We have begun monitoring of 1st cutting for quality this year. 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 we say 100% grass stands should be cut when nearby alfalfa is 14 inches tall to achieve the desired 50% NDF.
Begin cutting 50/50 mixed alfalfa and grass stands when nearby alfalfa is 22 inches tall for the desired 44% NDF.
Begin cutting 100% alfalfa stands when alfalfa is 28 inches tall for the desired 40% NDF.
The desired NDF for all grass fields is 50%, 50/50 mixed alfalfa and grass fields is 44%, and pure alfalfa stands is 40%. 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. Predictions are adjusted for the coming week's weather and right now we are assuming normal growth.

In the attached tables locations around the region are listed where we have measured alfalfa height. You can use the location and elevation as a guide to conditions that may be similar to your own.
For May 9 growth has slowed considerably given the cold temperatures of the past week. On average alfalfa only gained 3 inches, which given the delay in field work due to cold rainy weather, is a good thing. There may be opportunities to harvest for quality given current weather predictions for the next two weeks. Start a list prioritizing which of your fields have a chance for highest quality and those that are past prime or are likely to be too wet to harvest without rutting up fields or worse.
At some of our locations fields are past for grass harvest and are at or approaching time for alfalfa grass mixes to be harvested. Check your fields so you know what stage your haycrop is in.
Credit to David Balbian, Ashley McFarland, Mark Schmidt, and Bill Gibson for gathering the info in the field.

As always use information in the attached table as a guide to know when to harvest by checking your fields! Next report May 16!


May 9, 2017 First Cutting Forage Quality Update (pdf; 532KB)