Canadian Light Source involved in California drought study

“The use of cover crops turns the soil into a sponge that holds water,” Ying said in a news release. “But how does this work? We really don’t know what’s happening to the carbon and soil.”

The research project began in 2015, at the end of a record-breaking four-year drought in California. Teams of scientists from three UC campuses looked at various ways to make the soil more resilient. Ying said they focused on areas that were heavily dependent on irrigation for crop production.

“We’re looking at how we can inform farming practices to get the same yields but with lower water use,” Ying said.

In a short-term study, researchers used a field at the Russell Research Sustainable Agricultural Facility, for a tomatoes-fallow-tomatoes rotation. The field was then divided; one half was planted with a common cover-crop mix of vetch, bell beans and Austrian peas while the other was left fallow.

Ying said soil samples were analyzed at CLS to determine what kinds of carbon were present and where.

“Soil is basically sand, silt and clay that forms aggregates or balls of different sizes which are held together by organic compounds. The bigger the ball, the more water can be held inside that’s available to plants,” Ying said.

Their study analyzed the carbon present in the samples, and showed little difference in the size of the aggregates formed in soil with and without cover crop. There was also little difference in the amount of carbon in the aggregates, but new carbon from the cover crops were seen to accumulate in the larger soil balls.

Schaefer said the results point to the need for further investigation but they would not have learned what they did without travelling to the CLS.

“The people there are very supportive of agriculture research,” Schaefer said. “They’re extremely knowledgeable and the facility is amazing. The high-resolution spherical grating monochromator beamline lets us look at what kind of carbon is present without having to destroy the samples.”

Schaefer said more research is needed to determine the actual cost in terms of water use to grow cover crops in different regions.

Ying said this is the first of many papers for the California project. In addition to the water cost of cover crops, she expects future investigations will include carbon buried deep in soil, and soil microbiome.

“The microbes and fungi in any soil are extremely important to understanding how carbon is sequestered,” Ying said.

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alice.mcfarlane@jpbg.ca

On Twitter: @AliceMcF

by Alice McFarlane

Canadian Light Source involved in California drought study

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