Jul 23, 2014

California growers, researchers doing what they can to conserve water

The 2014 drought will cost California’s economy $2.2 billion and 17,100 seasonal and part-time jobs, according to a study released in July by the University of California’s (UC) Center for Watershed Sciences and Agricultural Issues Center.

The study states that the 2014 drought is “responsible for the greatest absolute reduction in water availability for California agriculture ever seen.” Surface water availability is expected to be reduced by about a third. Agriculture will lose about 6.6 million acre-feet of surface water. That loss will be partially replaced by pumping an additional 5 million acre-feet of groundwater, but the extra pumping will cost $454 million – and the net shortage of 1.6 million acre-feet will cause losses of $810 million in crop revenue and $203 million in dairy and other livestock value. Thus, the direct costs to agriculture will total $1.5 billion, according to the study.

Seventy percent of the state’s crop revenue losses and most of its dairy losses are likely to occur in the San Joaquin Valley, where most of the state’s fallowed acres are expected. Most of the fallowing is estimated to be lower-value irrigated pasture and annual crops such as corn and dry beans. Higher-value crops, including vegetables and fruits, are expected to be fallowed at lower rates, according to the study.

However, California’s tree fruit and tree nut growers are expected to irrigate 41,000 fewer acres in 2014, for a loss of $277 million in revenue. The state’s vegetable and non-tree fruit growers are expected to irrigate 10,000 fewer acres, for a loss of $47 million, according to the study.

The study stated that 2015 is likely to be another dry year. Continued drought in 2015 and 2016 would lead to additional overdraft of aquifers and lower groundwater levels, thereby escalating pumping costs, land subsidence and drying up of wells. It could cost Central Valley crop farming an estimated $1 billion a year, according to the study.

The long-term loss of groundwater is another threat. Groundwater might replace as much as 75 percent of the lost surface water this year. That would raise groundwater’s share of the agricultural water supply from 31 percent to 53 percent. Failure to replenish groundwater in wet years will continue to reduce its availability, however – particularly for the more profitable permanent crops – during California’s frequent droughts, according to the study.

Conserving water

To help Californians adapt to drought, University of California (UC) Division of Agriculture and Natural Resources (ANR) and Cooperative Extension (UCCE) researchers are finding ways for them to use less water.

“This drought is unprecedented – we’ve never had such a lack of rainfall since we started keeping track,” said Doug Parker, who directs ANR’s California Institute for Water Resources. “It’s something we need to learn to live with.”

During most years, agriculture uses 80 percent of the state’s developed water, according to a UC research article.

“Farmers are looking for ways they can stretch their water budget,” Parker said.

He estimated that about 5 percent of the state’s irrigated cropland would be fallowed in 2014.

But not every farmer has the option to fallow. Permanent crops like almonds and grapes need some water just to stay alive, so growers often turn to groundwater when supplies of surface water are cut, according to the UC article.

“This is not sustainable in the long run, but is not a bad thing in the short run,” Parker said. “It’s a loan and we need to remember to pay it back.”

The avocado is an example of a plant that needs plenty of water. Avocados are shallow-rooted trees and need frequent irrigations throughout the day. On top of that, California avocados grow along the coast from San Diego to Santa Cruz, where water is pricey and contains salts that can affect the trees’ productivity. Avocado growers can’t use less water, but they can boost their irrigation efficiency, according to UC.

“Sprinkler systems … can get out of whack – monitoring them optimizes water delivery,” said Ben Faber, UCCE farm adviser for Ventura and Santa Barbara counties.

Faber said too much or too little water can cause serious root diseases.

Unlike avocados, wine grapes are naturally water thrifty. But water is scarce in Paso Robles, a premier wine grape-growing region that lacks water deliveries from state and federal projects, according to UC.

“We depend almost entirely on groundwater,” said Mark Battany, UCCE viticulture farm adviser for San Luis Obispo and Santa Barbara counties.

In contrast to surface water, groundwater is not regulated in much of the state, and reserves in many areas are going steadily downward, according to UC.

Battany is looking for ways to make wine grapes thrive with less water. For example, vines are grown close to the ground because that’s what works in Europe, but that might not be best for Paso Robles, where the air near the ground is often cold at night when the vines start to leaf out in the spring. Currently, some growers protect their vineyards from frost by sprinkling them with water (the transition from liquid water to ice produces heat, which insulates the buds from the cold), according to UC.

Battany is exploring an alternative to using irrigation for frost protection that could help protect vines from summer heat and climate change. His approach hinges on the fact that air near the ground is coldest at night and hottest during the day.

“Training the vines to grow taller could avoid both extremes,” he said.

Battany is assessing the temperature of air at a range of heights above the ground. He’s also studying the ability of wind machines to offer water-free frost protection, according to UC.

UCCE Mendocino County viticulture and plant science adviser Glenn McGourty is getting ready for a drier and warmer future.

“We’re rethinking and redesigning vineyards,” he said. “Current rootstocks are from northern France, so they don’t take the heat well.”

He’s testing varieties that send their roots deeper and that thrive in hot places like Greece and Portugal, according to UC.

– Matt Milkovich