Temperature, humidity, wind speed, and soil moisture content all are important, but solar radiation has the greatest impact on drying rate.
By: Bruce Anderson, UNL Forage Specialist
Haying season is just about upon us. Weather reports soon will be the most important news of the day. Fortunately, there are ways to hasten hay dry-down to beat the weather.
Does it seem to you that this spring has been cloudier than most springs? Now maybe you’re wondering why I’m talking about clouds when this article is about hay dry-down. Well, the reason is that, other than rain itself, the most important weather factor that affects rate of hay dry-down is sunlight. Temperature, humidity, wind speed, and soil moisture content all are important, but solar radiation has the greatest impact on drying rate. In fact, research has shown as much as a 10-fold increase in drying rate as solar radiation changes from heavy cloud cover to full sunlight. No other factor affected drying rate even half as much.
So how do you use this information? Obviously, you can’t control how much sunlight you receive. But, you can watch weather reports and try to cut hay during sunny weather. Okay – that’s stating the obvious. Another thing you can do, though, is spread your cut hay out in as wide a swath as possible. This will expose more of your hay to direct sunlight, enabling it to absorb as much energy from the sun as possible to evaporate moisture out of your hay. This may cause a little more sun bleaching than thick windrows, but most of the time fast dry-down is more valuable than green color.
Also, mechanically conditioning your hay and turning it gently after the top gets dry to expose moister hay underneath the swath will help hasten dry-down.
Make hay while the sun shines is an old, old saying but today’s science has shown how true it really is.