Posts Tagged: UC Davis

Understanding cattle grazing personalities may foster sustainable rangelands

To better understand individual grazing patterns, researchers went to the UC Sierra Foothill Research and Extension Center in Browns Valley and tracked 50 beef cows fitted with GPS collars. File photo by Ray Lucas

Matching herds to landscape can support animal growth and ecological needs

Not all cattle are the same when it comes to grazing. Some like to wander while others prefer to stay close to water and rest areas.

Recognizing those personality differences could help ranchers select herds that best meet grazing needs on rangelands, leading to better animal health and environmental conditions, according to a new paper from the University of California, Davis, published in the journal Applied Animal Behaviour Science.

“Cattle can actually be beneficial for the rangelands,” said lead author Maggie Creamer, who recently earned her Ph.D. in animal behavior at UC Davis. “Vegetation in rangelands actually need these kinds of disturbances like grazing.”

Ranchers can add elements to the rangeland such as water, mineral supplements and fencing to influence where cattle graze, but little research has been done on how those efforts affect individual cows. Considering personalities could save money.

“If you're spending all this money to add a management tool in order to change the distribution of your animals, that's a huge cost to ranchers,” said Creamer. “Thinking about other tools, or selecting certain animals with these grazing traits, might be a better way to optimize the distribution on rangeland rather than spending a bunch of money for something that may ultimately not pan out for all your animals.”

Effects of grazing

Livestock graze on an estimated 56 million acres in California, and healthy rangelands host native vegetation and animals, foster nutrient cycling and support carbon sequestration.

Uneven grazing can degrade water quality, soil health and habitats. Optimizing grazing — including the even spread of cow pies — can improve the ecosystem while also reducing fuel loads for wildfires.

To better understand individual grazing patterns, researchers went to the UC Sierra Foothill Research and Extension Center in Browns Valley and tracked 50 pregnant Angus and Hereford beef cows fitted with GPS collars.

A cow at the Sierra Foothill Research and Extension Center in Browns Valley being tracked as part of research on cattle grazing personalities. Photo by Maggie Creamer, UC Davis

The research

The cattle, which were tracked from June to August over two years, had access to 625 acres of grasslands and treed areas ranging in elevation from 600 to 2,028 feet. In the second year, a new watering site was added at a higher elevation.

Across the two years, the cows showed consistent and distinct grazing patterns even when water sources changed. Age and stage of pregnancy did not affect patterns, though cattle tended to clump near water and rest sites on hotter days.

The cows that ventured into higher elevations and farther from watering sites had more variability in their grazing patterns than those that stayed at lower elevations near water. That suggests it may be harder for non-wanderers to adjust to some landscapes.

“Thinking about the topography of your rangeland and your herd of cows can benefit both the animals and the sustainability of the land,” said Creamer, who next month begins work as a postdoctoral scholar in North Carolina.

Gauging personalities

Keying in on personality type may sound difficult, but the researchers also found some clues as to how to pinpoint the wanderers and homebodies. Unlike cattle at feedlots, the breeding cow population, especially on rangelands in California and other western states, live largely “wild” lives and are rarely handled, save for vaccinations and weaning.

Research due to be published later this year found that paying attention to individual cow reactions during those events can help determine personalities. The cows that appeared more passive during those handling interactions tended to be nomadic.

“We found that you can maybe predict those hill climbers if you kind of look at how they act when the veterinarian or rancher handle them,” said senior author Kristina Horback, an associate professor in the Department of Animal Science at UC Davis.

Informing practices

For ranchers, the findings could be invaluable, said Dan Macon, a livestock and natural resources Cooperative Extension advisor in Placer and Nevada counties for UC Agriculture and Natural Resources.

“Any time we can improve our understanding of cattle behavior, particularly at the individual level, it can improve how we handle livestock and manage the landscape,” he said.

Macon said that during the recent drought, it was hard to get cattle into higher country, but if ranchers could have selected the nomads, it may have saved money in terms of ranch labor and other efforts.

“If you ask a rancher who has been attentive to their cattle over many years, they know the personalities,” Macon said.

For Creamer and Horback, the research opens new doors into understanding herd behavior and dynamics, one that could be a cheaper alternative to high-tech solutions.

