Alfalfa, the crop with the largest acreage in California, could well emerge as a survivor in the state hard hit by drought.
“This plant is a tough plant,” said Dan Putnam, alfalfa and forage specialist with the University of California at Davis. He believes the deeply-rooted plant “will likely survive once the plant is rehydrated,” and he cited previous research trials that showed its ability to survive in the face of deficit or nearly no irrigation.
Putnam’s observation came during an alfalfa and forage field day at the Kearney Ag Center in Parlier, where he also cited high costs for alfalfa hay this year ($200 to $350 per ton), which is proving to be an incentive for growers to value yield over quality at a time when production is down as much as 10 to 20 percent.
GMO hay exports
He also warned exporters of hay to take care to guard against pushing genetically engineered hay into markets where it is not wanted. With 10 to 12 percent of Western alfalfa going abroad, he said, an important first step is to test the seeds used to grow the crop.
Other topics discussed at the field day included salinity in alfalfa, irrigation of forage and grain sorghum, the nitrogen benefit of alfalfa-wheat rotation, distribution uniformity in surface irrigation systems, management and control of aphids and an update on small grains for silage.
Putnam resurrected some advice on cultivar choice he had given at previous field days. The gist of it: Don’t pinch pennies when choosing seed; the payoff differential that can come with a quality, higher-priced seed can make that choice well worthwhile despite the higher cost per acre for planting.
He said growers need to take into account multiple factors beyond yield, including disease resistance and quality characteristics. He recommends looking at multi-year trial results and choosing from the top performing one-third of the cultivars.
Putnam said alfalfa seed is most vulnerable to taking on genetically modified traits, but the prospect of a “gene flow risk” between fields of hay is low, though not impossible.
“You should know what your neighbors are growing,” he said, adding that coexistence between growers of GMO alfalfa and non-GMO alfalfa hay is possible.
Putnam said he would like to see a “grower-industry led bottom up approach” to enable diverse systems to survive.
Here are some other observations during the workshop:
Alfalfa can supply significant amounts of nitrogen grown in rotation with wheat, said Eric Lin, a graduate student with the Department of Plant Sciences at UC Davis.
Lin is working with Putnam to quantify the role of alfalfa in nitrogen-fixing for subsequent crops.
Putnam said between 150,000 and 200,000 acres in California are rotated out of alfalfa each year. He said growers can save money by spending less on nitrogen that may not be needed, and they can better comply with state restrictions on nitrates moving into groundwater if those contributions can be nailed down.
Jeff Dahlberg, director of the Kearney center, talked of forage and grain sorghum and the importance of taking into account varietal and site differences.
He pointed out sorghum is widely grown in West Texas and Kansas, “and we want to find out how it looks in California.”
Crop management challenging
Managing the crop can be challenging, he concedes, because some growers may have some mistaken notions: “It is not corn; it’s a different animal.”
And to fully derive the greatest energy from the crop, he said, it’s important to adjust choppers in machinery to grind properly.
Brown mid-rib sorghum has a tendency to lodge, he said, and “needs to be cut earlier.” He said researchers are studying use of a gene that may supply more strength to the stem, enabling it to stand better.
Adding too much nitrogen and water can also cause dislodging of that and other varieties.
Bob Hutmacher, UC Cooperative Extension specialist, is working with Dahlberg on irrigation management research in sorghum.
Dan Munk, UC farm advisor for Fresno County, talked of the importance of distribution uniformity in surface irrigation. It’s basically about maximizing the beneficial use of applied water, he said, something that can be particularly challenging during a drought.
Soil infiltration rates
Soil infiltration rates and variable surface intake rates compound the problem of arriving at uniformity with surface irrigation, Munk said, adding that infiltration rates vary throughout the season.
He said infiltration can be increased with practices that include adding organic matter and salts such as gypsum and through tillage.
Pete Goodell, with the UC statewide integrated pest management program, talked of aphid pests, including the blue alfalfa aphid, which posed a particular problem in 2014 with an early outbreak in January, in part due to stressed fields.
The good news he said was that “PCAs (pest control advisors) and farmers jumped on it early and control was good where it was caught early.”
A challenge to alfalfa growers, he said, is “alfalfa has a very limited range of registered insecticides” and none in the neonicotinoid class.
Steve Wright, UC farm advisor for Tulare and Kings Counties, gave an update on small grain silage.
He said cold weather and heavy freezes brought a decline in wheat production this year.
Stipe rust resistant varieties
Stripe rust resistant varieties are taking the place of those that are not and growers continue to keep their guard up against that threat. Wright said it is important that growers pay attention to rust reports in other areas because spores are wind-borne and can be disseminated hundreds of miles away.
Wright said the California Wheat Commission’s Weekly Bulletin is a good source of information on outbreaks.
He added that cool, wet conditions with intermittent fog, dew and rain are most favorable for infection and spore production.
Wright recommends diversifying plantings in case new races of stripe rust emerge.
He cited a long list of chemicals that can be used to keep stripe rust and weeds under control.
Michelle Leinfelder-Miles, a UC farm advisor for multiple counties in the Delta, talked of salinity management in alfalfa, a particular challenge this year given a shortage of water for leaching out salts.
She said salt impairment may be visually identifiable by white or black crusts on the soil surface, wet spots on the soil surface, marginal leaf burn or the presence of salt-tolerant weeds.
Leinfelder-Miles said if a grower has access to more than one source of irrigation water, it’s best to use the best quality water available on seedling alfalfa.
She shared a smart phone application called Soil Web than can assist in identifying the best alfalfa sites. It’s at http://casoilresource.lawr.ucdavis.edu/drupal/node/902.