Posts Tagged: Randall Southard
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.
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