“Animal science tends to look overlook the mind of the animal when searching for solutions to challenges,” Horback said. “It's always been a direct line to genetics for immunity or nutrition, but nothing about the mind of the animal. And that's such a loss. There's so much we can learn from behavior in the end.”

The Russell L. Rustici Rangeland and Cattle Research Endowment supported the research.

This article was first published on the UC Davis News site.

Car fumes, weeds pose double-whammy for fire-loving native plants

In September 2013, a few months after the Springs Fire blazed through the Santa Monica Mountains in Southern California, a team led by Justin Valliere started laying out plots to study how the combination of invasive weeds and air pollution would impact the resurgence of native plants that usually flourish after a wildfire. Their tests tried to mimic nitrogen coming from vehicle exhaust in nearby Los Angeles. Photo by Justin Valliere, UC Davis

Wildflower displays threatened

Northwest of Los Angeles, springtime brings native wildflowers to bloom in the Santa Monica Mountains. These beauties provide food for insects, maintain healthy soil and filter water seeping into the ground – in addition to offering breathtaking displays of color.

They're also good at surviving after wildfire, having adapted to it through millennia. But new research shows wildflowers that usually would burst back after a blaze and a good rain are losing out to the long-standing, double threat of city smog and nonnative weeds.

A recent study led by Justin Valliere, assistant professor in the UC Davis Department of Plant Sciences, found that native wildflowers and other plants that typically flourish following a fire were, instead, replaced by invasive plants on land that received the kind of nitrogen contained in vehicle emissions.

Shooting stars, or Dodecatheon clevelandii, is typical of the native plants that bloom in even higher abundance following a fire and a good rain in the Santa Monica Mountains of southern California. Photo by Justin Valliere, UC Davis

“Many native plants in fire-prone areas rely on fire, and some are entirely dependent on it. Some are even most abundant after a fire,” said Valliere, a UC Cooperative Extension specialist in invasive weed and restoration ecology. “But we found that these fire-following species may be especially vulnerable to the combination of nitrogen pollution and invasive plants.”

That's part of the reason why native plants in these mountains have been declining.

Seeds – banked in the soil and waiting to sprout

The problem faced by native plants can be compared to a drawn-down bank account: Funds withdrawn are not being replaced.

It starts with fire, an important ecological process, Valliere said. Flames burn through plants on the surface and return their nutrients to the soil. Seeds sleeping in the ground wait for the next rain to sprout, then use those nutrients to grow.

“Plant diversity is often highest in growing seasons immediately after a site burns,” he said.

But invading plants have many advantages over native ones. They often sprout earlier, grow faster and create more seeds, all while tolerating drought.

“They're like cheaters,” Valliere said. “They don't follow the same rules.”

Nitrogen, too, is an important piece of every plant's nutrition. They all get a fertilizing boost from nitrogen that floats up in vehicle emissions and falls to the ground. But the invaders use nitrogen and other nutrients to grow faster, winning the race for water and sunlight. As a result, fewer native plants reach maturity, producing fewer seeds that keep their populations thriving.

When the bank balance reaches zero

The 2013 Springs Fire gave Valliere a unique opportunity to study the combined impacts of wildfire and extra nitrogen. He and colleagues from UC Riverside and the National Park Service created test plots in the Santa Monica Mountains where the fire had burned. Then, they added nitrogen to the soil to mimic the amount and type that LA's smog would deposit. Over the study's three years, native plants that typically would have flourished after wildfire instead declined even faster in the plots with added nitrogen.

Native seeds sprouted, but didn't flower. Over time, the soil's bank of seeds drew down.

In spring of 2015, the area that had been burned by the 2013 Springs Fire was again in bloom. The clearwater cryptantha shown here, or Cryptantha intermedia, is a native plant that blooms all over California. It is especially abundant in the coastal south. Photo by Justin Valliere, UC Davis

“Each seed has one chance to flower and reproduce,” Valliere said. “If a seed grows and gets outcompeted, that seed has lost its chance to replenish the seed bank.”

Without the chance to replenish their bank account, native plants will die out, and the whole ecosystem will be thrown out of balance.

“There is inherent value in biodiversity,” Valliere said. “These invasive weeds could prevent the re-establishment of native shrubs after fire, sometimes forever altering the plant community.”

The loss of native plants can have cascading effects on the larger environment, he added. Problems can include the loss of native bees that feed on the flowers, and mudslides when rain makes hillsides unstable.

