John Agee is hard pressed when asked his secrets of continuous corn production. “What you do is really no different (than a corn-soybean rotation),you just have to watch over everything more closely,” he says.

Agee is perched in his black pickup to share his views while two combines lap around one of Agee Farms' numerous corn fields. Since the late 1990s, the operation has grown from about 2,500 acres to a dramatically larger scale, which Agee declines to pinpoint. The home base is in New Holland, IL, with farms scattered across seven counties in central Illinois.

“We never had a big plan to grow so big, it all just sort of snowballed,” says John, who farms with his son Justin and brother Jeff. They have help from eight full- and part-time employees, including several of the Agees' extended family members.

The Agee family planted 100% of their 2007 acres in corn, with about 85% of it corn-corn. They say their entire crop will likely be devoted to corn again in 2008. “The demand is so great right now we can't see doing anything differently at this time,” says John.

Growing corn year after year on the same ground comes with some performance risks. Researchers say corn growers can expect yields about 9% lower on the average for second-year corn vs. corn grown in rotation.

According to Purdue Extension corn specialist Bob Nielsen, much of the potential yield loss stems from heavy crop residue. Pound for pound, corn stalks and cobs left behind in a field equal the grain harvested. Heavy residue is difficult to navigate with planters and fertilizer applicators and it can interfere with springtime warming and drying of soils, potentially leading to slow germination, emergence and stand development.

Nielsen says growers also need to be aware of the impact high residue levels can have in carryover of diseases like gray leaf spot. In addition, heavy residues reduce the efficacy of soil-applied herbicides, and they can slowly modify soil environments to cause shifts in weed patterns.

“Growers who do a good job in managing residues are the ones facing less risk of yield losses in corn-on-corn,” Nielsen says.

The Purdue researchers warn growers to also be on the lookout for nitrogen (N) deficiencies in soil where corn is grown over multiple years. Some experts suggest growers need to add 30-50 lbs. more N per acre on corn-corn land versus corn grown with legume rotations. Farmers must also monitor other soil nutrients, especially potassium, which is important for maintaining strong healthy stalks.

The Agees are n't too worried about possible yield losses. As an example, Justin gestures to a field he recently combined that was half bean stubble and half corn residue when it was planted last spring. “Yield was almost exactly the same,” he states.

Here are five corn-corn tips from the Agee operation:

“We scout for everything that can happen in a field including weeds, insects and disease,” says John. This past summer the Agees found gray leaf spot in several fields, prompting them to aerially treat their entire crop with a fungicide.

In the fall, the Agees look for winter annuals, such as common chickweed and henbit, and treat the most heavily infested fields first. “We'll apply to that 30% and then spray other fields as weather permits,” says John.

The Agees haven't found a single magic bullet to ensure success with corn year after year. “It takes it all — the right hybrids, the right amount of fertilizer and good scouting — to make it work,” says Justin.

Editor's Note: For more on continuous corn management, see http://cornandsoybeandigestcom/cornoncorn/cid=microsites and www.agry.purdue.edu/ext/corn/news/articles.06/CornAfterCorn-1121.pdf.