Estimating yields on alfalfa or other hay crops can be challenging. Hay harvesting in the desert SW United States involves a period of curing and baling on dew moisture. Raking and Baling may occur at 3 am in the morning. We like to rise early here in the hot desert, but unless one sleeps in the field, one will miss the bale count. So here is our compromise to the traditional bale count to estimate yields on large research plots. We have used this method for a variety of trials ranging from fertility to soil amendments to soil micro-organism trials (seen here).
Here is a list of items needed: A field that had been cut. A pick up truck with an arm swung out off the bed of the truck. A milk scale. A tarp. Rakes. Measuring tape. Zip lock baggies. Clipboard. Pen. And a couple of assistants.
First measure a length of windrow in replicated plot with the tape.
The length of windrow is raked onto the tarp.
The tarp is weighed, the weight is recorded on the clipboard (don’t forget to post the tare weight).
A sub sample of the hay is placed into the zip lock bag. The bag is returned to the lab for dry matter test.
Yield is estimated by back calculating the net weight of the hay to tons/ac. Moisture content is then corrected by dividing the yield by the percent dry matter found from the lab analysis. Yields are commonly reported on Dry Matter or 90% dry matter basis.