An established alfalfa plant has a deep taproot allowing it to extract moisture from the soil and continue growing even under drought conditions, says Rory Lewandowski, an agricultural and natural resources educator for OSU Extension.
And while the plants can go into a prolonged dormancy in drought conditions and still recover when it rains, the short-term forecast calls for continued hot, dry weather. So growers whose plants have regrowth beginning to bloom at 4 to 6 inches need to know that there will be little additional tonnage gained by delaying harvest, Lewandowski says.
"The bottom line is that drought-induced moisture stress can cause plants to move through maturity stages quicker, and plants bloom sooner on fewer and shorter stems," he says. "The key here is that we're not going to have a lot of growth. So while quality may be improved, quantity is reduced."
With this in mind, growers may want to consider letting the plants approach 100% bloom before harvesting to allow the plant to build nonstructural carbohydrate reserves, Lewandowski says.
Growers who decide to cut their alfalfa stand under drought conditions should cut them at the normal height, which will allow them to gain optimum yield, he says.
But some growers may find that there isn't enough quantity to make a machine harvest cost effective, Lewandowski says.
"In those cases, it's much more economical to let livestock salvage a low-tonnage yield by grazing the alfalfa," he says.
Those who choose that option need to take precautions to prevent livestock bloat, Lewandowski says, including not grazing alfalfa when dew is on it, making sure stocking density is high enough to prevent animals from grazing only the tops of plants, and potentially using a bloat preventive.
"Growers are recognizing that in a drought situation, they have to think about different management strategies," he says. "We're seeing above-average temperatures and below-average rainfall, which is not a good combination for anyone.
"From our forage crops, agronomic crops and field crops, everyone is feeling the stress from this lack of moisture and extreme heat. So some producers are beginning to make plans, including anticipating where they can find some other hay sources and thinking about what this will mean for fall and winter feeding."