Posts Tagged: soil health
Historically, chickens were not a rare sight on farms, where they contributed to soil fertility as they freely pecked and scratched around vegetable gardens and crop land. Now, UC Cooperative Extension specialists have launched a research project to quantify the potential for chickens to be part of safe and sustainable commercial organic vegetable production.
“It's not a new idea. A lot of farmers are trying this kind of thing,” said UC Davis International Agriculture and Development graduate student Faye Duan, the project coordinator. “But there is currently little scientific information for using chickens on a bigger scale, especially in terms of food safety concerns.”
The California trial is part of a national effort to diversify organic vegetable farms with chickens. Last year, the USDA-funded study was launched by Iowa State University horticulture professor Ajay Nair. The project also includes UC Cooperative Extension specialists Maurice Pitesky and Jeff Mitchell, based at UC Davis, and University of Kentucky entomology professor David Gonthier.
In the trials, chickens are introduced as part of a rotation that includes cover crops and a variety of vegetable crops. In California, chickens were placed on research plots in April following a winter cover crop of vetch, peas, fava beans and oat grass.
“We don't let the chickens run around the field,” Duan said. “We keep them inside of chicken tractors to protect them from predators.”
Twenty-nine birds live in each 50-square-foot tractor, essentially a floorless chicken coop on wheels. The tractors, built by UC Davis students Mallory Phillips and Trevor Krivens, are wood frames covered with mesh and plywood. Each day, the tractors are moved to a different part of the plot, where the birds can graze on cover crop residue and deposit manure. Adjusting to the daily move took time, Duan said.
“The first day, the chickens were confused. We had to go slowly. It's a learning process for the chickens and us,” she said. “But now, the chickens are excited to move to a new spot where they have fresh food to graze on.”
After 24 days on pasture, the chickens will be removed, and become part of the project's meat study.
“We have broiler chickens that are raised for meat,” Duan said. “Some people believe chickens that graze and eat grass taste better and are more nutritious. It will be part of the study to look at the chicken's meat quality.”
Once the chickens have done their part on the research plots, vegetables are planted amid the leftover cover crop residue and chicken manure. This summer, the experiment in California will grow processing tomatoes. Subsequently, melons, eggplant, spinach and broccoli will be part of the vegetable rotation in California or the other states involved in the project. Other replications of the trial will have the chickens immediately follow the vegetable harvest so they can graze on the crop leftovers before the cover crop is planted. Comparing the soil health, fertilizer needs, chicken quality and other factors will help the scientists optimize the rotation.
“Vegetable yield will be an important indicator of success,” Duan said.
Soil samples will be tested to determine the presence or absence of Salmonella bacteria after the chickens have been removed, said Pitesky, a poultry specialist and a project lead. Salmonella is a bacterium that can be part of poultry's microbiome. If the bacteria contaminates human food, it can cause illness.
“Since Salmonella lives in the chicken gastrointestinal system, when it gets into the soil, it will eventually be out-competed by bacteria more adapted to soil than the gut of a chicken,” Pitesky said. “There are many different types of Salmonella, and only a select few found in birds are the ones that are harmful to humans. Nevertheless, it is very important to test and use various practices to mitigate the presence of Salmonella on land that will be used for crop production following poultry.”
Early results of soil tests in Iowa and Kentucky detected Salmonella in the soil where chickens grazed, however, the bacteria disappeared very quickly.
University of California Cooperative Extension and the Colusa County Resource Conservation District announce the launch of the Soil Health Connection, an informative outreach YouTube channel. The channel hosts virtual discussions and interviews with leading soil science researchers and farmers with the intention of shedding light on the importance of soil health in California's agricultural systems.
Hosts Sarah Light, UCCE agronomy advisor, and Liz Harper, Colusa County RCD executive director, bring their own knowledge and expertise to the channel by inviting guests and viewers to think about soil health through various lenses. The channel has already released episodes touching on the connections between soils and economics, agroecology, nutrient management, conservation, regenerative agriculture and more.
