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What’s the Alfalfa Crop Doing?

Alfalfa Shoots

University of Minnesota Extension, Stearns County News
March 8, 2017         
Source:  Dan Martens, Extension Educator
University of Minnesota Extension
Stearns, Benton & Morrison Counties

What’s the Alfalfa Crop Doing?
By Dan Martens, University of Minnesota Extension

FOLEY, Minn. (03/08/17) — A farm store agronomist sent a picture by email on February 21 of some alfalfa shoots in a field near Albany. Thanks. Shoots with small leaves appear to be about an inch long or so. A couple years ago, after a January thaw, I shared a picture similar to this with Craig Shaeffer, U of M forage research faculty. He shared in that situation, even though the ground had thawed some, the soil likely was not warm enough for the alfalfa to actually grow. It was more likely those shoots were there late in the fall.

I’m not saying the same assessment applies here, but it’s a possibility. If you dug up a crown now, you might also see white sprouts or shoots that likely were there last fall and/or might start growing now if the soils warm up enough.

When I see these situations, I resolve to spend some time on my hands and knees in hay fields late into the fall, and then scratching through the snow every month through the winter, or at least taking a look if a winter thaw happens. But I usually get distracted with other things and don’t follow this very closely. So if you’re up to a learning adventure… or have 4H, FFA or science class students who need a project, it could be interesting to watch.

In some ways, it maybe doesn’t matter a lot whether these shoots were there late in the fall or have emerged now, other than noting if alfalfa breaks dormancy. If plants break dormancy, they tend to be less durable with any more significantly cold weather.

Sometimes buds or shoots that form in the fall are killed through winter, but the root and crown are healthy enough to start news bud. These fields or area of fields will likely start a bit slower. Patience can be an asset.

Sometimes as things thaw out, you can tell the root is getting soft and mushy before anything has had a chance to grow much at all. And sometimes roots look firm early, because they have been refrigerated in cold soil, and then deterioration and decay of winter damaged tissue sets in later. We sometimes need to wait until things warm up enough so alfalfa in that field or nearby has had a chance to get to be as much as 6 inches tall before we can be very confident about the field.

Alfalfa growers know there can be a lot of variation across fields, from field to field and farm to farm. We have some reason for concern. Alfalfa is usually more durable through the winter if it is a little on the dry side in the fall. On the other hand a longer fall season may have allowed plants to store more root reserve; and use less.

Ice sheets, especially without many stems sticking through, can smother alfalfa. Ice sheets can trap carbon dioxide given off through respiration by dormant plants, and restrict a fresh air exchange for oxygen. Small areas like this might be seeded to an annual grass that would provide some forage by second crop; and keep weeds in check.

The expansion and contraction of thawing and freezing soil can stretch and break roots. I’ve remember seeing crowns in one field several years ago that were left a couple of inches above the soil surface when things settled down in the spring.

I’m not quick to say there will be lots of problems this spring, and I’m not quick to say there won’t be any. It could be safe to say, more issues than an average year. Time will tell. As I’ve said before, farmers wisely learn to have plan A for many situations on the farm, along with a couple other options - ready to use, as they see how things unfold. Re-seeding extra acres is still expensive.

Where corn follows alfalfa, whether because of winter injury or normal rotation, be sure to check the new Corn Fertilizer guidelines for how nitrogen credits figure into nitrogen needs for the corn crop. Do an Internet search for “Minnesota Extension Nutrient Management”, give us a call, and/or ask your agronomy advisor to work with you based on this information.

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