Posts Tagged: Jeff Mitchell
Healthy soil does much more than hold plants upright on the surface of the earth. It is a mix of mineral bits and old plant particles teeming with microbes to form a mysterious and complex web of life scientists are just beginning to understand.
While scientists use high technology to study heathy soil – painstakingly counting soil worms and bugs, sequencing the DNA of soil bacteria, for example – some farmers know intuitively whether the soil is healthy just by walking on it.
Scott Park is a first-generation Meridian, Calif., farmer. “When I step on a field and it feels like a road, something is wrong,” he said. “If it feels like a marshmallow or sponge, that's good.”
Park shared his farming experiences with 200 farmers, industry representatives, University of California Cooperative Extension scientists, Fresno State students, news media and others during a half-day UC workshop at the UC West Side Research and Extension Center in Five Points.
“The last 31 years I've been on a mission of building soil,” Park said. “I discovered it by accident and I've made lots of mistakes. But yields trend upwards every year on every crop. Being sensitive to building soil, I'm making a lot of money. And if I'm doing something for the earth, all the better.”
Park said he adds 10 to 15 tons per acre of biomass to his farm every year. He's using less fertilizer, up to 20 percent less water, and even experimenting on the farm by growing a commercial crop with just four inputs: cover crops, water, seed and sun.
“We got high-yielding, good-quality crops,” Park said. “Nobody was more shocked than I am that I got a good crop.”
Researchers are now using the scientific method to figure out the root causes of these empirical observations.
“There's a lot going on in soil,” said Radomir Schmidt, a UC Davis soil microbiologist who spoke at the soil health field day.
A teaspoon of soil has a billion bacteria and six miles of fungal hyphae, the filaments that branch out through the soil from fungi, Schmidt said. The microbes' interaction with living plant roots, the larger pores left by decomposing vegetation and tunneling worms and insects create a system that confers resilience to unforeseen challenges – such as pest pressure, torrential rainfall and plant diseases.
The field day was held under a tent pitched adjacent to an 18-year research trial at the 320-acre facility. The trial compares four farming systems side by side:
- Conventional system, with annual soil tillage and no cover crops.
- Conservation agriculture, with no tilling whatsoever and annual winter cover crops.
- No-till without the cover crop.
- Conventional tilling with a cover crop.
“Take a look over my shoulder to see the difference,” said Jeff Mitchell, UC Cooperative Extension specialist and the study leader. “We've found the cover crops and no-till reduce water needs, cut dust, and lower costs. And there may be more benefits than we realized.”
For example, a graduate student counted the worms, bugs, beetles and other microfauna in soil samples from each of the treatments. There were double the amount in the no-till, cover crop plots compared to the conventional farming system.
UC Cooperative Extension specialist Sloan Rice found that cover crops promote water retention in the soil after rainfall. There is very little water evaporation from the soil surface and water transportation from the cover crop plants in the winter, so little water is lost. Cover crops also promote more water infiltration below three feet.
Healthy soil management also shows promise in confronting global climate change by sequestering carbon in the soil, rather than depleting it.
Manager of Sano Farms in Firebaugh, Jesse Sanchez, was a speaker at the field day. He wasn't surprised by the overflow crowd.
“Farmers are more and more curious. They see some of us using cover crops, and they want to learn more,” Sanchez said. “There has been a swell of interest. I have a tremendous number of visitors every year.”
For more information about soil building, see the UC Conservation Agriculture Systems Innovation website at http://casi.ucanr.edu.
How do you cut your water use by a third, cut your nitrogen use in half, maintain your tomato yield and improve your fruit quality?
“With patience, perseverance and by treating your soil like a living ecosystem — which it is,” says Jesse Sanchez.
Sanchez should know. He and Alan Sano have been experimenting with soil enhancements for 15 years on Sano Farms in Firebaugh. They believe they have hit upon a winning strategy — though their experiments continue.
Today, they grow 50-ton-per-acre tomatoes with half of the nitrogen (120 units) and a third less water than before. They also report fewer weeds and better tomato quality.
The soil organic matter (SOM) — the living portion of the soil that turns crop residue into minerals needed by growing plants — has gone from 0.5 percent to 3.0 percent, report Sano and Sanchez.
“The soil is like day and night,” says Sanchez. “You can dig it with your hands,” he says, cupping a handful to prove his point.
So how do you transition largely inert soil into the ecological powerhouse found on Sano Farms?
Cover crops, reduced equipment passes, and subsurface irrigation have been key, according to Jeff Mitchell, UC Cooperative Extension specialist based at the UC Kearney Agricultural Research and Extension Center. These practices combine to feed and protect the soil microorganisms often ignored in agricultural systems. Mitchell has been coaching the Sano/Sanchez team for over 10 years, witnessing their progress and connecting them with like-minded farmers and organizations.
“Farmers sometimes worry that cover crops will compete with the cash crop for water and nutrients,” says Mitchell. “We're starting to see at Sano Farms — looking long term — that the tradeoffs might actually be favorable.”
