Heavy Rain Peppers Salt Clogging Trees’ Roots : Agriculture: Storms can assist in flushing away the substance that blocks the absorption of water and other nutrients from the soil.

Amid the booming thunder and pounding rains of this week’s storms, Carolyn Leavens quietly rejoiced, relieved that the deluge had come in time to dislodge the salt that was slowly choking trees on her family’s citrus and avocado ranch.

Like all Ventura County growers, Leavens irrigates her crops with ground water. But that water carries high concentrations of salt, which collects around tree roots in crusty rings and blocks the trees’ absorption of water and other nutrients from the soil.

This week’s storms, coming hard on the heels of January’s torrential downpours, flushed away much of the salt that had been strangling Ventura County’s orchards, growers said.

“After a rain, it’s almost like the trees are clapping their hands and saying, ‘Oh this is so wonderful,’ ” said Leavens, whose family owns 1,000 acres in the Santa Clara River Valley. “A gorgeous rain such as the one we’ve been enjoying cleans everything out beautifully.”

In a typical year, routine irrigation deposits four tons of salt on every acre of land, according to Scott Bucy, an agronomist with the Fruit Growers Laboratory in Santa Paula. That works out to about 80 pounds per tree--enough to clog up root systems and retard growth.

“Salt is not any better for the trees than it is for us,” said Susan Petty, who owns 57 acres of lemon trees in Saticoy.

Unable to pull food and water from the soil, the trees start to shrivel up. Leaves turn yellow or brown, and fruit production plummets.

And only a good, hard rain can wash the salt away from the roots, down deeper into the soil.

Storms also sweep the dust off tree leaves, depriving crop-destroying bugs of their favorite burrowing grounds.

So while growers of low-lying produce like lettuce, strawberries and broccoli generally fear rain will flood fields and bruise crops, avocado and citrus farmers welcome every drop.

“What the trees would like is rain year-round,” said Avi Crane, vice president of the California Avocado Commission. “They prefer rain to irrigation.”

They probably won’t be getting more this week, however, as meteorologists pronounced the storm over by late Tuesday. Forecasters predicted partly cloudy skies today with temperatures in the 60s.

“There will be a slight chance of rain on Saturday, but it doesn’t look like it’s going to be anything significant,” said Dean Jones, a meteorologist for WeatherData Inc.

Paradoxically, light showers can exacerbate growers’ problems with salt.

Gentle drizzles tend to push salt down through the soil, where it begins gnawing away at the roots. If the rain doesn’t pound hard enough to pummel the salt past the roots, farmers may have to step in with forceful sprinklers that finish nature’s job off right, Crane said.

Of course, such an approach can also be harmful, because the water used to push salts away from the roots usually comes from a salty aquifer--and thus the farmer ends up depositing more salt on the soil’s surface.

“Salts are one of the biggest problems in agriculture,” Bucy said, noting that fruit and vegetable harvests can shrink by up to 60% in a dry year due to salt accumulation.

John Newman, who owns a 920-acre citrus ranch near Point Mugu, remembers back to the 1930s, when a half-inch of salt covered the Oxnard Plain like snow during dry seasons. In those days, the only crops that grew on the alkaline land were sugar beets and barley--plants with a high tolerance for salty soil.

Now that growers have laid underground pipes that drain into the ocean, they can flush the salt out of their fields with fresh water, Newman said. The water trickles through the porous pipe and runs out to the Pacific.

“It’s just that much better” when storms do the work for them, Newman said. “We can always use lots of rain.”

Times staff writer Maia Davis contributed to this story.

County Rainfall

Here are rainfall figures from 8 a.m. Sunday to 5 p.m. Tuesday from the Ventura County Flood Control District. Oct. 1 is the beginning of the official rain year.

Rainfall Rainfall Normal rainfall Location since Sunday since Oct. 1 to date Camarillo 1.57 15.68 8.03 Casitas Dam 4.31 27.37 13.96 El Rio 3.28 17.29 8.92 Fillmore 3.38 22.55 11.31 Moorpark 2.59 17.71 8.71 Ojai 4.47 29.06 12.51 Upper Ojai 5.81 30.05 13.47 Oxnard 2.20 14.77 8.59 Piru 2.92 22.46 10.16 Santa Paula 3.86 21.05 10.49 Simi Valley 3.19 18.85 8.37 Thousand Oaks 2.90 19.49 9.03 Ventura Govt. Center 3.56 17.88 9.50