Ideal fertility timing for top-notch hay


Hay crops can be tricky when it comes to agronomic considerations. Unlike annual crops, hay breaks dormancy, continues to grow and then mature after cutting, and eventually needs to rest up to go dormant again.

The unique characteristics of perennials means that fertility is needed at different times of year than most are used to, and, given the variability between, one-cut, two-cut, or more than three-cut stands, figuring out how to manage hay fields can be complicated.

Dan Undersander, professor emeritus of the University of Wisconsin, says that hay, and specifically alfalfa stands, do best with a two-pass fertility plan, in a three- to four-cut set up. Undersander prefers to fertilize after first and third cut (or last cut, depending) to at least replace the year’s removal of nutrients.

“Alfalfa removes 55 pounds of potash and five pounds of sulphur per ton,” he says, so some quick math will get you in the ballpark of removal. A split application with potassium decreases the likelihood of “luxury” consumption, he says. Fall fertility also means the stand overwinters better and has quick re-growth in the spring so you can avoid driving over that early spring growth.

Newer alfalfa varieties are faster to re-grow, Undersander says, which is good news, but it also means that moving bales off the field is more important that ever. “Recognize that every day after mowing that we drive over the field we lose 6% yield from next cutting. So three days is an 18% yield loss. Five days is 30% yield loss,” which explains why haylage and balage fields often yield more.

Hear more below from Dan Undersander on the July 9th Agronomy Monday episode of RealAg Radio! 

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