Featured guests from a multitude of backgrounds help capture differing perspectives and the interdisciplinary nature of the field of soil health. One episode in Spanish has been released.
Soil Health Connection is a product of Light and Harper's collaborative research supported by the California Department of Food and Agriculture Healthy Soils Program in partnership with Richter AG and Davis Ranch. The project is evaluating how soil moisture dynamics change with and without cover crops in an annual cropping system. In addition to the applied research and demonstration aspect, the project also aims to provide a platform for community outreach and education.
Experts in soil health and related fields, as well as growers participating in soil health practices, are encouraged to email Light at email@example.com if interested in participating in the Soil Health Connection.
To learn more about soil health in the Sacramento Valley, tune in to hear from the professionals who are getting their hands dirty with these issues every day. New episodes are released bi-weekly at https://www.youtube.com/channel/UCRI4lXL4f_ro_Flnp4lu6IA.
Powers of microbes: UC Davis graduate students get creative to teach farmers about soil microbiology
If you grew up in the 1980s or 1990s (or were a child at heart during that era), the famous Powers of Ten film likely left an indelible mark in your mind.
The film starts with a couple lounging on a picnic blanket and zooms out to the outer reaches of the universe, then back in to peer into the microscopic world of the human body: from white blood cells to DNA, and finally down to the proton of a carbon atom.
In its short 9-minute run time, Powers of Ten manages to inflame an existential angst about the size of a single human life while at the same time connecting the viewer to the beauty of the universe and the human body.
As a high school student watching the video, it filled me with the same sense of awe that I felt the first time I heard Carl Sagan's famous quote that “we are all made of star stuff.”
Powers of Ten reminds us that looking at the world from different perspectives, from the very tiny to the immensely large, helps create a better understanding of the natural world, our place within it, and how we can impact it for good.
Had Powers of Ten returned from outer space by zooming into a piece of soil rather than a the human body, it would have explored the billions of living creatures in one handful of soil, slowly scaling down from millipedes to earthworms to ants to nematodes to protozoa, and finally down to the soil's bacteria and fungi that make up the base of the soil food web.
The video might then have looked a lot like the recent workshop at the Russell Ranch Sustainable Agriculture Facility, which served as a science fair for farmers and researchers to learn about the minuscule but powerful soil microbe.
While farmers often have a baseline knowledge about soil microbiology and its importance on the farm, “the science is evolving so quickly at this point, that it can be hard to keep up,” said attendee Margaret Lloyd, UC Cooperative Extension advisor who works with small-scale farmers in Yolo and Sacramento counties.
The workshop coupled foundational principles of soil microbiology with practical on-farm management situations, making the case for farmers to actively consider soil bacteria, fungi, and other micro organisms in their decision-making process.
Jessica Chiartas, a fourth-year graduate student in soil microbiology and one of the workshop organizers, is somewhat of a soil science evangelist.
Her hope was to help workshop attendees better understand that “soils are not just physical, chemical systems. A majority of the processes that take place underfoot are biologically driven. Soils are living and breathing bodies and much like us, they need to be fed, covered, and protected from disturbance” in order to function in the long term.
The scale of microbial activity in soil makes it challenging to help farmers dig into just what scientists are talking about when they talk about microbes.
“It's important to talk about the scale of microbes,” Chiartas said. “So much of what goes on in soils is mediated by microbes and the scale that they operate on is far different than the scale we measure them at. Our typical method of soil sampling and analysis is analogous to harvesting whole fields of crops, chopping them up, throwing them in a heap and then trying to glean information about the individual plants.”
The presenters at the soil health workshop used vivid analogies to translate the abstract results of scientific research and hard-to-imagine scales into concrete, relatable concepts.
A single gram of soil may contain a billion bacteria, and several miles of fungal hyphae, the web-like growth of fungus. Translated into human scale, the numbers are mind boggling.
