Merced researcher: Cows' diet can hurt soil, groundwater

jsmith@mercedsunstar.comApril 3, 2013 

— When it comes to a cow's diet, many dairy farmers err on the side of caution, often feeding their cows more salts and other minerals than are necessary, according to a report in the Journal of Dairy Science.

While ingesting unnecessary minerals may have little direct effect on cows, inadequate amounts of these essential nutrients can cause a host of health problems and reduce productivity.

However, the practice of overfeeding salts and other minerals to cows can negatively affect soil and groundwater quality, according to report author Alejandro Castillo, a University of California Cooperative Extension researcher in Merced.

"This is going to be important for the sustainability of our dairy farms," he said. "We need to try to see the future and imagine the sustainability of our dairy farms and maintain the business for a long time."

Cow manure with high mineral and salt content can seep into the ground, degrade the quality of soil and over time make the land unsuitable for farming, according to the report.

Tweaking feed recipes can go a long way toward protecting farmland in and around dairy farms, Castillo said.

"We can improve concentration of minerals in the diet," Castillo said. "We can identify the minerals in our feed and improve mineral balances in our cows."

High salt levels don't just threaten dairy farms.

The entire valley is at risk from oversalinization, said Parry Klassen, chairman of the executive committee for Central Valley Salinity Alternatives for Long-Term Sustainability.

"It's an absolutely huge problem in our region. In some areas, the salt build up is as high as nitrates," he said. "In the end of the day, if we don't change our ways, the valley's going to be salted out."

Much of the valley's West Side is irrigated with water from the Sacramento-San Joaquin Delta that also contains salt, Klassen said.

"Every time you irrigate with that water, you're putting a certain amount of salt on that field that has no place to go except the soil or the groundwater," he said

CV SALTS, a stakeholder-led group put together by the state, has been working with state and regional water boards to come up with a management plan to address oversalinization.

The group is expected to bring a draft salt management plan to the Central Valley Regional Water Quality Control Board by May 2014, according to water board officials. A final plan is due by 2016.

The plan likely will be the basis for regulations and programs to limit salinity in the valley, said Jeanne Chilcott, senior environmental scientist with the water board.

"The problem with salts has been recognized for decades," she said. "What's happening is that things are building up quickly."

Reporter Joshua Emerson Smith can be reached at (209) 385-2486 or jsmith@mercedsunstar.com.

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