From Cornell University Cooperative Extension, for our customers in New York and Northern states
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.
At a number of locations orchardgrass should be ready to harvest momentarily. Dry conditions seem to be the norm so the grass growth doesn’t appear to be as dense as it should be for this time of year. The observation is that spots in grass fields that have held more moisture are considerably denser than drier areas. Alfalfa fields are in much better shape in 2013 compared to 2012 when frost heaving and spring frost injury was common.