NEWS for North Dakotans
Agriculture Communication, North Dakota State University
7 Morrill Hall, Fargo, ND 58105-5665

June 6, 1999

Measuring Stick Helps Alfalfa Producers Gauge Harvest Timing

The results from university research conducted during the past 30 years have produced several changes in recommendations regarding when to cut the season's first crop of alfalfa—from 10-percent bloom in 1970s to late-bud stage in the 1980s and now earlier still. Yet despite all that researched-based information, decisions about when to cut alfalfa to ensure the highest possible quality remain difficult ones for many producers to make, says an agronomist at North Dakota State University.

Now there's a low-tech tool based on the latest research data that producers can use to get a quick and reliable answer to the nagging question of when to cut hay. It's a simple measuring stick similar to those handed out freely at farm shows. In fact, the alfalfa stick is free too.

"I call it the RFV stick because producers can use it to estimate the relative feed value of their alfalfa," says Dwain Meyer, a professor in NDSU's Department of Plant Sciences.

The square stick, the length of a common yardstick, is being offered to producers for free by W-L Research, Inc., a seed company in Bakersfield, Calif. On three sides of the stick are RFV points that correlate with the vegetative, bud and bloom stages of alfalfa development.

The correlations on the measuring stick are based on the Predictive Equation for Alfalfa Quality (PEAQ), a system developed in the early 1990s by agronomists with the USDA's Agricultural Research Service working at the University of Wisconsin-Madison. Subsequent research has found that the system is accurate beyond the Wisconsin region and can actually provide reliable estimates for alfalfa producers across the nation.

Based on the PEAQ system, alfalfa is in the vegetative stage when plants are more than 12 inches tall but have no visible buds or flowers. In the early bud stage, alfalfa plants will have one or two nodes with visible buds, but no flowers or seed pods will be present. In the late bud stage, plants will have more than two nodes with visible buds but no open flowers or seed pods. Alfalfa plants in the early flower stage will have at least one node with one open flower. The late flower stage is characterized by plants having two or more nodes with open flowers.

The measuring stick provides accurate readings only in alfalfa fields where plants are at least 16 inches tall. Meyer says producers will need to take samples from four or five 2-square-foot areas per 40 acres. To use the stick, producers need to select both the most mature stem and the tallest stem (not the highest leaf) from each 2-square-foot area. Plant maturity indicates which side of the stick to use (vegetative, bud or bloom), with plant height determining RFV. For example, if the most mature stem in a sample area is in the early bud stage and the tallest stem is 28 inches high, the stick, calibrated to the PEAQ formula, indicates the alfalfa in the field should have an RFV of about 170.

"Producers have got to start harvesting when the RFV of alfalfa standing in the field is 175 or greater if they're shooting for an RFV of 150 in the bale," Meyer says. "Because whatever the relative feed value of alfalfa standing in the field, it will be less in the bale due to harvest loss. The average producer will lose about 25 to 35 units of RFV in the harvesting process."

Meyer will conduct additional tests this summer to verify how well the PEAQ formula and the measuring stick perform based on North Dakota's growing conditions.

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Source: Dwain Meyer (701) 231-8154

Editor: Dean Hulse (701) 231-6136