Posts Tagged: alfalfa

California groundwater could get recharging help from alfalfa farms

When California experiences drought due to a lack of rain and snow and the reservoirs don't fill up, people pump water out of the ground to meet their needs. But that practice has its limits, as groundwater aquifers -- underground layers of porous rock -- get depleted, similar to how water squeezes from a sponge.

Many of California's groundwater aquifers, especially in the San Joaquin Valley, are critically overdrafted. They are being depleted faster than they are being recharged by water from the surface percolating through the soil to groundwater. Overdrafting is a concern because California relies on groundwater aquifers as a water storage and supply resource. They must be protected to ensure water security in the future. 

To direct surface water back into the aquifers, recharge basins are built, but they are limited in number and volume. Thinking of agricultural fields as potential recharge basins opens the possibility of increasing the number of locations where groundwater aquifers can be recharged. 

Alfalfa is a crop that has a unique potential to support this practice because it is widely grown in the San Joaquin Valley and, in many cases, the plants are dormant or semi-dormant during the winter months. University of California researchers Helen Dahlke, Nick Clark and Khaled Bali are investigating how alfalfa copes with additional water in the winter and early spring, when snowmelt runoff occurs, for groundwater recharge.

“We hypothesized that water can be recharged in dormant and early regrowing established alfalfa fields successfully, and with little to no harm to the plants and the productivity as far as the farmer is concerned,” said Clark, a UC Cooperative Extension farm advisor. 

The findings have shown great promise for recharging groundwater without negatively impacting alfalfa yield but may diminish quality. “You could do recharge in winter and then turn the water off completely and still get a cutting or two of alfalfa before the summer,” said Bali, a UCCE irrigation water management specialist.

Like Bali, Clark thinks alfalfa growers could use their fields for recharging groundwater while taking steps to limit loss of crop value. 

“We did find that the practice of recharging groundwater in alfalfa fields can have a negative impact on the feed quality of the alfalfa when first harvested after the flooding,” Clark said.

“One big recommendation we have is that the alfalfa fields should be in their later years of production so if something disastrous happens, there is not so huge of investment return lost,” said Clark. “There is current research being conducted by UC Cooperative Extension specialists Dan Putnam and Khaled Bali examining practical solutions on the farm level that growers can implement to minimize the risk of damage to alfalfa when also flooding fields for groundwater recharge.”

Clark emphasized that farmers face incredibly complex water-management issues today. The drivers that influence their decisions reach far beyond the farm, so he collaborates with UC Davis professor Helen Dahlke, who studies integrated hydrologic sciences.

“It requires an approach from multiple disciplines to address that complexity,” he said. “Helen brings hydrological expertise, while I can focus on agronomy. So the information we provide is more holistic and relevant on a larger scale, but still practical and applicable for farmers.” 

Grower input on the research findings has been critical to their success. “With their feedback, we were able to reform some of the project methodologies to achieve results that were even more relevant to the local conditions,” said Clark.  

With the prolonged drought, innovations in groundwater recharge are becoming more crucial. Future research will continue to focus on how growers can use their land in multifaceted ways to improve California's water sustainability far into the future. 

Organic alfalfa hay cost study released

A new study that outlines costs and returns of establishing and producing organic alfalfa hay has been released by UC Cooperative Extension, the UC Agricultural Issues Center and the UC Davis Department of Agricultural and Resource Economics.

High-quality organic alfalfa hay is an important ingredient in milk-cow feed rations for organic dairies. Organic dairy farms are required to use organic feed and allow cows to graze for part of their forage. Organic alfalfa hay comprises a major source of forage for the industry.

In 2019, organic dairy farms in California produced about 900 million pounds of milk — just over 2% of California milk output production, according to co-author Daniel Sumner, director of the UC Agricultural Issues Center and professor in the UC Davis Department of Agricultural and Resource Economics.

“Demand for organic alfalfa production has grown, including demand from dairy, horse, sheep, goat, and beef producers, but is still a small share of total alfalfa production,” said Daniel Putnam, UC Cooperative Extension forage specialist in the Department of Plant Sciences at UC Davis and co-author of the study. “However, understanding organic production methods and costs is very important for California's organic hay farmers.”

The new study estimates the costs and returns of establishing and producing organic alfalfa using flood irrigation in the Sacramento Valley, north and south San Joaquin Valley, and the Intermountain Region. The 100 acres of organic alfalfa is rented for $345 per acre annually and the alfalfa stand life is four years after the establishment year.

