Alfalfa’s annual yield is the single most important factor determining its profit, because inputs, including harvesting costs, change little as yield increases, points out Phil Kaatz, Michigan State University Extension forage educator.

“The relationship is so strong that farmers should do all they can to remain in the high yield range with their alfalfa,” says Kaatz.

One of the challenges to alfalfa profitability is declining yield with stand age, says Kaatz. The decline is due to environmental stresses, wheel traffic and diseases. Crown rot, caused by a complex of up to four types of fungi – Rhizoctonia, Stagnospora, Colletotrichum and Fusarium – is one of the main culprits.

“Plant death due to crown rot is often blamed on winterkill, but several studies have revealed greater stand loss in the growing season,” he says.

On average in the Midwest, alfalfa stands yield 2-3% better in the second production year than the first. But yield declines 17-25% in the third production year and 34% in the fourth. As yield declines with advancing stand age, growers should consider replacing alfalfa stands to stay in a high yield range, says Kaatz.

“The economic value of the hay crop you harvest vs. the added production you may realize in a corn crop should be analyzed for your particular operation,” he adds. “Farmers should consider that, in a rotation with corn following alfalfa, corn will yield 10-15% higher and may have adequate nitrogen (other than starter), or about 150 lbs N, for the total corn crop when compared to a corn-following-corn rotation.”