Tips for Your First Alfalfa Cutting

Much of the U.S. avoided severe winter weather, but winter alfalfa damage still can be quite variable from field to field. Some damage seen now may go back to your last fall cutting.

“A best management practice is to ensure your alfalfa crop has time to accumulate enough reserves to allow a lot of vigor in spring,” said Keith Johnson, agronomy professor and Extension forage specialist at Purdue University. “We need about five weeks of regrowth after the late-summer cutting before the first killing freeze hits. Now is the time to assess the crown and the taproot to determine crop health and to look for deterioration from disease organisms.”

Purdue alfalfa research indicates at least 35 exceptional stems per square foot are required for a viable stand and a high-yielding crop.

Dr. Keith Johnson, Purdue University Extension forage specialist, is evaluating alfalfa weevil damage and maturity stage before first harvest begins. Photo courtesy of Brooke Stefancik, Purdue agronomy graduate student

“In early spring, start looking for alfalfa weevil. A good scouting program is critically important to make sure pest damage hasn’t reached an economic threshold,” he said. “Watch for tip feeding and the percentage of stems that are defoliated to determine whether an insecticide application is needed.”

Maintaining proper soil fertility is critical for yield and persistence of the stand. Depleted levels of phosphorus or potassium can have a significant negative impact on productivity. Soil pH should not be lower than 6.6 for top yield. Soil testing is important so that the over- or under-applying of nutrients does not occur.

Time to Harvest

Don’t cut alfalfa too early, before floral bud development; give it time to accumulate enough reserves to grow an excellent crop for a second harvest. Harvesting too early and too often will reduce plant strength.

“Bloom can be a poor predictor of first-cutting harvest. Look at the base of the plant and if you can see crown buds of the second growth developing, then it's safe to harvest,” he said. “That’s the start of your second alfalfa crop. Bloom tends to be a good indicator from then on, but for the first harvest, I'd keep a watch at the ground level.”

Typically, mid-bud to late-bud stage is when dairy producers will harvest top-quality alfalfa. However, beef cattle producers can stretch into early flower. There may be a slight loss in quality, but yield will be higher.

When harvesting, lay the crop in a windrow to wilt to the desired moisture content. The length of time wilting requires depends on the temperature, humidity, solar radiation, wetness of the ground and wind speed.

To gauge the moisture level of alfalfa laid in a windrow, Johnson recommends going out to the field with your forage harvester, chopping a representative sample and collecting an amount in your hand. Squeeze your hand into a fist. If moisture oozes out of your hand, the forage is too wet to make into silage. If you squeeze and open and the ball has a slow release, then it’s close to an ideal moisture content. If you open your hand and that ball immediately falls apart, then the moisture content is too dry.

“Standing alfalfa will typically be at 75% to 80% moisture. We want the crop to wilt to a moisture level specific to the type of silo being used,” he said. “In bunker silos, we'd like to be at 60% to 70% moisture; alfalfa packaged in a round bale or large square bale and wrapped with plastic should be at 45% to 60%; chopped forage placed in a bag should be at 55% to 65%.”

Monitoring proper moisture level is critical to successful fermentation and lessens the opportunity for Clostridium bacteria in too-wet forage to produce butyric acid which can cause palatability and health issues for livestock.