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ArticleVolume Number June 13, 2019

How to decide on the best time for the first cut?

Comment décider du bon moment pour la première fauche de plantes fourragères

According to the AgWeather Quebec site on June 3rd, many areas of Quebec were behind by 40 – 90 degree-days (base = 5 degrees Celsius) as compared to averages from 1981 to 2010. Although some have finally been able to get out the mower in some areas to the south, overall there is a marked delay on the date of first cut in Quebec. This will definitely have an impact on subsequent cut dates, but this doesn’t make going after maximum yield and quality it any less important.

In this context, it is even more important than ever not to rely on calendar dates to plan your first cut. Instead, we need to rely on agronomic and meteorological indicators.

How to choose the best time for the first cut?

The choice of timing for your first cut is best made while considering the following three indicators:

  1. The accumulation of degree-days
  2. Yield and nutritional value indicators for timothy grass
  3. Cutting height for alfalfa stems

1. The accumulation of degree-days

Degree-days are units that are used to measure heat. They are calculated according to excesses in average daily temperature as compared to the threshold of 5⁰C over 24 hours. At about 300 degree-days, you should be nearing optimal harvest stage. Time to get out walking in your fields! To monitor the accumulation of degree-days in your area you can visit the AgWeather Quebec site.

2. Yield and Nutritional Value Indicators for Timothy Grass

This tool, available on the AgWeather Quebec site allows you to plan your first cut according to your objectives for yield and quality (NDF content) for timothy grass.

3. Alfalfa Stem Cutting Height

With the help of an plate meter (or a good old-fashioned wooden ruler!), measure the most mature plant in several 1 sq. ft. sections and then take an average of the results.

Plate meter

  • In a meadow that is made up mostly of alfalfa, aim for a stem height of 71 cm (28 inches) which is the flower bud stage.
  • In a meadow that is 50/50 alfalfa/grass, aim for an alfalfa stem height of 55 cm (22 inches). The difference in height is because grasses mature more quickly as compared to legumes. It is therefore important for the first cut to be earlier for higher quality forage.

If you have any questions, be sure to call on your advisor or share them with us in the comments section below.