If a single microbe were a 6-foot-tall person, then a single millimeter of soil would be as tall as the empire state building. A typical soil bacterium contains as many DNA letters in its chromosome as two copies of “War and Peace.” A stack of copies of “War and Peace” equivalent to bacterial DNA from a single teaspoon of soil would be larger than the Great Pyramid of Giza.
A soil information revolution
The metaphors of scale are a fun thought experiment, and they could provide a jumping-off point for a discussion between farmers and scientists essential for improving our current understanding of soil as a living system. Climate change is expected to amplify the effects of soil erosion, compaction, nutrient leaching and other issues common in our current agricultural systems.
“We need improved management that works with the soil ecosystem to increase crop production while enhancing soil health,” said Radomir Schmidt, a postdoctoral researcher and workshop organizer. ”That's going to take a concerted effort and open dialog between farmers, scientists, and citizen scientists to discover, test, and implement these methods in the real world.”
We are now in the era of “soil information revolution," Schmidt said. As our knowledge of the soil microbiome expands, implementing this knowledge in agricultural practice is more and more possible.
This graduate student cohort is well-positioned to make the necessary connections, learning from farmers while helping them zoom in to see the essential lifeforms that impact their farm, then zoom out to help make decisions that are good for the farmer, good for the crop, and good for the microbe.
Farmers in the Davis area will have another opportunity to learn soil health fundamentals at a workshop this fall hosted by the UC Sustainable Agriculture Research and Education Program and Russell Ranch Sustainable Agriculture Facility. Details about the workshop will be posted here.
The numbers are beginning to trickle in confirming UC Cooperative Extension advisor Brent Holtz' hunch. Chipping and returning expired almond orchards into the soil where they grew is not only environmentally sound, it is economically smart.
(View a three-minute video of the machinery in action at the end of this post.)
After about 20 years, almond orchards' productivity and vigor begin to decline. Most farmers remove the old trees and plant younger, more vigorous replacements to keep up almond production.
In the past, old trees were easily and cheaply disposed of: they were pushed into a pile and set on fire. Air quality regulations have all but eliminated the practice.
At first, grinding the trees and sending the chips to a co-generation plant was a farmer's preferred option. The companies that used biomass for electricity generation paid an acceptable sum – about $600 per acre – for the wood chips, which helped offset the cost of chipping and hauling the trees off the property.
However today, electrical utilities are looking for clean, renewable energy sources like wind and solar.
“Cogeneration plants burn wood biomass, which still releases carbon dioxide and methane into the atmosphere,” Holtz said. “Many are losing contracts and shutting down.”
Holtz sought another cost-effective alternative, and believes incorporating the wood into the orchard floor may be the answer. Although initially expensive, adding $400 per acre to the $600-per-acre cost of chipping the old trees, the organic matter and nutrients released by the woodchips over time appear to boost yield to a level that covers a chunk of the cost.
In preliminary research, Holtz found that almond orchards where old wood was incorporated into the soil were averaging about 1,800 pounds of meat nuts per acre, while the orchard where old trees had been burned averaged 1,600 meat nuts per acre.
“Almonds sell for about $2 to $3 per pound. To have a 200-pound average yield increase per acre, you've made up the cost of incorporating the wood in just one year,” Holtz said. “It would be even more affordable if farmers can sell carbon credits for the biomass that they sequester in the ground.”
Holtz recently demonstrated two approaches for incorporating almond trees into the soil. The first, which was also used in the study eight years ago at the UC Kearney Agricultural Research and Extension Center in Parlier, is a 50-ton rock crusher called the Iron Wolf. It lumbers down the tree row, grinding up whole trees in place, then reverses over the mangled wood to incorporate it into the ground.
“We thought this one-machine process was the answer,” Holtz said.
