Environmental Conditions Affect Time To Safe Hay Baling

Environmental conditions that exist when forages are ready to be harvested influences the amount of hours that it takes to get to a safe baling moisture. A growing forage will have 75 to 80 percent moisture. A moisture content of 20 percent is considered a safe baling moisture for small rectangular bales and will be slightly less for large round bales and large rectangular bales. The following tables are from the Purdue Forage Field Guide (Purdue publication ID-317) and provide useful information regarding the effects temperature, relative humidity, and soil moisture condition have on the time it takes from cutting to baling.

When relative humidity is 90 percent, cut hay will never get to a safe baling moisture content of less than 20 percent moisture regardless of temperature (Table 1). With a relative humidity of 70 percent or less, the higher the temperature the lower the predicted moisture will be for hay in storage, although a 70 degree F temperature at 70 percent relative humidity will not achieve a safe baling or storage moisture level.

Effects of soil moisture condition and solar radiation on the number of hours to achieve 20 percent moisture alfalfa are found in Table 2. This research indicates that the number of hours when conditions are cloudy with wet soil moisture are approximately three times longer than when sunny and dry soil conditions occur.

It is critical that environmental conditions be considered when making dry hay. Haymaking conditions are likely to never be the same within a harvest season.

Table 1. Predicted Final Moisture Content Of Baled Hay

Table 2. Predicted Hours To Dry Alfalfa From 80% To 20% Moisture

Raking hay into a windrow before baling occurs. (Photo Credit: Keith Johnson)