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Which crops produce most ‘pop per drop’ of water?

Gino Celli inspects wheat nearing harvest on his farm near Stockton last month. Amid the drought, UC Davis researchers are looking at how much crops produce in revenue and jobs for the amount of water they use.
Gino Celli inspects wheat nearing harvest on his farm near Stockton last month. Amid the drought, UC Davis researchers are looking at how much crops produce in revenue and jobs for the amount of water they use. The Associated Press

With California stuck in a historic drought, there’s no shortage of blaming and shaming on who’s using how much water.

Homeowners wag their fingers at farmers, farmers bash developers, environmentalists say fish need more water and so on. We’re all making value judgments on the best uses for precious water.

Within California’s huge and important agriculture industry, distinctions are being made between crops eaten domestically, ones that are exported and those consumed by animals, not people.

In this food fight, researchers at the UC Davis Center for Watershed Sciences are doing some very interesting work, available at California WaterBlog. In studies that flew under the radar, they looked at how much water is needed to grow various crops – but in terms of the return on that investment in revenue and jobs.

“Pop per drop,” they call it, which has a nice ring to it.

A category of crops that include vegetables such as carrots and lettuce, along with garden plants and strawberries, produce the highest revenue for net water used ($14,318 per acre-foot). The broad category of fruits and nuts also ranks high ($2,392). Combined, these two categories account for nearly 90 percent of crop revenue, but less than half of irrigated acreage.

Grapes – table, wine and raisins – generate $3,129 per acre-foot. Corn and cotton are more in the middle of the pack. Rice ranks lower, but also provides important habitat for waterfowl.

Alfalfa ($357) and other pastureland ($91) provide the least revenue per acre-foot of water. Overall, livestock feed directly produces only 7 percent of revenue, but uses nearly 37 percent of water consumed by agriculture.

But before you tar them as villains, the researchers point out that ranches and dairies that rely on the feed generate nearly a quarter of the state’s agriculture production value.

Measured by jobs created for water consumed, the category of vegetables, garden plants and non-tree fruits also ranks highest (75 jobs for every 1,000 acre-feet). Melons and cucumbers do well (70 jobs), as do fresh tomatoes (62 jobs).

The job numbers fall off rather dramatically for other crops, including grapes, oranges and lemons. Much-vilified almonds and pistachios produce a paltry 4.6 jobs per 1,000 acre-feet. Alfalfa and pastureland again rank lowest because they are highly mechanized and require little labor in the fields.

The main takeaway is that it’s much more complicated than purely how much water it takes to produce a single almond, or head of lettuce or glass of wine – comparisons very popular these days, especially on the Internet.

As a whole, the state’s agricultural economy is getting whacked by the drought, now in its fourth year.

In preliminary estimates released this week by the UC Davis team, farmers are expected to have a net water shortage of 2.5 million acre-feet, 1 million more than last year. That would force them to fallow a projected 560,000 acres, or about 6 percent of average irrigated cropland.

The results: a $1.8 billion cost to agriculture (lost crop and livestock revenue and additional groundwater expenses) and 18,600 fewer jobs than if there were no drought.

These are the numbers that grab more headlines. They’re a good reminder that while city dwellers may not like brown lawns, in farm country, the lack of water is about people’s livelihoods.

By the numbers

Selected crop categories in California, how much revenue they produce per acre-foot of water and how many jobs per 1,000 acre-feet:

  • Carrots, lettuce, flowers, strawberries, $14,318, 74.8 jobs
  • Grapes, $3,129, 22 jobs
  • Almonds, pistachios, $1,452, 4.6 jobs
  • Cotton, $692, 4 jobs
  • Rice, $524, 1 job
  • Alfalfa, $357, 0.8 jobs
  • Pasture, $91, 0.3 jobs

Source: UC Davis Center for Watershed Sciences

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