12 Aug 2008

Updated Numbers You Need to Know

Earlier today, I posted on the amount of water used by agriculture in California but added the caveat "I'd like to have a source on the water consumption of those four crops."

I asked Lloyd Carter, whose post I had cut and pasted, if he had sources for the consumption figures. He said that the figures originated in Reisner's Cadillac Desert and sent me two stories published in the last year (LA Times and Christian Science Monitor) that said that "cotton, rice, alfalfa and irrigated pasture" were responsible for 30-50% of irrigated water.

Well, I'm an academic (right?), so I went to primary sources to see what kind of data I could get. Here's what I got from the 2003 USDA Census of Agriculture [PDF].*

These crops -- the top ten -- use 95% of the irrigation water in California:






















































CropFarmsAcresAF/ACTotalAFShare(%)
Orchards 34,5602,750,0002.46,600,00026%
Alfalfa 2,638 1,008,000 3.7 3,729,600 15%
Veggies 3,253 927,000 2.9 2,688,300 11%
Rice 1,175 596,000 4.1 2,443,600 10%
Cotton 1,292 757,000 2.9 2,195,300 9%
All Corn 2,800 688,000 2.8 1,951,500 8%
Pasture 5,826 512,000 2.6 1,331,200 5%
Tomatoes 1,942 355,000 2.8 994,000 4%
Wheat 1,038 407,000 2.2 895,400 4%
Hay 1,885 345,000 2.5 862,500 3%
These numbers are applied water per acre -- not consumptive water/acre.

So -- the four "low value crops" are responsible for 39% of water used in irrigation in California, so that statistic is holding up -- as least as far as the most-recent data are concerned.

More tidbits:
  • According to this table [PDF], California has 47,000 farms using a total of 25 million AF of water.**
  • California has over 60 percent of national acreage for orchards and 40 percent for vegetables.
Bottom Line: California agriculture is putting a lot of water on some low-value crops. If water was selling at "market" prices, I'd bet those crops would use 25 percent or so.

* The 2008 Census will probably come out next year.

** These statistics do NOT match information provided by the California's Departments of Food and Agriculture (88,000 farms) or Water Resources (34 MAF of water) unless you think there are 40,000 non-irrigated farms. Given the CDFA's interest in inflating the number of farms, I am willing to trust USDA figures on farms, but the 9 MAF difference may be due to different supplies in different years.

6 comments:

  1. Oooh, how I love to quibble.

    Generally the Census is referred to by the year of data collection (2002 and 2007), rather than year of publication. Unless you are referring to the 2003 Farm and Ranch Irrigation Survey, which supplemented and was somehow integrated into the Census.

    How long are you going to remain in DC, by the way?

    db

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  2. yep -- you got me there, except that the docs say "2003 data" - so blame USDA.

    I'm back in Berkeley. Now you have to visit ME :)

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  3. I'm always happy to blame USDA.

    Pity I missed you, though. Pretty lame, and my only excuse is that I am only in DC half the time, but mainly it is lameness.

    db

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  4. Many of these "lower value" crops might be grown in a cooler season when other crops cannot be grown or they may be part of a rotation. Alfalfa is definitely used as a rotational crop for sustainable agricultural practices. It is a nitrogen fixer and is often rotated as part of the cycle for that reason... It brings in a lot of beneficial insects as well and can create refuge for other non-beneficial insects that may impact higher value crops.

    Also wheat and grains are often part of a rotation. Like alfalfa you can grow them in a cooler season when you can't grow higher value I grow them every winter or whenever I am not growing row crops in an area. I use them as a green manure adding organic matter to the soil and preventing erosion from wind and water, and leaving land open and dry making it susceptible to high UV that destroys organic matter. They also shade out weeds and prevent further weed production.

    The reality is you can't grow high value crops on every inch of agricultural land, it is NOT sustainable. And you can't fallow leaving land open and dry and susceptible to environmental conditions, like erosion issues and weed issues. Some farmers say for every year you don't work the land it takes five years to get it back into production.

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  5. In Washington state if you do not use your water rights for 5 years you lose them.

    Often Alfalfa or hay are grown simply to preserve ones water rights.

    I don't know how water rights work in California, but if people are growing alfalfa in in the desert I suspect something screwy like what is happening in Washington is going on.

    Joshua Corning

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  6. Many places where pasture and other forage crops are grown are not suitable for other uses, as other posters have pointed out. In addition, in many instances it would be physically impossible for pasture water to be conveyed to others (although it would be possible for environmental interests to pay farmers not to use their water on pastures, but to leave some or all of it in streams). I think the environmentalists would be shocked to see that if they reduced riparian hay and pasture areas, many fine fishing streams would suffer greatly.
    Farmers are selling water already, in the form of crops and animals. If we can confirm a property right and value in the water per se, it will be up to the farmers, and the free market, to decide whether it is more valuable to turn their water into crops or cash. Big government types of all colors hate this idea because they won't have control.

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