What is in this article?:
- Five Ways To Get The Most From Your Alfalfa
- Fertilize, Harvest and Irrigate
Alfalfa is a tough crop. It can handle poor seedbed preparation, weed infestations or improper irrigation.
But just because the legume is forgiving doesn’t mean mistakes won’t add up and hurt profitability, says Steve Orloff, University of California Cooperative Extension director in Siskiyou County.
“Where I am, some growers attain 8 tons or slightly more an acre. Others only get 4-4.5 tons/acre,” he says. “There are significant things you can do to improve the productivity of your operation.”
Orloff suggests the following five main areas in which growers can increase yield and their bottom lines.
Establish strong stands. Establishing alfalfa is a bit like buying a new vehicle. You’re going to have it for a while, so you better get something that’s reliable and high quality. “You want a long-lived stand that’s vigorous and is going to persist for a number of years,” he says.
Because seed depth affects alfalfa emergence, test whether your field’s seedbed is firm enough. If your boot heel sinks to ½” deep, that’s how deep the seed will be planted. About 60% of plants seeded at ½” typically emerge; that drops to 48% emergence for plants seeded 1” deep, according to Orloff. Only about 2% of alfalfa emerges if planted deeper than 2”.
The farm advisor is a fan of late-summer or fall plantings, especially for his Intermountain West growers. Temperatures cooler than 68° F and less than 12 hours of daylight promote root growth and crown development; the flip side promotes shoot growth. “The reason fall planting is better is you’re going into cooler temperatures, so you’re getting more root growth over shoot growth.”
Late-summer plantings also contend with less weed pressure than spring plantings if done after the window for summer annual weeds. Late-summer or fall establishment typically produces higher yields, which can help pay for the water required to germinate the stand. Spring plantings often get enough rain for emergence, he adds.
Control weeds early. Growers often underestimate weed infestations in new stands and wait too long to treat them. Usually, the earlier herbicide is applied the better; for seedling alfalfa, apply at the earliest growth stage listed on the manufacturer’s label.
Some growers let weeds grow and then take early cuttings to clean up, an approach Orloff doesn’t recommend. The stand may recover, “but you’re really sacrificing the long-term profitability of that stand.”
In one study Orloff conducted on newly seeded alfalfa, three postemergent herbicides – Pursuit, Buctril and 2,4-DB – controlled nearly 100% of weeds if applied when weeds were at the two- to three-trifoliate-leaf stage. At the four- to six-leaf stage a month later, each herbicide was much less effective.
“You had the same intent and used the same amount of herbicide, but you got approximately half the control.”
Roundup Ready alfalfa stands should be treated at the three- to five-leaf stage. There is temptation to wait longer because glyphosate kills large weeds, but by that point there already will be plenty of competition. Treating too early also can cause problems, because glyphosate only controls emerged weeds, and more can germinate in bare soil with no alfalfa canopy.
Timing is critical for winter weed management in established stands. On conventional alfalfa, apply herbicides before the crop breaks dormancy or risk setting back growth. Growers may think they’ll get their money’s worth with an application after alfalfa breaks dormancy because the results look dramatic, but they could also lose up to O.25 ton/acre.