When to make the first cutting of alfalfa and mixed alfalfa/grass hay sets the stage for the rest of the year.
Hay producers must answer a couple of questions when deciding the timing of the first spring cutting, says Steve Barnhart, Iowa State University Extension forage agronomist. What’s the hay harvesting schedule you desire? What are your objectives for the harvested hay crop or forage stand?
Harvest schedule decisions tend to be guided by what’s most important. Your objectives may include harvested yield, nutritive quality of the forage, or vigor and persistence of the perennial stand.
“Reaching a high level of all three objectives is unlikely with a single chosen harvest schedule,” says Barnhart. “Growers can generally meet two of the three with a chosen harvest schedule, but not all three. So, there are usually some compromises when harvesting.” He offers some observations to help you determine what kind of a hay or haylage cutting schedule you want to use.
What quality do you want?
Do you want high-quality hay at an acceptable yield level?
In general, more frequent harvests produce forage of higher nutritive quality at an acceptable yield level, but at a sacrifice in stand vigor or longevity. Conversely, less frequent harvest will produce acceptable yields and a greater degree of stand persistence and plant vigor, but the forage will have a lower nutritive value, notes Barnhart.
Maximum dry-matter yield of alfalfa and most forages is often obtained by harvesting the first cutting of the season at nearly full bloom and harvesting subsequent cuttings at 40- to 45-day intervals until late August or early September, referred to as a “3 summer-cut system.” This system produces forage relatively lower in nutritive quality.
Such forage is suitable for livestock on maintenance rations, or slower-weight-gain livestock enterprises, and can be used in low-performance feeding programs. To add additional harvested yield, growers who use a 3 summer-cut system will often harvest a fourth cutting in mid-to-late October.
Going for higher-value hay
High-performance livestock feeding programs require higher nutritive value forage. The optimal compromise for higher forage quality and dry-matter yield of alfalfa is to harvest the first cutting at late-bud to first-flower stage and make subsequent cuttings at 32- to 35-day intervals until late August or early September, often referred to as a “4 summer-cut system.”
Growers who are using a 4 summer-cut system will sometimes harvest a fifth cutting in late fall, also typically high nutritive quality forage. This latter 4 summer-cut system has led to a greater stand reduction and shortened stand longevity than those managed under a 3 summer-cut system.
The negative impact on stand vigor and longevity are usually made worse when a late-autumn cut is added to either the 4 summer-cut system as a fifth cutting, or to a 3 summer-cut system as a fourth cutting.
Alfalfa and alfalfa-dominant mixed legume/grass stands mature more quickly and lose nutritive quality faster during the first growth cycle of the spring than during summer growth cycles. “Growers desiring high-quality alfalfa hay at first cutting must manage the first seasonal cutting more closely to meet their particular forage quality goals,” notes Barnhart.
To complicate this management of forages even more, each spring growing season is a little different and may be a week or more different from one year to the next in the rate of crop development. Growers managing for high quality are encouraged to use one of the “heads up” methods for predicting the quality of a standing crop in the field.
Deciding when to cut
There are several ways to decide when to cut, if you know what relative feed value, or RFV, you need. You could go by the calendar and plan to cut at the same time you cut last year but with year-to-year variations in seasons, that’s really not a good system.
Another way is to look at the stage of development of the alfalfa, he explains. You need to understand how alfalfa grows. The first developmental stage is the vegetative stage when no buds have appeared. Forage quality at this stage is often too high for most livestock.
Next is the early- through late-bud stage. In early bud, you can’t see the bud yet, but you can feel it in the stem tips. In late bud, there’s a large, visible bud, just before open bloom. Then comes bloom stage, followed by the seed pod stage when nutritional value of the plant is decreasing rapidly with each day of harvest delay.
For high-performance animals, the first cutting should be made from early-to-mid bud, says Barnhart. For beef cows, late bud through midbloom is fine, and for dry, open ewes, the full bloom stage is acceptable.
In Iowa, alfalfa bud stages generally occur around mid-May when producers would typically make a first cutting for dairy cattle. But keep in mind spring may be a few days ahead or behind normal, so relying on last year’s first cutting date may not be appropriate this year.
Once a first cutting of alfalfa is made, bud stages on the regrowth generally occur again about every 30 days after cutting, allowing four bud stage, dairy quality cuttings per season. “Your most critical decision then is when to make that first cutting,” notes Barnhart.
Using either scissors clipping or the PEAQ method, another calculation must be made for anticipated harvest and storage losses that will occur. Generally, 10% to 15% harvest and storage losses are expected. So for each biweekly sample, about 10 to 20 RFV or RFQ units should be deducted from that of the standing crop.
How about forage grasses?
Forage grasses develop similarly to pure alfalfa stands. As forage grasses mature, yield at cutting increases and plant vigor and persistence improves, but feeding value declines. “For most forage grasses,” says Barnhart, “the first growth of spring also has a seed stem that both adds yield and reduces feeding value faster with advancing maturity.”
The cutting decision for “all grass” and grass-dominant mixed hay should be based on feed quality needs. Grass is considered higher in fiber than alfalfa, so alfalfa and alfalfa-dominant hay mixtures of less than 20% of the stand or hay composition is generally recommended for lactating dairy cattle.
For other classes of livestock, harvesting at seed head emergence or soon after is the most common harvest “target.” Waiting to harvest forage grasses that have matured into the seed formation stages generally does not add significantly to the yield, and produces lower and lower feeding value hay.