Sanchez says he terminates the cover crop before the tomatoes are planted, leaving the dead residue to smother weeds and feed the soil microorganisms.
The SOM also builds the sponge that allows the farm to thrive on less water, says Zahangir Kabir, soil health specialist with USDA's Natural Resources Conservation Service.
“A one percent increase in SOM builds your soil's ability to hold water by 19,000 to 25,000 gallons per acre. Calculating conservatively, Sano Farms' fields hold 50,000 gallons of water more per acre than they did before," Kabir said.
You can see this in action at Sano farms. “When it rains here the water soaks into the field. It stays put,” says Sanchez. “It doesn't run off like some farms.”
Sanchez, who received a White House Champions of Change Award last summer, says he knows farmers resist change. “But we can't stop change,” he says. “It's all around us.”
And, if they (farmers) do change the way they work with their soil, says Sanchez, “they are going to like what they see. ”
Sanchez will be a featured speaker at the second annual Latino Farmers Conference on Nov. 15 at the Monterey Hyatt Regency. The event is free but registration is required. http://www.nrcs.usda.gov/wps/portal/nrcs/events/ca/newsroom/events/?eventid=584#584 .
USDA NRCS produced a three-minute video profile of Alan Sano and Jesse Sanchez at Sano Farms in Firebaugh. View it here:
Jeff Mitchell, UC Cooperative Extension agronomy specialist.
A series of farm visits this summer in the Central Valley prove this rationale wrong, Mitchell said. The farm visits were sponsored by the UC Conservation Agriculture Systems Innovation Center (CASI), USDA's Natural Resources Conservation Service and the California Association of Resource Conservation Districts. The farm visits showcased the soil health goals and experiences of six farmers who are familiar with soil care principles across a wide range of local cropping contexts.
The series of visits demonstrated the use of no-till and minimum tillage farming, cover cropping, enhancing the diversity of above-ground species and underground soil biology, surface residue preservation, and compost applications.
John Teixeira is a diversified farmer in Firebaugh working to develop integrated crop and livestock systems that are not reliant on external inputs. Pursuing a diverse rotation that includes alfalfa, cover crops, and a variety of heirloom grain crops that are marketed as both raw seed and value-added pasta, Teixeira is working to enhance soil function and fertility so that all external impacts are eliminated.
Michael Crowell and his son Adam grow silage crops near their Turlock dairy and dryland small grain crops using no tillage along Highway 4 in the rolling hills south of Dixon. They use no-till as a means to reduce soil water evaporation and to increase the water holding capacity of their soil, thereby enabling them to produce economically viable crops on the region's typical 14 inches of winter rainfall.
Darrell Cordova and his son Trevor of Denair also use no-tillage for their summer silage corn and winter small grain forage mixes and as a means for stabilizing the soil, adding surface residues, increasing infiltration and reducing runoff under their center pivot-irrigated crops growing on undulating terrain. These practices also cut costs and eliminate considerable labor.
Tom Willey of Madera uses compost applications ahead of each of his organic vegetable crops to build the nutrient-provision and water-holding capacities of his soils. His sustained dedication to these amendment applications and his farming goal of attempting to mimic natural systems in terms of active, high-functioning soil biology enable him to produce a great diversity of very high quality vegetables.
Alan Sano and Jesse Sanchez in Firebaugh have combined the conservation ag/soil care practices of reduced disturbance and cover crops for more than 10 years in their processing tomato fields. They report lower costs, improved soil tilth, and the ability to reduce nitrogen fertilizer inputs by about half.
“These six soil care farmers share an uncommon dedication to the principles that are at the core of soil health and conservation agriculture systems,” Mitchell said. “Each of them reported tangible value that they are receiving from their attention to caring for the soil and working to improve soil function.”
Mitchell and the network of organizations that are part of CASI now seek a new wave of farmers who are interested in evaluating conservation agriculture, climate-smart practices at their farms.
For information on how to become involved with farm performance monitoring and the educational activities, see the CASI website at http://casi.ucanr.edu/
That is beginning to change.
UC Cooperative Extension and Fresno State agricultural production scientists researched overhead irrigation at the UC West Side Research and Extension Center for five years, growing wheat, corn, cotton, tomato, onion and broccoli and comparing them with crops produced under furrow and drip irrigation. With all of them except tomato, overhead irrigation led to similar or increased yields, according to the scientists' report published in the current issue of California Agriculture journal.
“Overall, we are very encouraged by these results, and they reflect the experiences that many California farmers have recently been having with overhead irrigation systems,” said lead author Jeff Mitchell, UC Cooperative Extension specialist. “We've confirmed that overhead irrigation systems work in California. We also concluded that there are opportunities to get even better results with more research and experience, particularly when overhead irrigation is coupled with practices that preserve crop residues and rely on reduced tillage.”
The tomato yields under overhead irrigation were disappointing, particularly since tomatoes have a prominent role in many Central Valley annual crop rotations.
“This isn't a simple process,” Mitchell said. “You can't just turn it on and let it go. It will require focused and dedicated farmer and researcher attention and innovation to solve.”
