Farmers dealing with unwelcome 'snow'

Mar 17, 2014

Due to the lingering drought, farms in the San Joaquin Valley are being found with an unwelcome white dusting of "snow" on the soil surface. It isn't the snow so desperately needed in California's high country; rather it is salt and other toxins that have precipitated out of the soil because of sparse winter rains, reported Dennis Pollock in Western Farm Press.

At the recent California Plant and Soil Conference in Fresno, multiple speakers showed pictures of what they labeled "California snow," the article said.

Plant toxins like selenium, boron and salt leach out with water, but water is in short supply this year. "That's why a lot of land is fallow," said Gary Banuelos, USDA-ARS researcher in Parlier.

At the conference, Rick Snyder, UC Cooperative Extension specialist in the Department of Land, Air and Water Resources at UC Davis, said applying less water will reduce deep percolation and could result in higher salinity in the rooting zone. Eventually deficit irrigation will become problematic, especially if practiced over a longterm drought.

Snyder said it might be better to apply available water to a smaller area to maintain production. In the case of permanent crops, he suggested the same frequency of irrigation, but using less water with each application.

David Doll, UCCE farm advisor in Merced County, said almonds are sensitive to high levels of sodium, chloride and boron; and that some rootstocks are more tolerant of saline conditions than others.

Dan Putnam, UCCE specialist in the Department of Plant Sciences at UC Davis, said alfalfa may be capable of tolerating higher salt levels than previously thought.

Some degraded water that could not be used on food crops can be used on alfalfa, he said, adding that alfalfa is in higher demand than many other salt-tolerant plants. While salinity may trigger a decline in percentage of germinated seeds, Putnam said, “that doesn't scare us; we can live with a 40 percent level.”

Blake Sanden, UCCE advisor in Kern County, said there are research gaps with regard to soil toxin tolerance in pistachios.

However, he said, a buildup of boron in the soil is "a potential boron time bomb."

Sanden's research showed a doubling of total boron in the soil after nine years. Without 6 to 10 inches of rainfall or fresh water winter irrigation for leaching every one to two years, he said, high levels of boron could render pistachio production unsustainable.

By Jeannette E. Warnert
Author - Communications Specialist