Estimate Quality Of First Crop Alfalfa

Estimate Quality Of First Crop Alfalfa

Alfalfa growth and development is running about one week behind normal this spring. Farmers who usually consider making the cutting for first crop on May 25 need not be too concerned with not harvesting yet.

"With the next dry weather window we will see a lot of first crop forage harvested," says Brian Lang, Iowa State University Extension field agronomist at Decorah in northeast Iowa. "Predictive Equations of Alfalfa Quality or PEAQ monitoring is a method to use to help you decide when is the best time to make your first cutting of alfalfa for the season."

He adds, "This year the PEAQ method is showing alfalfa growth and development running about one week behind normal. Farmers who usually consider making their first cutting on May 25 or so need not be too concerned about not harvesting yet. Most of the alfalfa in Iowa is barely into bud stage this spring on May 25, 2011."   

PEAQ provides an estimate of the quality, measured as Relative Feed Value (RFV), of a crop of first-cutting alfalfa as the crop is standing in the field.

Use PEAQ method to estimate when you should make first cutting

Typically, the RFV of first crop alfalfa will decline 3 to 5 points per day as the crop matures. Under the best conditions, 10% to 20% of the forage dry matter will be lost at harvest. This amounts to approximately 15 RFV points for haylage and 25 RFV points for hay. Therefore, to end up with 150 RFV alfalfa, which is the minimum quality recommended for high producing lactating dairy cows, you should harvest the crop when PEAQ measurements predict a RFV of 165 to 175 for the standing forage. PEAQ reporting (click on "All Above Counties" on the lower right) shows less than half of the fields that are being monitored are ready for harvest (176 RFV or less) and the others are running 196 RFV or more are still one week or more away from harvest. 

"Farmers are welcome to follow the progress of these reports, but they are also encouraged to use PEAQ in their own fields to best determine when to take the first crop harvest of alfalfa," says Lang. "You should refer to ISU Extension's PEAQ fact sheet for guidelines on estimating the RFV of your alfalfa fields."  

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