Even though planting is delayed, alfalfa is growing and harvest is approaching. Alfalfa producers, consultants, and dealers can benefit from the Alfalfa Watch project, which helps predict optimum date for the first cutting by monitoring plant development and quality. Alfalfa plant growth and nutrient quality indicators are reported twice weekly at http://peaq.traill.uiuc.edu//

Alfalfa Watch estimates the preharvest quality in the field using the Predictive Equations for Alfalfa Quality (PEAQ) technique. PEAQ consists of predicting fiber and relative feed value (RFV) based upon the height of the tallest stem and stage of plant maturity within a sampling area. The method, developed at the University of Wisconsin, has been used in Illinois for many years and is a reliable guide for determining the optimum harvest date for first cutting.

At the PEAQ web site, you can calculate PEAQ, enter and track your own PEAQ values, and view PEAQ values by county and region in Illinois.

Since approximately 15 to 20 RFV units are lost during harvest, alfalfa needs to be cut at 165 to 170 RFV using PEAQ to have 150 RFV of harvested forage.

A change in RFV of 3 to 5 points per day in the standing forage has been noted, so adjustments need to be made for total harvesting time. This adjustment means that alfalfa may have to be harvested prior to 165 to 170 RFV as indicated by PEAQ.

As of May 7 in northern Illinois, fields being monitored using PEAQ averaged 17 inches tall and had a RFV of 229.

PEAQ is not designed to balance rations and it does not account for quality changes due to wilting, harvesting, and storage. The procedure is most accurate for good, healthy stands of pure alfalfa.

Many alfalfa seed companies have PEAQ measuring sticks that indicate the RFV of standing alfalfa based on the height and stage of maturity. A PEAQ stick is also available through the Illinois Forage and Grassland Council for $10 by writing IFGC, P.O. Box 233, Greenville, IL 62246, or by emailing Matt Bunger, mbunger@yahoo.com or Don Brown, Jr., don.brownjr@yahoo.com

Producers need to balance the PEAQ technique with short-term weather forecasts. Since maturity is the main factor affecting forage quality, timely harvest of alfalfa is the best strategy for obtaining high quality forage.