Welcome back! This is our first week of monitoring 1st cutting for quality in 2021. If you are not familiar with our procedures, we use alfalfa height to predict Neutral Detergent Fiber (NDF) for alfalfa, alfalfa/grass mixed and grass stands. Alfalfa height has proven to be a reliable indicator of NDF values in the field. Here are numbers that are helpful when using alfalfa and grass height as an indicator of NDF content. In general:

Begin cutting 100% grass stands when nearby alfalfa is 14" tall to achieve the desired 50% NDF.
Begin cutting 50/50 alfalfa/grass stands when nearby alfalfa is 22" tall for the desired 44% NDF.
Begin cutting 100% alfalfa stands when alfalfa is 28" tall for the desired 40% NDF.

To achieve the desired NDF it is necessary to begin cutting at NDF values slightly lower than the desired value assuming some harvest and storage losses which the above alfalfa height values reflect. For example 28 inch tall alfalfa is closer to 38% NDF but you will need to start then to end up at 40% NDF.

Predicted days to cut are based on daily NDF increases for grasses of 1% point, 50/50 mixed stands of .8% points and alfalfa of .5% point. Typically, NDF increases about 0.8 to 1.2/day for grasses expecting the lower end of that range in cooler weather and the higher end in warm. Alfalfa NDF increases about 0.4 to 0.7/day again figuring the lower end of that range with cool temperatures and the higher in warm. See the below attached fact sheet on Predicting Spring Fiber Content of Forages for more details.

Below is this week's chart, but you can use the location and elevation as a guide to conditions that may be similar to your own. Always check your fields to verify your heights and conditions!

Not much to report yet beyond heights, though as usual, locations in the eastern part of our region are a bit ahead. In fact, you may be ready to harvest pure grass hay soon if you're cutting for top quality.

So keep an eye on your grass development and harvest before it heads out (along with its feed value):

To summarize and maybe make it easier for those whose locations aren't listed, here's a chart showing the relationship between elevation and alfalfa heights across our region. If your location isn't listed, you can roughly estimate alfalfa's height within a few inches based on the field's elevation; just follow the line. This week, the general decrease in alfalfa height is by about an inch for every ~320 ft rise in elevation, and you shouldn't expect to see 10" alfalfa above ~700 ft above sea level:

Alfalfa measured by Dave Balbian, Craig Brown, Ashley McFarland, Erik Smith, Ken Smith, and Nicole Tommell.

See the attached Grass Information Sheet Series Information Sheet 22: Predicting Spring Fiber Content of Forages.