The big question is when to start the first crop harvest? The Alfalfa is now tall enough in many fields if you look at the PEAQ measurements (Predictive Equations for Alfalfa Quality) for the North West Minnesota area, at least in Otter Tail County.

At 22” tall and in the vegetative stage of growth the RFV is 200, at 25’ tall and in the vegetative stage of growth you are at 185 RFV. The harvest process will cause a loss of RFV of about 20 points. The rate the alfalfa is maturing at is between 2 to 5 points per day so if your goal is 150RFV forage and it takes 4 days to harvest your first crop you need to start when the alfalfa is at between 175 to 185 RFV in the field. 15 points + 10 to 20 points for the loss due to maturity gives you a 25 to 35 point loss you must add to the goal of 150 RFV target thus a start point of some ware around 180 to 200 RFV is need.

Now how about the rain? Mike Rankin and Dan Undersander have some good information on “Rain Damage to Forage During Hay and Silage Masking” the following are excerpts from the article:

Rain that occurs between the time forage is cut and harvested causes both yield and quality losses that reduce the value of the crop as an animal feed and a marketable commodity. Weather-induced losses can be caused by:

• Increased and prolonged plant respiration that reduces soluble carbohydrates and the overall energy content of forage.
• Leaching of soluble carbohydrates, protein, and certain minerals.
• Leaf shattering and loss, removing the highly digestible and high protein portion of the forage.
• Microbial activity that metabolizes soluble carbohydrates, reduces forage energy content, and possibly produces harmful mycotoxins.
• Color bleaching.

My hay is ready to cut but there’s rain in the forecast. Do I cut or not?
This dilemma has faced forage producers for years. Because the impact of rainfall on loss of forage yield and quality varies with timing, amount, and duration, there is no easy answer. The range in economic loss from rainfall for a particular hay crop can range from minimal to over 100 percent, if the forage has to be chopped back onto the field. However, based on previous research studies and applied management practices, we can categorize factors that increase our risk of cutting hay when the weather forecast is somewhat less than perfect. These are presented in Table 1.