The authors are working with a team of Central Valley tomato farmers, processors, irrigation experts and research colleagues to improve overhead irrigation management in tomatoes. They are encouraged by the success of Walnut Grove farmer Michael Boparai, who achieved profitable processing tomato yields with overhead irrigation.
Overhead irrigation systems were invented more than 60 years ago. They now irrigate 50 percent of total U.S. farm irrigated acreage. In Nebraska, 87 percent of irrigated land is under overhead systems. By contrast, in California overhead systems irrigate only 150,000 acres, just 2 percent of the state's irrigated farmland.
Mitchell and his co-authors outlined several factors that contributed to its slow rate of adoption in California:
- Early adopters ran into serious problems, giving the systems an undeserved bad reputation that persists even though in recent years California farmers are using the systems successfully.
- Center pivot systems typically leave the corners of the field unirrigated, which can reduce production.
- Purchase and installation cost of the overhead system is substantially higher than furrow irrigation.
However, the UC and Fresno State research has shown many advantages.
- Overhead irrigation can be managed remotely and automatically.
- The system can accommodate different terrain and soil types.
- Overhead systems requires less maintenance than drip systems in terms of avoiding clogging of emitters and repairing leaks.
- Overhead irrigation may also help with salinity management by uniformly leaching salts from a crop's root zone.
- Precision irrigation, including overhead systems, are becoming ever more critical with coming groundwater regulations, surface water cuts and the increasing cost of water for farmers in California.
A significant advantage of overhead irrigation is its compatibility with other farm management technologies that optimize the farming system and reduce costly inputs, including water, fuel, labor and fertilizer.
“We're committed to continuing our work on the whole package – reduced tillage, preserving residue, improving water infiltration, improving soil water-holding capacity and increasing productivity uniformity – a system that we refer to as conservation agriculture,” Mitchell said. “We are working to encourage adoption of conservation agriculture in crops where viability of the system is well established, and facilitate the research and innovation needed to optimize conservation agriculture production in additional crops.”
Jeffrey Mitchell of UC Agriculture and Natural Resources (UC ANR).
“The soil-water interaction under various soil management practices will be quite clear if we do get the increased rainfall this winter that has been forecast,” Mitchell said. “Soil high in organic matter and covered by plant residue will allow increased water infiltration and storage, less water runoff and, on a large scale, increased groundwater recharge.”
Mitchell, a UC ANR Cooperative Extension specialist based at the UC Kearney Agricultural Research and Extension Center, has researched conservation agricultural practices for nearly 20 years. He is chair of UC ANR's Conservation Agriculture Systems Innovation Center (CASI), a collaborative organization involving researchers, farmers and industry partners who aim to increase the use of conservation practices in California.
Most farmers in the San Joaquin Valley till their land after harvesting row crops believing they have to create clean planting beds for seeding and establishment of subsequent crops. The practice, Mitchell said, is influenced mainly by tradition.
Research at the UC West Side Research and Extension Center that has been ongoing since 1999 has documented striking changes in plots after sustained cover cropping and no-till management. In addition to improved soil properties, the plots managed with conservation agriculture practices have comparable or in some cases higher yields, less soil water evaporation, lower dust emissions and, because of the higher soil organic matter, sequestered more carbon than adjacent plots managed using conventional practices.
In other parts of the world, generating and preserving plant residues are an indispensable part of farm management. Increasingly in California, farmers are implementing conservation tillage practices.
In addition to protecting soil from driving rain and wind in the winter, the plant residues provide important benefits in the summer. The plant residue on the surface shades the soil, providing a beneficial cooling effect, and soil with high organic content has higher moisture holding capacity.
“A number of studies from both irrigated and rain-fed regions around the United States where no-tillage is used have reported annual irrigation savings of as much as four to five inches,” Mitchell said.
Good soil management also promotes its biological diversity, noted Randal Southard, a CASI member and professor in the Department of Land, Air and Water Resources at UC Davis.
“Reducing soil disturbance, keeping the soil covered with plant residues and promoting high biological diversity provide soils with resilience – the ability of soils to accommodate changes in a wide array of environmental conditions,” Southard said. “Soil resilience or soil health is similar to how we think of human health, including overall well-being and the ability to resist diseases and other maladies.”
Soil is getting increasing attention in California and worldwide. The United Nations declared 2015 the International Year of Soils to raise awareness about a substance that is the very foundation of life on earth. The USDA's Natural Resources Conservation Service launched a Soil Health Campaign and the California Department of Food and Agriculture has created a Healthy Soils Initiative.
A network of soil health demonstration evaluations is now being created by CASI in California. Local teams are being organized in Sacramento, Mendocino, Stanislaus, Fresno and Kern counties involving Resource Conservation Districts, USDA Natural Resources Conservation Service and UC ANR Cooperative Extension researchers and local farmers. The farmers will set aside small comparison plots to evaluate practices that are believed to improve soil health and the researchers will have a role in monitoring and documenting changes.
“Each of these efforts points to the pivotal role healthy soils have in food security, agricultural sustainability and climate change resiliency,” Mitchell said.
Author: Jeannette Warnert