Input and reviews were provided by UCCE farm advisors and specialists and growers. The authors describe the assumptions used to identify current costs for organic alfalfa establishment and production, material inputs, cash and non-cash overhead and a ranging analysis table, which shows profits over a range of prices and yields.

“This cost study provides information on how to grow alfalfa hay organically,” said Rachael Long, study co-author and UC Cooperative Extension farm advisor in Yolo County. “The research that went into developing these practices represents a significant investment by UCCE farm advisors and specialists and California alfalfa farmer collaborators. We are pleased to team up with economics and cost study experts to provide this study, which indicates potential profits in growing this crop for the organic dairy market.”

The new study, “Sample Costs to Establish and Produce Organic Alfalfa Hay, California - 2020” can be downloaded for free from the UC Davis Department of Agricultural and Resource Economics website: http://coststudies.ucdavis.edu. Sample cost of production studies for many other commodities are also available on the websites.

For an explanation of calculations used in the study, refer to the section titled Assumptions. For more information, contact Jeremy Murdock, UC Agriculture and Natural Resources, Agricultural Issues Center, Department of Agricultural and Resource Economics, at (530) 752-4651 or jmmurdock@ucdavis.edu. To discuss this study with a local extension advisor, contact the UC Cooperative Extension office in your county: https://ucanr.edu/About/Locations.  

The leafcutter bee is an efficient alfalfa pollinator

The hard work put in every summer by leafcutter bees was spotlighted by KQED Science, which took a Deep Look at an introduced pollinator that makes bountiful alfalfa seed production possible in California.

For facts behind the 'gee whiz' video, KQED turned to Shannon Mueller, UC Cooperative Extension alfalfa advisor emeritus, who helped introduce leafcutter bees in the early 1990s.

What makes leafcutter bees special? It's their innate ability to 'trip' alfalfa flowers, which is beautifully explained and shown - in slow motion - in the Deep Look video.

Cutters were “game changers” in the alfalfa seed business because they're much better at pollinating alfalfa than honeybees, Mueller said. Cutters trip 80 percent of flowers they visit, compared to honeybees, which only trip about 10 percent.

Leafcutting bees pollinate alfalfa, allowing the plants to form seeds. The seeds will be grown to make nutritious hay for dairy cows, giving credit to leafcutter bees' for their labor on the first step to making ice cream.

Birds are beneficial too!

Across the globe, scientists have shown that birds can be farmer allies. Insectivorous birds feed on damaging insect pests in many crops including coffee, cacao, oil palm, corn, cabbage and apples. Raptors, including hawks and barn owls, feed on rodents, including gophers, voles and mice (see blog, Barn owls help clean up rodents naturally).

Despite this deep historic knowledge that birds are important predators of crop pests, over time the perception of birds as natural enemies of pests has been generally replaced with the idea that birds are often major crop pests themselves. Indeed, some bird species — like some types of insects — can cause trouble for farmers, but many others — especially those that eat insects and rodents — can be beneficial.

 

Do birds control insect pests on farms in California's Central Valley?

They do! Recent studies by Dr. Sacha Heath, UC Davis, and Rachael Long, field crops and pest management advisor, UC Cooperative Extension, showed that birds help control insect pests in walnut orchards. Dr. Sara Kross (UC Davis postdoctoral alumnus, now with Columbia University) showed that birds help control alfalfa insect pests.

Birds are voracious predators of codling moth pests in walnuts

Codling moth is a major worm-like pest that infests walnuts, apples and pears. The larvae go dormant during winter, living in cocoons in crevices in trees. Adult moths emerge in the spring, lay eggs and infest crops.

 

We evaluated bird predation of codling moth using “sentinel prey” and exclosure cages. We glued codling moth cocoons to walnut trunks and covered them with cages, allowing insects and spiders to access the cocoons, but not bird predators. This allowed us to count how many larvae were eaten inside and outside of the cages to estimate pest reduction by birds.

 

 

 

What did we find?

Natural enemies, like parasitic wasps and lacewings, alone reduced codling moth larval numbers by 11%; adding birds into the pest control system reduced them by 46%! Nuttall's woodpeckers and white-breasted nuthatches did a lot of the work; these birds travel up and down the trunks of trees, searching for insects.

Above, a white-breasted nuthatch preys on a codling moth larva “sentinel cocoon” on a walnut tree. Video by Sacha Heath.

 

Alfalfa weevils are no match for insectivorous birds

Alfalfa weevils are key pests of alfalfa, reducing yields and hay quality if left uncontrolled. Dr. Sara Kross looked at bird predation of this pest by excluding birds from alfalfa plants via cages, and counting the number of weevils inside and outside the cages. She found that birds reduced the number of weevils by more than 30%, showing their importance in helping to protect alfalfa from this serious pest.