This problem is likely to repeat in similar areas where biodiversity is highest after wildfires – including parts of the Mediterranean basin, southern Africa and Australia. The addition of city smog “could have serious consequences for the biodiversity of fire-prone ecosystems worldwide,” Valliere warned.

Read the paper, “Nitrogen deposition suppresses ephemeral post-fire plant diversity,” by Justin Valliere, Irina Irvine and Edith Allen.

This article was first published on the UC Davis Department of Plant Sciences website.

Google Weed View? Professor trains computer to spot invasive weed

Johnsongrass patches identified using Google Street View. The yellow boxes were designated by artificial intelligence; the red boxes were drawn by human hand.

Algorithm for AI enables low-cost tracking of invasive plant

To manage johnsongrass, a noxious weed that crowds out cotton and sickens horses, farmers have tried herbicides, burning and hand-pulling. Now, researchers at University of California, Davis, have developed a more high-tech weapon against the invasive weed: artificial intelligence and machine learning.

Using photos from Google's Street View database, UC Davis researchers have tracked down over 2,000 cases of johnsongrass in the Western United States for a fraction of the cost and time that it would take to do drive-by or other in-person surveys. They call their tool Google Weed View.

The advancement could help land managers easily and quickly survey for other problem plants.

“Once the model is trained, you can just go and run it on millions of images from Google Street View,” said Mohsen Mesgaran, an assistant professor in the Department of Plant Sciences at UC Davis. “We have huge flexibility, and its capability can be scaled up very quickly.”

The technique can easily be extended to other plant species. All that is needed is to label the new item in Street View photos and train the algorithm to identify that object in the images.

By providing location information, Google Weed View also offers an opportunity to examine how climate affects the growth and spread of weeds and invasive plants at very large scales.

“I think it can be both useful for management and for people with interests in more basic questions in ecology,” Mesgaran said.

Johnsongrass patches identified using Google Street View. The yellow boxes were designated by artificial intelligence; the red boxes were drawn by human hand.

A colleague's query

Mesgaran began looking at using Google's photo database of roadways, streets and highways after Kassim Al-Khatib, a professor of Cooperative Extension in the same department, asked if he could survey Western states for johnsongrass.

Al-Khatib studies where johnsongrass grows, ways to manage it and how this perennial has evolved to be so prevalent and resilient. He's also working with scientists at the University of Georgia to decode the genome of johnsongrass, which is one of the top 10 most invasive weeds worldwide.

Johnsongrass can crowd out native plants, harbor pathogens and affect agriculture. It grows up to 7 feet tall with flowers that are green, violet, dark red or purplish brown depending on maturity, according to a UC Statewide Integrated Pest Management Program briefing page.

“Johnsongrass is a major weed not just in California but worldwide,” Al-Khatib said. “It's very difficult to control. It's a problem on vineyards. It's a problem for cultivated crops. It's a problem on orchards.”

Google Weed View allows for rapid, convenient scanning. It is continuously updated via everyday users with compatible cameras and images collected by Google. “Instead of a day of in-person driving, we can use AI to determine if johnsongrass is in a county or not,” Al-Khatib said. 

Johnsongrass identified growing near agricultural land using Google Street View. The yellow boxes were designated by artificial intelligence; the red boxes were drawn by human hand.

Setting the parameters

To find the weeds, Mesgaran went to Google Street View, which hosts billions of panoramic photos. It didn't take long to find johnsongrass.

“The pictures are really good quality,” he said. “You can see plants and flowers.”

Street View's photos offer a 360-degree view, so in his request Mesgaran set parameters, based on street direction (bearing), to only see the side view. He also specified latitude and longitude, and other factors. To train the deep, or machine learning model, he chose Texas, where johnsongrass is prevalent.

A student sorted through over 20,000 images from that request to find pictures with johnsongrass and drew rectangular shapes around the weeds. They located 1,000 images.

The labeled photos were fed into a computer to train a deep learning algorithm capable of identifying johnsongrass in Google's images. The model was run again to capture potentially more images containing johnsongrass. These additional images were then labeled and used to further refine the model. With each iteration, the algorithm learned and became more accurate.

“This deep learning model was trained by these images,” Mesgaran said. “Once we had a semi-working model, we ran it against about 300,000 images.”

