fieldwork during prime planting time.
Although corn is an amazingly productive plant, it will not tolerate problems at any growth stage without suffering some magnitude of yield reduction because of its determinate growth habit.
Soil temperature is the primary factor regulating germination rate. This can affect stand success and plant growth uniformity, both of which are paramount to high corn productivity.
Corn seed germination requires a minimal temperature of about 50 degrees and germination rate increases substantially as soil temperature rises.
Thus, the standard guideline for determining earliest planting date is when morning soil temperature at a 2‐inch soil depth is 55 degrees and/or 50 degrees at a 6 inch soil depth. These levels generally ensure emergence within two weeks.
Although early planting is a critical component of successful corn production, planting corn very early will not generally produce the highest yields Corn seed should normally be planted 1 ½ to 2.5 inches deep.
Planting depth should be set in the field during planting. This is important because soil texture, seedbed condition and soil moisture will influence optimal seeding depth.
Corn seed’s inherent energy and germination process ensure emergence from a 3 inch depth or more. However, the initiation point of the nodal root system (near the crown of the stem) is moved upward when corn seed is not planted deep enough or seedbeds settle substantially after planting.
Corn seed placed less than 1‐inch deep will develop nodal roots near or even above the soil surface. This potentially exposes these roots to factors such as hot, dry soil, herbicide injury, and insect predation which can significantly impede root development.
This often leads to standability problems, nutrient deficiencies and even drought stress throughout the year. Many corn growers use starter fertilizer to supplement their corn fertility program.
Starter fertilizer promotes earlier maturity, enhances plant vigor, and often improves grain yield, especially in minimum or no-tillage systems. Starter fertilizer works by providing a concentrated phosphorus supply directly in the root zone of young plants, which is particularly beneficial when soils are cold and wet. Phosphorus placement is very important to young plants with small root systems because phosphorus doesn’t move in the soil. Even though nitrogen is an important part of starter fertilizer, it can move in the soil. That’s why nitrogen placement is not as important to corn uptake, especially since corn has a fibrous root system with lots of lateral growth.
Thus, nitrogen fertilizers are not very valuable as starter fertilizers. Corn growers should generally strive for a goal of 28,000 to 35,000 plants per acre. Seeding rates should exceed the desired plant population about 5 to 10% depending upon planting conditions, seedbed preparation, and seed germination.
The optimum plant population may vary considerably from these guidelines, depending upon several factors. Dryland producers should moderate their goals, because they are dependent upon midseason rainfall to realize potential.
Early-maturing hybrids often have less leaf canopy than later hybrids, meaning they may be more responsive to higher seeding rates. Ultra-early planted corn (soil temperature 50-55) should be seeded about 10% thicker than normal because cool spring conditions usually promote higher seedling mortality and smaller plants with less leaf area at tassel, meaning more plants are needed to intercept available light.
Conversely, growers should reduce seeding rate at later planting dates since warm temperatures enhance seedling establishment and produce taller, leafier plants, but are more likely to expose the crop to late-season stress, decreasing grain yield potential.
A video on the best planting conditions for corn is at https://corn.ces.ncsu.edu/2021/04/what-are-the-optimal-planting-conditions-for-corn.