G & F Ag Services in Ripon, which has made a business of chipping and hauling almond wood to a co-generation plant, conceived another plan. It modified a manure spreader to spray ground-up wood chips across the orchard floor. Holtz worked with Manteca farmer Louie Tallerico to give the new process a spin.
“This required five different machines working together compared to one Iron Wolf. In this process, the trees have to be excavated by an excavator, then hauled to the wood chipper with a front-end loader. The trees have to be fed into the wood chipper, then the wood chips have to be spread on the orchard floor,” Holtz said. “Another machine, a disk or roto tiller, incorporates the chips into the soil.
The five machines combined are a tremendous time saver.
“The Iron Wolf could do about two acres per day,” Holtz said. “This process can do 15 or 20 acres per day.”
Tallerico opened his farm for a field day in October to demonstrate parts of the process to other farmers and industry representatives. Participants stood on layer of fresh-cut wood chip mulch where a full-grown almond orchard stood just weeks before. The spreader demonstrated the ease with which the wood chips are dispersed evenly across the orchard floor, and a tiller mixed the wood chips into the soil.
The Tellarico orchard will now be the site of research – funded by the California Almond Board – to be conducted by Holtz and a team of scientists interested in documenting the growth and development of the new almond orchard among the remnants of its predecessor.
“In the previous study, three years after incorporating the old trees into the soil we started to see the nutrient benefit,” Holtz said. “This was done at Kearney, where we incorporated a peach orchard that had about 30 tons of organic matter per acre. Almond trees are larger, so here we have 86 tons of organic matter being returned to the soil.”
In the new study, the scientists will determine whether the nutrient benefits found in early research still hold true, whether the wood chips in the soil stunt the new orchard or boost its growth, whether the new orchard suffers from replant disease, and the fate of good and bad nematodes (tiny soil-borne worms) in the new orchard.
“We will also study the carbon budget and continue the life cycle assessment of almond with this practice, to better understand the benefit of these processes,” Holtz said.
For many years, a key international strategy to ending hunger has been to grow more food: push for higher yields, develop ways for farmers to intensify their farming, focus on technologies that drive both. But that focus may be shifting towards another strategy that better accounts for the environment and human well-being – agroecology.
Barbara Gemill-Herren, a retired officer from the Food and Agriculture Organization of the United Nations, spoke recently at UC Davis of the ongoing process at the United Nations to determine an international strategy for agricultural development.
For many, a new paradigm needs to strike a balance between supporting small-scale farmers, supporting healthy ecosystems, and bringing in the technology that can help meet changing challenges for growers.
Agroecology has recently entered the vocabulary at the UN as a potential unifying principle for agricultural development.
As its name suggests, agroecology studies the ecology of the entire food system, focusing on environmental, economic and social dimensions and how they interact with one another.
Beyond that definition, the term is used and understood differently by different groups. For some, agroecology is a scientific discipline, for some it represents a way for farms to be managed. For others, it is a social movement that brings local and indigenous knowledge to the center of agricultural development.
At the United Nations meetings on agroecology, each of these interpretations of agroecology have been on the table for discussion — how they can be used to improve international agricultural development will be revealed in global conversations in the years to come.
Agroecology endowment at UC Davis secures research opportunities
Here at home, agroecology is on the upswing as well. Funding for a $1 million endowment in agroecology was recently secured at UC Davis to help fund the research, education, and outreach conducted by an agroecology faculty member. Collaborating with UC Cooperative Extension farm advisors from UC Agriculture and Natural Resources will be a key way for future work to connect with growers.
Endowments offer reliable funding every year that allow faculty to plan longer term research. For research like agroecology that looks at how agricultural systems function, that flexibility is important, if not essential.
Tom Tomich, director of the Agricultural Sustainability Institute, which helped raise funds for the endowment, says, “The endowment represents at a broad spectrum of philanthropists and shows that scientific approaches to agroecological systems science is appreciated by our stakeholders in California. It's a form of legitimization of systems science applied to agriculture.”
