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.
Fertilize, Harvest and Irrigate
Test, then fertilize. Orloff suggests growers fertilize using a prescription approach rather than a recipe in which they apply the same nutrients every year. Soil and tissue tests should be utilized so growers know what nutrients are missing, then tailor their fertilization programs to match.
Don’t skimp on sampling, he says. “A lot of alfalfa growers don’t (test), and if they do it’s only before planting, not during the life of the stand.” Cost shouldn’t be a deterrent; tests can pay for themselves several times over, he adds.
“Yield potential is limited by the most deficient nutrient.” Grid sampling showing where nutrients are lacking in a field is a better approach than using average nutrient levels of the whole field that can cover up deficient areas. “Our fields aren’t that uniform.”
Harvest for maximum returns. In years when hay prices spike, growers who sell their hay may want to focus on quantity over quality.
“We’d like to see growers adjust their cutting schedules for the economic conditions that year,” Orloff says. “It’s the yield-quality trade-off.”
It may seem counterintuitive, but data from California’s Central Valley shows that, when hay prices rise, the spread between prices of supreme- and fair-quality alfalfa actually shrinks. When prices fall, that gap grows.
For example, in 2008 the average price of supreme-quality alfalfa was about $240/ton. For fair-quality alfalfa, the price was just over $200/ton. Two years earlier, when supreme hay sold for about $160/ton, the spread between the two was more than $60.
Better-manage water use. Nothing, Orloff says, limits yield more than poor irrigation management. That’s why he recommends soil moisture sensors to measure moisture levels at different depths. Sensors can help growers know when or whether to irrigate, whether they filled their soil profiles, and whether they need to make changes.
As a general rule, the amount of irrigation applied over a season should resemble a bell curve, with peak water application in midsummer when crop water use is highest. A steadfast rule of two to three irrigations per cutting isn’t always accurate. “There are a lot of cases where growers are under-irrigating in the summer and over-irrigating in the fall because they have the same number of irrigations between cuttings.”
Sensors can alert growers when fields are getting too dry, so they can irrigate enough to keep the soil moist without conflicting with harvest.
Orloff has a few simple tips to make water go a long way. Always check soil moisture content early in the season to know when to begin irrigating. “Sometimes you get spring rains and you think you’re fine, but you’re only wet on the top 6” of soil.” Make sure to begin the season with a full profile, and try to maintain adequate moisture throughout cuttings because it’s hard to play catch-up.
If you’re short on water, irrigate in spring when you get the highest yield.