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Hitting the field to plant corn? Mind these last-minute details

Farmers who have dodged recent rains and whose soil is warm enough are "kicking the tires and lighting the fires" in corn country. Spring planting time has arrived to the Corn Belt.

But, don't get too ahead of yourself without thinking about some key details before you head out to get the '09 crop in the ground, one specialist says.

"We are approaching the idea planting window for both corn and soybean and some planters are rolling now. The planting operation is one of the most important influences on final yield. Small mistakes made at planting time can haunt you the rest of the season," says Iowa State University (ISU) Extension field agronomist in Iowa City, Iowa, Jim Fawcett. "Many producers can get most of their corn planted in about three to four days, so starting a day too soon and planting half the corn under marginal conditions usually doesn't make sense."

Fawcett recommends keeping these points in mind when climbing into the tractor cab to start planting:

  • Don't plant into wet soils
    This can lead to sidewall compaction which can lead to season-long problems. The roots will have difficulty growing through the compacted zone made by the planter and will be pancaked into a flat plane in the direction of the planter. This can lead to uneven growth, rootless corn, and K deficiency symptoms due to poor root growth.
  • Don't plant too shallow
    When soil moisture is plentiful, producers are tempted to plant corn more shallow. For every corn field I see with problems caused by planting too deep, I see a hundred fields with problems caused by planting too shallow. If the seed ends up less than 1.5 inches deep, problems such as rootless corn and K deficiency symptoms are much more likely to occur. Even if the seed is placed 1.5 inches deep, sometimes the soil settles after planting or there is erosion so that the plant actually "sees" a more shallow depth. Corn should be planted 1.5 to 2 inches deep and error on the deep side.
  • Shoot for corn stands of about 30,000 to 34,000 plants per acre
    Seeding rates around 35,000 to 36,000 seeds per acre have given maximum net profits in recent trials. Ideal corn seeding rates have been increasing at a rate of about 400 seeds per acre per year. Average corn yields per plant haven’t changed much in the past 50 years. Most of the yield gain has been from breeding corn that can tolerate an increased population. If you are still planting the same population you did 10 years ago, you are paying 2009 seed prices and getting 1999 yields.
  • Pay attention to details at planting
    A little extra time making sure planter settings, seed spacing, depth, population, and soil conditions are correct can pay big dividends, especially with today's prices.

If you're starting this spring a step behind because weather prevented you from getting fertilizer applied last fall, you may be in a rush to get to planting. But, don't rush planting after anhydrous applications, Fawcett says. The time you need to wait depends on how and where you applied your NH3.

"There is no magic number of days to wait after applying anhydrous ammonia before it's safe to plant corn, but if the anhydrous is injected 7 or more inches deep with a good seal, the corn can usually be planted the same day with few problems," Fawcett says. "The anhydrous typically diffuses about 2.5 to 3 inches from the point of injection, resulting in a diffusion zone of 5 to 6 inches in diameter. If you inject the anhydrous 4 inches deep and plant 2 inches deep, you're planting into the zone and even waiting a week may not solve the problem."

Fertilizer costs have been the most high-profile input challenge for corn farmers in recent years. Prices have changed a great deal, and that's changed how some farmers are approaching their nitrogen application rates.

According to ISU's nitrogen rate calculator, Fawcett says the current average recommendation, assuming $4-per-bushel corn and $850-per-ton anhydrous prices, is around $116 pounds per acre. That's compared to a 123-pound-per-acre recommendation with $2 corn and $350 anhydrous.

"Although optimal N rates do go down somewhat as N prices go up, it's important to remember that we hopefully are no longer working with $2 corn," Fawcett says.

Farmers who have dodged recent rains and whose soil is warm enough are "kicking the tires and lighting the fires" in corn country. Spring planting time has arrived to the Corn Belt.

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