NEWS for North Dakotans
Agriculture Communication, North Dakota State University
7 Morrill Hall, Fargo, ND 58105-5665
April 27, 2000
The latest research on alfalfa quality at North Dakota State University is showing that in wetter years, making harvest decisions based on plant height and plant maturity rather than on plant maturity alone may result in a consistently higher relative feed value (RFV) in the field--which translates into higher-quality alfalfa in the bale.
"In order to be considered prime hay, alfalfa in the bale must have an RFV of 151 or greater," explains Dwain Meyer, NDSU plant sciences professor. "The reason we shoot for an RFV of 175 to 180 in the field is because wilting, harvesting and storage can lower RFV by 25 to 30 points."
In trials during the past few years, Meyer has taken first cuttings on dryland plots at the late-bud stage and discovered that the alfalfa had an average RFV of 125 in the field, a value about 50 points lower than the in-field RFV goal. He attributes the lower quality to above-average rainfall, which has resulted in more robust early growth of alfalfa plants--in the form of taller plants.
"The taller the plant gets, the earlier you need to harvest," Meyer says. "A first harvest at the late-bud stage in wetter years, or under irrigation, will be too late."
Based on his data, Meyer says that alfalfa producers managing a three-cut system should consider taking the first harvest no later than the late-vegetative or early bud stage if the stem height of the tallest alfalfa plants is nearing 30 inches. But if the first alfalfa growth is much shorter, then producers should postpone their first harvest, probably until the late-bud stage.
"Generally, dryland alfalfa may reach only 15 to 20 inches and it is not uncommon for the third crop of irrigated alfalfa to reach only 20 inches in height," Meyer says. "So in these situations, harvest can occur at a later growth stage, probably the near the mid-flower stage, or about 20- to 50-percent bloom. At this stage, producers could still expect to harvest prime hay."
To determine plant height and maturity stage (preharvest alfalfa quality), producers should take samples from five representative 2-square-foot areas in fields of 30 acres or smaller and add one or two samples for every additional 10 acres in larger fields. Measure the height of the tallest stem, not the highest leaf. Meyer says the tallest stem may not be the most mature stem.
Meyer offers the following visual indicators for determining alfalfa maturity:
In summary, Meyer says, "Many producers take the first harvest too late to obtain quality hay in years with good moisture. Harvest should begin in the late-vegetative to very early bud stage. Conversely, several producers take the third harvest too early. Harvesting at the mid- to late-bloom growth stage can produce prime hay when the growth of the plant is less than 15 to 16 inches in height. In short, adjust the maturity stage at which harvest begins based on the height of the plant."
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Source: Dwain Meyer (701) 231-8154
Editor: Dean Hulse (701) 231-6136