Potential yield increase = 5-19%

“Crop rotation is low-hanging fruit growers should take advantage of,”says Coulter. Rotation boosts corn and soybean yields and cuts nitrogen (N) fertilizer requirements for corn. Field trials in Indiana and Wisconsin have shown corn yields in a soybean-corn rotation were 9% higher than those with continuous corn.

In central Illinois, the yield advantage for crop rotation is increasing, says Bassett, the Pioneer agronomist. “Continuous corn has had more issues in the last five years across a larger region. Growers have struggled to overcome the factors that drag down continuous corn yields,”such as nitrogen (N) tie-up, residue management, and disease and insect pressures.

In addition to lifting yields, rotation can help you:

Manage corn rootworms. The Rahns rotate corn and soybeans on most of their 7,000-acre operation. That helps keep corn rootworms and other pests under control, Rahn says. “We’d rather use rotation than soil-applied insecticides to manage rootworm.”

Only about 10% of the Rahns’acreage is continuous corn, mainly on high-pH ground that can handicap soybeans. For growers raising more corn than beans, Coulter advises a three-year rotation of corn-corn-soybeans. “There’s less of a yield penalty on second-year corn, plus higher soybean yields than normal.”

Improve soil productivity. Bassett works with a few Illinois growers who have recently added a third crop, wheat, to their rotation “to improve farm condition,”restore soil tilth and reduce corn residue buildup and compaction. Use of cover crops to correct compaction is garnering interest, too, she adds.

The Rahns grow about 200 acres of alfalfa. “The number one reason is for the health of the soil. Alfalfa breaks up compaction and disrupts weeds and pests. This is something our forefathers understood, and we’re starting to hear more about this.”The Rahns are targeting former continuous corn fields that have developed a compaction layer 12-18 in. down, due to manure tanker traffic. “We can’t get down that deep with tillage.”

They work with a young, local farmer, Scott Veenker, who seeds the crop in early spring and manages it. In the establishment year, they get two cuttings, followed by four cuttings in the second, third and fourth years. In the late fall of the fourth year, the stand is terminated with 2,4-D and glyphosate, then moldboard plowed.

In addition to improving soil quality, returns on alfalfa have outpaced soybeans, Rahn says, and “are close to returns on some corn fields.”Alfalfa also generates substantial N savings in the following corn crops. The Rahns take a 50% N credit for first-year corn after alfalfa, and a 25% credit for second-year corn. They also see yield boosts of 20% for corn following four years of alfalfa, and 10% for soybeans.