Sustainable agriculture practices in the western San Joaquin Valley are advancing through a research partnership featuring a Fresno County grower and scientists from the USDA and California State University, Fresno.
The research team has succeeded in reducing selenium content in West Side soils by growing canola, processing the seed oil to be mixed with diesel fuel and then using the canola meal by-product – with trace elements of selenium – as a supplement for cattle feed.
The continuing project is directed by Gary Banuelos of the USDA’s Agricultural Research Service based in Parlier, Calif. Cooperators include Fresno State chemistry professor Alam Hasson and grower John Diener, owner of Red Rock Ranch in western Fresno County.
The research focusing on canola was undertaken for several reasons, Banuelos said. First, canola has been shown to tolerate and absorb more selenium from irrigation water than most agronomic crops. Second, canola seed can not only be processed into cooking oil, but also “transesterified” for use as a blend with diesel fuel. Third, the “press cake” left over following processing shows potential not only as a livestock feed but also as a source of supplemental selenium.
So far two of the three key objectives of the research project have been met, Banuelos said in a recent report to the Fresno State-based California State University Agricultural Research Initiative (ARI), which funded the research jointly with Diener.
“In order for canola to be widely accepted as a crop and be used as a practical tool to manage selenium content of drainage water produced on the West Side, it is imperative that viable economical uses for the plant product also be available,” Banuelos said.
The canola plant, because of its inability to discriminate between absorbing sulfur or selenium ions, can successfully extract selenium from irrigation water, research has shown.
Part of Banuelos’ project included constructing a small-scale oil production facility on the Diener ranch near Five Points so that the entire growing and processing experiment could be conducted on-site. Work included assembling a model 2000 Insta-Pro Extruder and a model 1500 Insta-Pro Continuous Horizontal Press. Other equipment used in processing included a seed hopper, cooling unit and oil storage tanks.
Canola growth trials conducted on the ranch resulted in average seed yields of at least one ton per acre, using poor quality drainage water for irrigation, Banuelos reported. With seeds yielding from 35 percent to 40 percent oil, approximately 100-160 gallons of 100-percent bio-oil were produced from 1 ton of seed.
Once transesterified, the canola oil was mixed at a rate of 20 percent with standard diesel fuel to create B20 biofuel for operating diesel-powered engines. The small-scale oil processing and diesel engine operations were successful, Banuelos said.
“On a larger scale, successful operation would require abundant seed for oil extraction, larger oil mill facilities, and alternative and cheaper sources of energy-to-electricity for operating the oil press before sustainable production of biofuel and selenium-enriched meal can be realized on California’s West Side,” he said.
The third phase of the project includes evaluating the selenium-enriched seed meal as a livestock feed amendment. That trial is under way at the Fresno State dairy, involving different feeding regimens for two groups of 37 Holstein and Jersey cows each. The regimens include a control treatment along with two different feeding mixes, followed by periodic milk and blood draws from the cows to determine blood selenium and other nutrient levels.
The canola plant has the potential to fit an important niche in San Joaquin Valley agriculture, but it would require business partnerships between farm groups, including the livestock and dairy industry, Banuelos noted.
“Canola meal is one of the most widely-traded protein ingredients in the world – its use in animal feed rivals soybean meal because of its high nutritional quality in terms of fiber, protein, and fat,” he said.
And through its selenium uptake from the soil, West Side canola can also be a selenium source in livestock feed.
“Selenium at low concentrations is essential in animal production,” Banuelos said. “And the benefit of having selenium in canola meal at this concentration is that we don’t have potentially toxic levels when it is used as part of a daily feed ration. And importantly, the organic source of selenium may be more bio-availability for absorption.”