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No-till annual wheat better for soil health in California’s climate
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.”
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 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.
Bees Buzzing on Breathtakingly Beautiful Berry Blossoms
The alliteration doesn't get much better--bees buzzing on breathtaking berry blossoms. Berry...
Two honey bees foraging on berry blossoms at the UC Davis Ecological Garden at the Student Farm. (Photo by Kathy Keatley Garvey)
A honey bee and a native bee seeking the nectar at the base of the berry blossoms. (Photo by Kathy Keatley Garvey)
A honey bee nectaring on a berry blossom. (Photo by Kathy Keatley Garvey)
A honey bee takes flight--time to head for another berry blossom. (Photo by Kathy Keatley Garvey)
Meyer receives Bradford-Rominger Agricultural Sustainability Leadership Award
Deanne Meyer, UC Cooperative Extension livestock waste management specialist, is this year's recipient of the Eric Bradford & Charlie Rominger Agricultural Sustainability Leadership Award, given by the Agricultural Sustainability Institute (ASI) at UC Davis.
Meyer is being honored for her leadership in substantially improving the sustainability of California's dairy industry through her research and outreach.
The Bradford-Rominger award recognizes and honors individuals who exhibit the leadership, work ethic and integrity epitomized by the late Eric Bradford, a livestock geneticist who gave 50 years of service to UC Davis, and the late Charlie Rominger, a fifth-generation Yolo County farmer and land preservationist.
Meyer has directed the environmental stewardship efforts of the California Dairy Quality Assurance Program (CDQAP)—a voluntary partnership between the dairy industry, government and academia—since the program's inception in 1996.
Meyer's dedication to build a bridge between industry and regulatory agencies has paid dividends for California's air and water quality. With Meyer's leadership, more than 700 dairy farms have completed an on-site, third-party evaluation of their facility's manure management. The program has been so successful that it received California's highest environmental honor, the Governor's Environmental and Economic Leadership Award, in 2007.
Reflecting on Meyer's work, Glenda Humiston, UC vice president for agriculture and natural resources, said, “Serving as chair of California's Water Quality Task Force in the mid-1990s, I had a front row seat to the challenges Deanne faced as she organized CDQAP and brought many unlikely allies to the table. The many successes of that program is a testament to her skills as both a scientist and a diplomat.”
Beyond Meyer's work with CDQAP, her research in groundwater salinity has provided farmers, agency staff and other concerned stakeholders with unbiased information presented with an understanding of agricultural realities.
“Her efforts, leadership, and dedication are so valued by all the diverse sectors she works across,” said Anita Oberbauer, professor and dean for Agricultural Sciences at UC Davis. “By working closely with regulatory agencies and farmers, she ensures our state's livestock and dairy producers have the tools that they need to meet the environmental challenges.”
Learn more about the Bradford-Rominger award on the Agricultural Sustainability Institute's website.
Past winners of the Bradford-Rominger award include UC Cooperative Extension advisors Rachael Long, Rachel Surls and David Lewis, Sustainable Conservation's Director of Resources Daniel Mountjoy; UCCE advisor Rose Hayden-Smith, UCCE specialist Ken Tate, UCCE advisor Mary Bianchi, natural resource conservation consultant Kelly Garbach and UC Davis lecturer emeritus Isao Fujimoto.
vineyard weed control podcast link
A quick link to a Vineyard Team podcast and workshop series on weed control in California winegrape...
A nutty idea: A little stress could be good for walnuts
When it comes to watering walnuts, most California growers believe you need to start early to keep trees healthy and productive throughout the long, hot summer. But according to striking results from a long-term experiment in a walnut orchard in Red Bluff, growers can improve crop production if they hold off irrigation until later in the season and directly measure their trees' water needs.
The findings from researchers at the University of California may help farmers optimize water use.
“It's a game-changer,” said walnut grower Hal Crain, who welcomed researchers on to his orchard to test irrigation optimization. “It's clear to me you can improve nut quality and yield by applying water based on what the tree wants and needs, rather than just watering when it's hot outside and the soil is dry. That's a big deal for walnut growers and for the entire agricultural industry.”
Changing the paradigm
Crain is a second-generation farmer whose family has been growing walnuts in Butte and Tehama counties for 55 years. Like most walnut farmers, Crain had always started irrigating in early to mid-May when the days grew warmer and the trees sprouted leaves.
“That's standard practice for probably 90 percent of California's walnut growers,” said Crain, walking amid his trees on a sunny afternoon. “The theory is that when you irrigate early, you preserve the deep moisture in the soil that trees need to survive the heat of summer.”
But that's not how it works, the research shows. Instead, trees that grow in saturated soil early in the season don't develop the deep roots they need to thrive.
“With all the water right there at the surface, the lower roots suffer,” explained Bruce Lampinen, UC Cooperative Extension orchard management specialist with the UC Davis Department of Plant Sciences. “Trees end up with a very shallow root system, which doesn't serve them well as they try to extract moisture from the soil later on.”
Lampinen has long suspected that walnuts were getting too much water in the spring.
“A lot of the symptoms we see like yellowing leaves and various diseases can all be explained by overwatering,” said Lampinen.
So Lampinen did what scientists do: He set up an experiment. Five years ago, with funding from the California Walnut Board and the U.S. Department of Agriculture, he joined forces with Ken Shackel, a plant sciences professor with UC Davis, and Allan Fulton, an irrigation adviser with UC Cooperative Extension. Together, they led a team of scientists testing irrigation on Crain's ranch.
“Hal is an exceptional partner,” Fulton said. “Farmers have a lot to accommodate when they host an experiment like this, with researchers going in and out of the orchard at all hours. He had to work around our people and the timing of our water treatments. He's always eager to experiment with technology and learn new things, and he shares what he learns with other growers. Hal completes the circle.”
Tough nut to crack
When is the best time to irrigate? Researchers say the trees hold the answer. Scientists use pressure chambers, which are air-pressure devices that measure a leaf or small shoot to gauge how hard the plant is working to pull moisture from the soil.
“Just because the soil looks dry doesn't mean the plant is suffering,” said Shackel, who specializes in plant physiology. “Pressure chambers let you ask the tree how it's feeling — sort of like taking a human's blood pressure — which is a much more accurate way to measure a plant's water needs.”
For the last five years, the team has been applying different water treatments to five blocks of trees. One block is getting standard, early irrigation. Crain's orchard managers begin irrigating the other blocks when the trees reach different levels of water stress based on pressure-chamber readings.
The trees that experience moderate stress are doing the best. Their irrigation usually starts in mid-to-late June, several weeks later than when standard watering begins.
“You can tell just by looking at that block that the trees are healthier,” said Crain, standing beneath a canopy of lush, green trees. “And, we're starting to see greater yields and better nut quality.”
Translating the research
The research is helping scientists advise farmers on irrigation.
“My biggest take-away is knowing when to start watering is a really important factor to the health of your trees,” Lampinen says.
Pressure chambers — sometimes called pressure bombs — can cost more than $3,000, and high-tech versions are under development.
“I tell growers a pressure bomb would pay for itself even if you just used it once a year to determine when to start watering,” Lampinen said.
Crain is certainly convinced.
“When you irrigate based on your trees' needs, you optimize water,” Crain says. “I'm not using less water overall, but the water I do use is producing more food. That's good news for everyone.”
This story was originally published in the Fall 2018 issue of Outlook Magazine, the alumni magazine for the UC Davis College of Agricultural and Environmental Sciences.
