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Alfalfa scissors cut sampling procedure

Alfalfa scissors cut sampling procedure

To estimate the pre-harvest quality of alfalfa, producers can use the scissors cut method. This involves regularly collecting alfalfa clippings from the field, and analyzing the samples.

How it works

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Interpreting scissors cut results

We recommend the following four steps when using scissors cut data to plan harvest schedules:

1. Set harvesting goals.

Match forage quality to animal needs. We recommend that alfalfa/grass forage quality be 150 RFV for milking dairy herds and 120 to 130 RFV for heifers, stocker cattle and lactating beef cattle. Red clover should be about 10 points higher in RFV.

Ration goals may vary, depending on other ration ingredients, herd production goals and other factors. Discuss ration goals with a nutrition advisor.

2. Adjust for field losses.

Under the best conditions, you’ll lose 15 percent (points) of the dry matter during harvesting.

This is why you should cut a field at 165 to 170 RFV, so end up with harvested forage of 150 RFV. Individual farm experience is an important consideration.

3. Adjust for total harvesting time.

Begin harvest even earlier to average 150 RFV for all fields. Research from the University of Wisconsin has shown that alfalfa’s RFV will decrease at a rate of 4 to 5 units per day during the late vegetative and flowering stages. Take this forage quality change into consideration when planning the first cutting.

For example, if it takes two weeks to harvest first cutting and we want to average 150 RFV, begin harvesting one week before RFV 170, as described previously. Seven days multiplied by a 4 or 5 RFV change per day equals 28 to 35 points RFV. This farm should begin harvesting when the scissors cut results indicate standing forage quality is 198 to 205 (170 plus 28 and 170 plus 35).

4. Adjust for local field conditions.

Scissors cut results generally are for alfalfa forage quality, though some councils are doing other forages such as small grains or clover. This means 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. If you’ve planted some of the newer, high-quality varieties, these should reach the desired forage quality two to three days later than standard varieties.

Acknowledgements

This webpage was adapted from information provided by Dan Undersander, Extension agronomist, University of Wisconsin, for the Wisconsin Forage Council in 1999.

Reviewed in 2018

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