For Al-Khatib's request, researchers focused on 84,000 miles of main roads in California, Nevada, Oregon and Washington states. The team discovered 2,000 locations with johnsongrass.

Google Weed View cost less than $2,000 to purchase the images and teach the model. A traditional car survey to cover the same area would cost an estimated $40,000 in gas, hotel, food and other costs.

“In a matter of months, we came up with 2,000 records and I can do it for the whole U.S.,” Mesgaran said.

Next up? The entire United States.

This story was originally published on the UC Davis College of Agricultural and Environmental Sciences news site.

UCCE advisor Bruno guides, learns from dairies switching to milking robots

From left to right: Former UC Davis School of Veterinary Medicine researcher Fernanda Ferreira, Fred Rau Dairy manager Shonda Reid and UC Cooperative Extension dairy advisor Daniela Bruno have collaborated on studies of large dairies in California using automatic milking systems. A robot that pushes feed to the cows can be seen in the background. Photo courtesy of Daniela Bruno

Automatic milking systems increasingly used in California amid labor challenges

When third-generation dairy farmer Shonda Reid first saw a milking robot at a farm show 13 years ago, she immediately recognized that the technology represented the future. Her father, however, took a bit more convincing.

“I came home and showed him and said, ‘This is what we need to do.' And he thought I was kidding!” said Reid, dairy and farm manager for Fred Rau Dairy, which has a herd of 1,400 milk cows in Fresno County.

Years later, after the family had visited several dairies using automatic milking systems (AMS) across the U.S., they installed their first six robots in November 2021. By fall 2022, they had 24 robots, evenly split between two newly built “free stall” barns where the cows can freely go to the milking machines.

As Fred Rau Dairy was one of the first in California to implement AMS at such a scale, Reid and her team have been instrumental in growing practical knowledge on these systems. She also has been a valued partner to Daniela Bruno, University of California Cooperative Extension dairy advisor for Fresno, Madera and Kings counties.

Dairy farmers report that their cows appear to be calmer as they can voluntarily visit one of the milking robots, pictured here. The robot also provides real-time monitoring and data on the health and productivity of the herd and individual cows. Photo by Daniela Bruno

“Automatic milking robots are not a new technology, but it's new to California,” said Bruno, noting that the milking robots were first used on small, family-run farms in Europe, where the technology granted family members more time for rest and other pursuits.

To better understand the feasibility of milking robots for large dairies in California, Bruno – alongside former UC Davis School of Veterinary Medicine professor Fernanda Ferreira, University of Minnesota researcher Marcia Endres and other collaborators – began a project in 2020 to study the risks and opportunities of automated systems.

“The information is extremely useful for California producers to make informed decisions about implementing AMS on their facilities,” said Denise Mullinax, executive director of the California Dairy Research Foundation, which supported the effort through a competitive grant. “Cow care, labor requirements and profitability are key issues for producers, and CDRF was pleased to support this project which assists producers in understanding how AMS may impact those areas on their facility.”

Dairy farmer: ‘We needed to make some changes'

The project produced a paper analyzing existing research on automatic systems, which have been more widely used in the Midwest, where there are more small-scale, family-run dairies. In 2020, there were only 14 “box robots” in California, according to Bruno. Now there are about 200 across California – and both Bruno and Reid cited labor challenges as the primary reason for the increased use of automated systems.

“California suffers from labor quality and quantity issues,” Bruno said. “By bringing robots to California, you can minimize those problems.”

Higher costs of hiring and retaining employees, driven in part by new labor laws, are one factor. And then there's the reliability and availability of labor, as fewer people are willing to do the physically demanding work of conventional milking.

“People just don't want to milk in a flat barn [a conventional setup where the employee works at the same level as the cow] – there's a lot of kneeling, squatting, that type of thing – it's pretty tough on the body,” Reid explained.

UC Davis postdoctoral researcher Thaisa Marques, Fred Rau Dairy manager Shonda Reid, University of Minnesota professor Marcia Endres, UC Davis School of Veterinary Medicine professor Fabio Lima, UCCE dairy advisor Daniela Bruno and former UC Davis postdoctoral researcher Camila Lage stand in one of the free stall barns at Fred Rau Dairy. Two of the red milking robots can be seen in the background. Photo by Daniela Bruno

Faced with labor shortages and mounting regulatory burdens, Reid said Fred Rau Dairy had to make the leap to automated systems to keep the 80-year-old dairy operation running.

