Six steps for growing continuous corn

“How many of you have been to a corn-on-corn presentation?” asked Paul Gaspar, an agronomy research scientist for Pioneer Hi-Bred International, to those attending a Pioneer Media Event this week.

Not surprisingly, a near-unanimous show of hands shot up.

He wasn’t through. “How many?” he asked.

Like farm media members, you’ve probably sat in on your share of continuous corn sessions on the farm meeting circuit this winter. With corn futures rocketing past the $4 per bushel mark this winter, it’s no wonder many of you are considering increasing corn planting.

Granted, you will take a yield hit of around 10% on corn-on-corn compared to corn rotated with soybeans. The good news is that after that first year of continuous corn, the yield decline levels off in subsequent years. And when you combine yield potential plus stratospheric prices, short-term economics point to continuous corn as a profitable option.

“People have been doing corn-on-corn in a lot of places,” says Alan Scott, a Pioneer northern market agronomy information manager based in Mankato, Minnesota. “It can be done, but it needs to be thought out. You need to do things before the seed goes in the ground. After the seed goes in the ground, there’s not a lot you can do.”

Some key steps include:

  • Select hybrids suited for corn-on-corn.As with rotated corn, yield potential still ranks as the top hybrid selection factor. However, it’s important to combine this with traits such as stand establishment, stalk quality, stress emergence and disease resistance. Producers who are considering planting more corn may find their selection narrowed, as many popular triple stack hybrids are sold out. However, hybrids well suited for continuous corn are still in supply, says Mike Hellmer, Pioneer agronomy information manager for the eastern market.
  • Manage residue.You’ll have to battle more residue with corn-on-corn. The increased residue can lower soil temperatures, leading to a cold environment for germination and emerging seedlings. It also can provide a haven for disease and insects.What to do? Plan on mounting residue managers on a planter that clear a zone for the seed 8 to 12 inches wide. It’’s also important to space seed uniformly. If possible, tillage can be used to bury stalks.  “In my part of the world, we’re seeing the moldboard plows come out again,” says Gaspar, who also is based in Mankato. University of Minnesota studies show a 15-bushel per acre yield increase with moldboard plowing over chisel plowing with continuous corn. That gap widens to nearly 35 bushels per acre when moldboard plowing is compared to no-till under continuous corn.
However, moldboard plowing also has soil erosion considerations and other negative impacts. In some areas, tillage like deep ripping may be more appropriate. Gasper points out that chopping stalks and spreading residue while combining are also important residue management steps.
  • Plant your best fields to corn-on-corn.
    Plant corn-on-corn hybrids on well-drained fields with high yield potential. These fields should also have medium textured soils with ample water-holding capacity and adequate nutrient levels.Be cautious when evaluating corn-on-corn data from around the country, adds Scott. Soil conditions can vary widely just within a few miles, and what works at one site may not work on your farm.

    “You have to know your own fields,” says Scott. “It’s fine to look at data around the country, but be aware there can be significant differences from your farm.”

  • Apply starter fertilizer.
    Stopping to fill planter starter boxes or tanks is a pain. But starter fertilizer can give seedlings the “oomph” they need to emerge from the cooler soils of continuous corn. Pop-up or starter is particularly encouraged on high pH or calcium carbonate soils.Starter fertilizer is just one component of fertility needs. Corn residue will tie up more nitrogen (N) than soybean residue as it decomposes. Thus, soil scientists suggest farmers boost N fertilizer rates by 30 to 50 pounds per acre above previous rates when switching from corn/soybeans to corn-after corn.

    Phosphorus (P) and potassium (K) are fairly similar for corn-on-corn-vs. corn after soybeans. Long-term, though, corn grain removes more P and less K from the soil. Banding P and K can improve nutrient uptake efficiencies, particularly on soils with pH above 7.2.

  • Plant into a good seedbed.
    A soggy and cold seedbed can be an ugly place for emerging seed. That’s why it’s important to avoid mudding in the seed. Wait until soils are fit to plant.You’ll need to give continuous corn fields more time to warm up than those rotated with soybeans. That’s why the Pioneer agronomists recommend planting corn fields following soybeans before planting those in continuous corn. It’s also important to select hybrids with strong stress emergence traits to withstand emergence stressors.
  • Manage insects and disease
    Continuous corn residue can be heaven on earth to a disease or insect. Fortunately, growers have numerous tools to manage these, such as transgenic hybrids resistant to corn rootworm. Seed treatments also can be applied to prevent seedling diseases and fend off secondary insects like wireworms.

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