 

 

Does field edge habitat, like hedgerows, help attract beneficial birds?

Yes! Hedgerows are important habitat for beneficial birds, serving as nesting, foraging and roosting sites. In a study in the Sacramento Valley, crop margins with hedgerows, tree lines and riparian buffers harbored up to six times more birds and up to three times more bird species than bare or weedy margins.

Walnut orchards adjacent to hedgerows and riparian areas had higher numbers of beneficial birds along with more species. In alfalfa, there were more beneficial birds in fields when at least two tall trees were present along the field edges. More beneficial birds were associated with better pest control, that is, fewer codling moth cocoons and alfalfa weevils.

 

Birds have large territories, fly long distances, and are influenced by what happens on the farm as well as by what happens in the landscape around the farm. For example, we found that codling moth predation by birds greatly increased in walnut orchards as the amount of habitat in the landscape around the orchards increased (including hedgerows, tree lines, riparian and oak woodlands, and grasslands).

 

Will hedgerows increase the numbers of pest birds?

Pest birds are present on farms regardless of field edge habitat (such as weedy vegetation or hedgerows). Cases will be different, depending on the crop, but in the fields and orchards of Yolo County, researcher Hillary White (formerly with UCCE and now with U.S. Fish and Wildlife) found that three of the most common avian crop pests (American crow, red-winged blackbird and Brewer's blackbird), were up to 10 times more abundant in agricultural fields with bare or weedy margins than in fields with hedgerows.

 

What can I do to attract beneficial birds to my farm?

Our avian research team has been quantifying the conditions under which birds are helpful or harmful to growers. We are looking for ways to help farmers create bird habitat on their farms to harness the beneficial pest control services birds can provide, while also protecting crops from the damaging effects of some bird species. This information is available in the new publication “Supporting Beneficial Birds and Managing Pest Birds,” co-authored by the Wild Farm Alliance and Drs. Kross and Heath, and technically advised by UC Cooperative Extension and several farmers. This is a user-friendly guide for farmers and conservation practitioners, with the goal of co-managing farmlands for biodiversity and farming.

 

Dr. Sacha Heath received her PhD from UC Davis's Graduate Group in Ecology and will soon be starting a postdoctoral fellowship with the Living Earth Collaborative in St. Louis, Missouri.

A white-breasted nuthatch preys on a codling moth larva “sentinel cocoon” on a walnut tree. (Video still: Sacha Heath)

A white-breasted nuthatch preys on a codling moth larva “sentinel cocoon” on a walnut tree. Video still by Sacha Heath.

Mandarin drought tips featured in final video of drought series

Because periodic droughts will always be a part of life in California, the UC California Institute for Water Resources (CIWR) produced a series of videos to maintain drought awareness and planning, even in years when water is more abundant.

The final video of the three-part series, which focuses on drought strategies for citrus, was launched April 6 on the UCTV Sustainable California channel. The first episode, which centered on alfalfa production, premiered Feb. 2 on the UCTV Sustainable California channel. The second video, on almonds, was launched March 2 on Sustainable California. A trailer with clips from all three episodes is here.  

The videos are inspired by a collection of 19 drought tips produced by CIWR in collaboration with UC Agriculture and Natural Resources researchers during the drought of 2010-16. The tips cover a broad spectrum of California crops, from alfalfa to walnuts. Topics also include salt management, use of graywater in urban landscapes, and the use of shallow groundwater for crop production. 

The drought tips collection and the drought tip videos were sponsored by the California Department of Water Resources. Following are links to each of the videos:

Drought strategies for alfalfa

The CIWR drought tip series opens with Cannon Michael of Bowles Farming in Los Banos. The alfalfa grower works with UCCE specialist Dan Putnam. “There's a lot of misunderstanding about alfalfa as a crop,” Michael said. “It does take water to grow it, as with anything, but you get multiple harvests of it every year.”

Drought management for California almonds

The second episode features almond producer Raj of Meena farms. He works with David Doll, UCCE advisor in Merced County. “One positive of this drought,” Meena said, “is that it has forced us all to be more efficient in how we use our water.”

Irrigating citrus with limited water

The series finale features Lisa Brenneis of Churchill-Brenneis Orchard in the Ojai Valley of Ventura County. She worked with UCCE advisor Ben Faber to install a new water-efficient irrigation system. “Irrigation is the only job we really have to do,” Brenneis said, “and we have to get it as right as we can.”

For a complete list of drought tips, see http://ucanr.edu/drought-tips.

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