A comprehensive study involving California State University, Fresno-based researchers, indicates possibilities for new farming methods on the West Side of the San Joaquin Valley, which is challenged by selenium-laden irrigation effluent.

The research work began in 2006 with a research partnership among California State University’s Center for Irrigation Technology at Fresno State, a U.S. Department of Agriculture soil scientist and West Side farmer John Diener.

West Side growers have tried to reduce their production of selenium-laden irrigation effluent to sustain agricultural land, said Gary Banuelos, lead researcher on the project. He represents the USDA’s Agricultural Research Service based in Parlier.

One method of using excess selenium in West Side drainage water is to apply the water to salt- and selenium-tolerant crops. Several of these crops are in the brassica family, which includes canola and mustard.

“For canola to be widely accepted as a crop and be used to manage the volume and selenium content of effluent produced in the West Side, it is imperative that viable economical uses for the harvested plant product be created,” Banuelos said in a report on the project.

The primary goal of the project was to successfully grow canola using selenium-laden drainage water. Over two years at Diener’s farm southwest of Fresno, the research team established several 40-hectare plots planted to canola and mustard.

The test plots were irrigated with water high in selenium, yet the crops still produced a maximum seed yield of 2.2 metric tons per hectare, Banuelos reported. More than 300 tons of brassica seed were harvested and processed over the course of the experiment.

The second project phase was to press the harvested seed for oil that could be blended with diesel fuel. This was accomplished on Diener’s ranch with research funding provided by the California State University Agricultural Research Institute, state Department of Water Resources and the USDA’s Agricultural Research Service.

The funding enabled purchase of a dry extruder and oil press capable of extracting up to 90 percent of the available oil from the canola and mustard seed.

With cooperation from Russ Teal of Biodiesel Industry in Santa Barbara, the pressed oil was processed and blended with commercial diesel fuel to produce Biodiesel (BD) 20. The biofuel was successfully used to power 5.9-liter Cummins diesel irrigation booster pumps on Diener’s DK Farm.

The final project goal was to produce nutritious, palatable cattle feed supplement that would meet selenium needs of dairy cattle. Under the supervision of Dr. Jon Robison, a dairy science professor at California State University, Fresno, feed trials were conducted at the Fresno State Dairy.

“These studies showed that selenium-enriched canola and mustard did not significantly increase total blood and serum Se content in either cow breed,” Banuelos said. And while selenium concentrations in milk increased, they remained at safe levels.

Additional long-term studies should be conducted, Banuelos said, but the initial outlook is encouraging.

“Our testing demonstrated that the coupling of selenium phytomanagement with biofuel production may provide growers with a unique opportunity to increase environmental sustainability in areas with high selenium conditions, and at the same time reduce use of petro-diesel in sensitive parts of California,” Banuelos said.

In addition, with more than 1.8 million dairy cows in California alone, there is a large market for selenium-enriched brassica feed meal that could be met from the West Side, he said.

For more information on this research, contact Banuelos at gary.banuelos@ars.usda.gov.

(Text by Steve Olson of the California Agricultural Technology Institute.)