“We needed to make some changes, or we're going out of the dairy business,” she said.

In a survey conducted by Bruno and her colleagues of large dairies using AMS across the U.S., a majority of the 29 respondents reported reductions in labor costs – but survey results did not offer a definitive picture on whether AMS improved bottom-line profitability.

Calmer, healthier cows

Nevertheless, most of the survey respondents said they were generally happy with their transition to automatic systems.

“It's totally met our expectations, and cow health has gotten much better, too,” Reid said.

In a typical conventional system where cows are outside in “open corral” pens, dairy employees must cajole the cows into the milking parlor. But within a “free stall” barn where the cows can voluntarily go to the milking robots when they want, as often as they want, the animals are much less stressed.

“When you think about cow handling, if you have robots, you don't have anybody pushing and screaming at them to walk to the parlor,” Bruno explained. “You have less cow-people interaction so they are more calm; there is less stress.”

In the survey of large dairies using milking robots, more than 90% of the respondents said their cows were calmer. Reid also noted that many people have noticed how calm their cows are in the free stall barns.

“They're not skittish, you can walk in and they don't run,” Reid said. “They'll just watch you or they'll even come up and start licking on your jacket or shirt.”

About 60 dairy farmers, researchers and industry professionals toured Fred Rau Dairy and Jones Dairy as part of an Automatic Milking Systems Field Day in October 2022. Photo courtesy of Daniela Bruno

Bruno also said that many of the large dairies reported fewer cases of mastitis and other diseases, less lameness, and greater milk production. But she added it's hard to know whether the benefits can be attributed to the robots and their real-time monitoring technology – or to changes in the physical environment (cows save energy in the free stall barn setup, versus the open-corral system that requires walking to the milking parlor).

Dairy producers seek counsel on potential transition

Less bovine travel from outside to inside was a boon for Fred Rau Dairy during last year's unusually wet winter.

“Even if it's just a couple of weeks of rain, that mud and manure and everything – you do what you can, but oh my gosh – it's a mess,” said Reid, noting that easier facility maintenance during extreme weather was another benefit of switching to automatic systems within free stall barns.

Reid shared many of her experiences with attendees of an AMS Field Day in October 2022, arranged by Bruno, Ferreira and their collaborators. About 60 farmers, researchers, industry representatives and consultants visited Fred Rau Dairy and Jones Dairy in Merced County.

If a dairy producer is considering implementing automatic systems, Reid recommends that they research all their options, visit dairies that use the systems, and check who in their area would be providing service and technical support.

And there are crucial workforce considerations, as dairy workers must learn an entirely new set of skills and processes. Instead of spending their time fetching the cows, prepping them and milking them in the parlor, workers might need to gather and interpret data from the robots. “Cow people,” as Reid puts it, must become computer people.

“You have a group of people who have been with you for a while, and you hope that they can transition to the new technology of what you're doing,” Reid said.

During this technological transition, and on the myriad other challenges that dairy operators face, Reid said she is grateful for Bruno's expertise and responsiveness.

“If there's something that I need, she's been really good about trying to help – or putting me in contact with the right people,” she explained. “I've enjoyed working with her.”

The AMS project team also includes UC Davis School of Veterinary Medicine professor Fabio Lima, postdoctoral researcher Thaisa Marques and former postdoctoral researcher Camila Lage.

No-till annual wheat better for soil health in California’s climate

From left are researchers Mark Lundy, Kalyn Taylor and Taylor Becker, at the time all in the UC Davis Department of Plant Sciences, observing plots of wheatgrass. The photo was taken in 2019, during the second year of a three-year experiment to compare the benefits and disadvantages of perennial wheatgrass with tilled annual wheat and no-till annual wheat in California's Central Valley. Photo: UC Davis Department of Plant Sciences

One more reason to adopt sustainable cultivation

California wheat farmers could both maintain their yields and improve soil health by growing annual wheat without tilling the soil year after year.

This could be one more encouragement to farmers to adopt a sustainable practice commonly called conservation tillage, no-till or minimum-till cultivation, impacting how we grow a grain that supplies about 20 percent of the calories and protein for people around the world.

