Hastening Hay Dry-Down

Hastening Hay Dry-Down

Nebraska has faced less than optiumum weather for making hay the last couple of weeks. While the continued rains are obviously a problem, cool, cloudy days are also an issue. 

Sunlight is one of the most important factors affecting the rate of hay dry-down. Temperature, humidity, soil moisture content, and wind speed 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.

In addition to taking advantage of any warm, sunny days for cutting, consider these steps for hastening hay dry-down:

  • Spread cut hay out in as wide a swath as possible to expose more hay to direct sunlight.  This does two things. Sunlight keeps stomates open on the leaves, which is the fastest way for moisture to exit the plant. Stomates in the dark inside or bottom of windrows will close, preventing rapid moisture loss.  Wide windrows also enable your hay to absorb as much sun energy as possible to heat and evaporate moisture out of your hay.  This may bleach hay more than thick windrows, but fast dry-down usually is more valuable than green color.

  • Mechanically condition your hay and turn it gently after tops dry to expose moist hay under the swath and 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.