2008 GREEN COUNTY ALFALFA PEAQ DATA

Interpreting PEAQ Readings

First cutting alfalfa is the single most important cutting to farmers because it is 40% of the total season yield and is generally harvested for the milking dairy herd. Yet this is the cutting when forage quality is changing the fastest and is the one that generally has the lowest average forage quality. Because of the importance of this cutting and its generally low forage quality, local forage councils across the state have been doing scissors clipping and reporting forage quality to encourage more timely harvesting. These twice weekly readings of standing alfalfa have done much to encourage earlier harvesting of first cutting.

The question always asked is how to use the results. The results are valuable and with the appropriate use can help plan for harvesting of high quality forage. We recommend the following for steps when using scissors clip data to plan harvest schedules:

1. Set harvesting goals. Forage quality should be matched to animal needs because higher forage quality than the animals can use results in extra production expense with no return. We recommend forage quality 140-150 RFV for milking dairy herds and 120-130 for heifers, stocker cattle, and lactating beef cattle.
   
2. Make adjustments for field losses. Under the best of conditions 15% of the dry matter will be lost during harvesting. These losses occur from respiration and leaf loss. Thus forage quality can be expected to decline 10% from standing forage to stored forage under the best of conditions. Losses will be greater is conditions are less than optimal. Therefore it is necessary to cut a field at 165 to 170 RFV to end up with harvested forage of 150 RFV.
   
3. Make adjustment for total harvesting time. Step two will result in high quality forage from the harvested field but, where several fields are concerned, we have to begin even earlier to average 150 RFV for all fields. There is variability in rate of spring quality change with location and year, but for planning purposes we can use the average first cutting forage quality rate of change of 3 to 4 RFV per day. Thus, if it takes us two weeks to harvest first cutting and we want to average 150 RFV, we must begin harvesting one week before RFV 170 (from 2). Seven days times 3 or 4 RFV change per day equals 21 to 28 points RFV. Harvesting for this farm should begin when results indicate standing forage quality is 191 to 198 (170 plus 21 or 28).
   
4. Make adjustments for local Field conditions. The PEAQ results are generally for alfalfa forage quality (though some councils are doing other forages such as small grains or clover). This means that grassy fields will reach the stated forage quality earlier than pure alfalfa. Stands on lighter soils will tend to begin growing earlier and mature faster unless conditions are droughty. South slopes will also mature earlier than north slopes. Further, if you have planted some of the newer, high quality varieties, these should reach the desired forage quality two to three days later than standard varieties.

Please contact Mark Mayer for historical information or questions. Email: mark.mayer@ces.uwex.edu

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