A new study, by a team led by Mark Lundy, University of California Cooperative Extension specialist in UC Davis' Department of Plant Sciences, offers new insight for decades-long discussions around soil conservation, sustainable agriculture and climate-warming emissions related to growing our food. The study has been published in the journal Soil and Tillage Research. For the first time, researchers have shown that annual wheat that is not tilled each year is better for stashing carbon in the soil than perennial wheatgrass, while still yielding more crop in Central California.

Previous studies have looked at annual wheat that is tilled each year, annual wheat that is not tilled, and a cousin species, perennial intermediate wheatgrass (trademarked Kernza), which also is not tilled. But until now, no one has looked at all of the benefits and trade-offs together. Most importantly, “no one has ever controlled for tillage,” Lundy said. “And, no one has compared annual wheat to perennial intermediate wheatgrass over multiple years in a Mediterranean climate, which is what we have in California.”

At the left is perennial intermediate wheatgrass (Kernza), and at the right is no-till annual wheat in experimental plots west of UC Davis in June 2019. Photo courtesy: Kalyn Taylor

This study also is unique because it delves into the deeper question of what is going on in the soil that drives the different results for carbon there. Soil carbon reflects various processes linked to plant activity and soil health. Measuring the different forms of soil carbon may also signal whether a farming system is accumulating carbon in the soil over time – a plus for reducing climate-warming gases in the atmosphere.

“Measuring soil carbon is complex and nuanced,” said Kalyn Taylor, the lead author on the paper. “We started this experiment because we wanted to know whether and how plant activity and tilling or not tilling would affect the carbon story belowground in California's climate.”

“When we started this study, we thought the crop being perennial or annual would drive the differences in carbon storage in the soil,” Lundy added. Specifically, they had expected perennial wheatgrass would lead to more carbon in the soil because of its deeper, better-established root system. “But that's not what we found,” he went on. “What we found was, it was the lack of tillage, plus the level of productivity of common annual wheat, that made the difference in soil carbon here in California.”

Soil carbon in annual vs. perennial grain

In 2017, Lundy, then-graduate-student Taylor, UC Davis Professor Emeritus Kate Scow and others on the team started measuring different forms of soil carbon in test plots at Russell Ranch, west of campus. Plots were planted with annual wheat that was tilled each spring, annual wheat that was not tilled and perennial intermediate wheatgrass (Kernza) that also was not tilled.

Each year, the researchers measured the carbon present in the soil, the amount of soil organisms (which have carbon in their bodies) and the amount of material the plants created.

At the experimental wheat field west of Davis in March 2019 are, from left: Kate Scow, of the UC Davis Department of Land, Air and Water Resources and co-principal investigator on the wheat study; Liz Carlisle, from UC Santa Barbara; Kalyn Taylor, of the UC Davis Department of Plant Sciences and lead author on the recent paper; and Bob Quinn, who earned a doctoral degree at UC Davis, then returned home to Montana to run the family's wheat farm. Photo by Daniel Rath

At the end of three growing seasons, they found that land planted with no-till, common, annual wheat had the highest amount of soil organisms, measured as biomass, of the three treatments.

The researchers also found soil carbon is more likely to remain stable in the no-till, annual plots, compared to both tilled wheat and wheatgrass.

In addition, the no-till, annual wheat produced plant material more consistently than the perennial wheatgrass across the three years, which saw variation in rainfall.

“Overall, annual wheat grown without soil disturbance or tillage had both higher productivity and higher potential for storing carbon in the topsoil than perennial wheatgrass in our Mediterranean climate,” Lundy said.

Related research

“No-till annual wheat increases plant productivity, soil microbial biomass, and soil carbon stabilization relative to intermediate wheatgrass in a Mediterranean climate,” is online now and will be published in the January 2024 edition of Soil and Tillage Research.

The team also found that tilled annual wheat vs. Kernza stores total carbon at different depths in the soil profile and hosts distinct soil fungal communities, primarily in the root zone and topsoil: Taylor, K., Samaddar, S., Schmidt, R., Lundy, M. and Scow, K., 2023. Soil carbon storage and compositional responses of soil microbial communities under perennial grain IWG vs. annual wheat. Soil Biology and Biochemistry, p.109111.

Previous work comparing the perennial grain known as intermediate wheatgrass (trademarked Kernza) to annual wheat had not distinguished the extent to which soil health benefits are a function of the perennial nature of the crop. Read the story here.

This story was originally published on the UC Davis News site.

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