Opportunities for collaboration between researchers and farmers
Below are some thoughts from Gaudin on how she approaches her work and how she sees this agroecology endowment impacting research and education at UC Davis.
How do you define agroecology?
There are different definitions of agroecology for different people. Mostly I see it as research to understand dynamics of ecological processes and to apply ecology to agricultural systems design. Agroecology merges the food security and production goals of agriculture with resource use efficiency goals and environmental goals in agriculture. For many people, agroecology is a social movement to make systems socially just. While my focus is largely on biological processes, it's also about learning from small-scale farmers who have been successful in their management practices to see how we can translate those successes to other contexts. And that is very social in nature.
At what scale do you research?
Usually we tend to work at the field scale, looking at cropping systems and the landscapes that surround them. Looking at the field, we can see how the long term management of a farm has affected the soil and its functioning as well as productivity and provision of multiple other ecosystem services. Looking at the surrounding landscape, we can understand what the natural environment has provided to the farm system, and what the farm system provides back to the natural environment. Sometimes we look a meter out, sometimes a kilometer out.
But beyond just the space we look at, we're really looking at time. Nature takes time. When you look at the field, it's an observation of what has been going on there for a very long time.
How does agroecology research work with farmers?
Working with farmers helps give research the long-term lens and management gradients we need to understand these agricultural systems, and gives us a landscape lens that many research fields can't provide. It also helps relate our research to production constraints that farmers have.
There is also tremendous innovation in what farmers are coming up with. They have a specific problem and they usually have tried specific solutions. They test things out, they monitor their fields and see results, but maybe don't understand fully the underlying mechanism and potential impact on the environment. We try to get to the why; we try to connect the dots to enable scaling up and better understanding of the ecological processes regulating resource use efficiency.
We're also looking a lot at resilience to stresses. And we find more and more interest in this because resources are not plentiful anymore and we now have to produce more with less. So how do we build resilience to the multiple stresses that come along? Are there ways that the management of a farm can impact productivity when a stress like drought occurs?
We have a lot to learn from small growers and a lot to learn from growers who have constrained resources about what they have been implementing and experimenting with. How can we transfer those practices to different environments? How can we scale them up?
How can we make it work in large-scale agriculture? There's a huge opportunity there. I want to see agroecological approaches to management implemented all over the Midwest, all over the Central Valley. I think agroecology is compatible with large-scale agriculture and critically needed.
How do you approach research questions?
I start with the problems a farmer didn't have. One project started with a tomato farmer who didn't have the same insect problem that surrounding farms had. So we ask, what is he doing that created this insect resistance, and how can that be used by other farmers? We met with several different farmers to discuss the issue, and wrote a grant to investigate specific hypothesis across a management gradient.
We're now working with five different growers and using Russell Ranch, our long-term agricultural research facility, as a benchmark.
I think conversation with farmers and their advisors is critical to develop relevant research questions and alternatives which have conservation of natural resources, biodiversity and provision of ecosystem services as a basis for improvement. It is also important to keep a positive feedback loop and bring results back to the community to foster farmer-to-farmer knowledge transfer.
What excites you about this new investment in agroecology?
The context of agriculture is changing and we now have a tremendous opportunity to promote agroecology as a viable and necessary strategy to build the sustainability and resilience of our agriculture. Farmers are seeking solutions, they are aware and interested. With climate change and depleted resources becoming more of a reality, growers are interested in putting soil improvement and ecological principles back into their management framework. And I think we ultimately care about the same things, we just need to find common ground and start speaking the same language. To do it we have to be open minded, both on the researcher and farmer side.
Investment in agroecology will help us reach this objective and gives us an opportunity to think outside of the box. This gives an opportunity to be creative, cope with some of the pitfalls of science funding and take a participatory approach to interdisciplinary research to design holistic solutions that better use nature for a sustainable agriculture./h3>/h3>/h3>/h3>/h3>/h2>/h2>