Rice fields near Sacramento in 2009. Photo by Paul Harnes/California Department of Water Resources
By Josué Medellín-Azuara and Jay Lund
When it comes to water, California’s irrigated agriculture is always under the public magnifying glass because it is the largest managed water use in the state and the economic base for many rural areas. During a prolonged drought like the current one, however, crop water comes under a microscope.
We have compiled a table to help answer questions on which crops use the most water and which crops provide the most economic “pop per drop.”
The estimates are very broad because California is so diverse in crop varieties, agricultural practices and local water availability. But the numbers are still useful for comparison purposes.
Note that the amount of water applied to a crop – “gross use” – is not the same as its “net use,” as some of that water seeps underground and replenishes aquifers or is reused downstream.
Some observations about the data:
- The “truck (vegetables) and horticulture (garden plants)” crop group has the highest revenue per net water use, followed by the “fruits and nuts” group. Together, these two large crop categories account for nearly 86 percent of all crop revenue, but occupy only 47 percent of the irrigated cropland and use just 38 percent of the water applied to that land.
- Fruits and nuts are grown on about one-third of the irrigated cropland and use one-third of the water, but produce nearly 45 percent of the total crop revenue.
- Alfalfa, corn irrigated pasture and other livestock fodder account for nearly 37 percent of all net water crop use, but produce less than 7 percent of total crop revenue. However, the ranches and dairies that depend on these foodstuffs generate more than 22 percent of California’s agricultural production value, which totaled $45 billion in 2012.
- Rice fields use a lot of water but also provide important bird habitat.
Josué Medellín-Azuara is a senior researcher and Jay Lund is a professor of civil and environmental engineering with the UC Davis Center for Watershed Sciences.
Thanks for sharing this great chart of how much water it takes to grow crops in California! Very helpful information.
Can someone explain some of the categories better:
What are the “other field crops”?
What does “truck” mean in the truck and horticulture category?
Which category do vegetables, melons and things you would find on people’s plates fall in?
What category are grapes in and does that include table grapes, wine grapes and raisin grapes?
Uti,
“other field crops” would be things like wheat, barley, etc., any non vegetable crops not in the named catagories
The rest of your questions are answered in the “observations about the data” below the data field, all grapes are fruits, which would be in the fruits and nuts catagory.
Thanks Bill. I overlooked those on my first reading.
How much of that alfalfa crop is shipped overseas, Asia, Middle East,
China, etc. to feed their beef herds, so they don’t have to use up their own precious water? Aren’t we selling ourselves down the drain for the all mighty dollar?
“A hundred billion gallons of water per year is being exported in the form of alfalfa from California,” argues Professor Robert Glennon from Arizona College of Law. That water comes from both California watersheds and Colorado River Basin in the case of Imperial Valley farms.
It’s cheaper to ship it overseas in all those empty cargo containers than it is to truck it to other locations in the state one farmer was quoted saying in the LA Times. http://www.latimes.com/business/la-fi-feeding-china-hay-20140609-story.html#page=1
The usual justification for exporting water in the form of hay is the balance of trade deficit with China, since they are the fastest growing buyer of hay next to the United Arab Emirates, but I question the morality of that when farmers in the Central Valley are forced to fallow fields and lay off workers that grow food for people. It also leaves us in the position of cutting back environmental flows and possibly endangering fish and wildlife habitats. So yeah, I agree we are selling ourselves down the drain so that a few people can get rich off of whatever crops are in high demand for export.
Unfortunately we have a system where success is measured only in dollars of profit, so telling farmers what they can grow and when is not part of the picture.
Those wanting to not export food might want to advocate not importing things that are paid for with exports. There is also much water embodied in the cars and computers we import, so it isn’t all one-way. See:
http://californiawaterblog.com/2014/02/27/virtual-water-vs-real-water-in-california/
The funniest rogue’s gallery for this drought I’ve seen is:
http://www.npr.org/blogs/thesalt/2015/04/12/398757250/beyond-almonds-a-rogues-gallery-of-guzzlers-in-californias-drought
The commentary on this blog has been wonderful antidote to the alarmism in the press.
An increasing number of popular articles seem to be referring to actual hydrologists and refer to scientific work on water usage, this is a good thing.
How do the authors feel about the following statement:
“The drought is primarily a matter of who wants to subsidize animal agriculture.”
As this blog has noted, water usage varies locally, but something gets lost when we say things like “irrigated agriculture…is the largest managed water use in the state”. The statement is of course true, but hides differences in water efficiencies across crops.
I think that the table in the article is misleading, the “fruits and nuts” are one category when (to the best of my knowledge) they have very different water efficiency profiles (http://waterfootprint.org/en/). That website provides some very clear advice on decreasing one’s water footprint: adopting a vegetarian diet. I do not see this advice mentioned on California’s public face of anti-drought efforts: http://saveourwater.com/. In fact much of that site seems to avoid explaining water usage in an honest scientific way, and seems to almost intentionally obfuscate effective methods for individuals to reduce their water footprint.
Would love to hear your critical thoughts on the above.
I should’ve said that that the drought is also a matter of trade policy (as jaylung points out in an earlier comment), but individuals have little control over policy in the short term (and are maybe happier trading in their almonds for iWatches). Just trying to explain my focus on animal agriculture.
Addressing the water crisis isn’t necessarily as simple as going more-vegetarian or quasi-vegan (no one is 100% vegan given the widespread interplay of animals with food production and society in general). Something to keep in mind is the fact that there are multiple inter-connections between plant agriculture and animal agriculture. One, for example, is the beneficial use as animal feed of the waste product(s) of plant food production.
By-products from plants have to go somewhere and if not to animal feed (or other beneficial use) they enter the waste stream with all the associated effects and disposal costs. As just one of many examples, this link http://www.feedipedia.org/node/680 (a joint project of the Food and Agriculture Organization–FAO–of the United Nations) notes, “Citrus …is one of the most important fruits crop worldwide…About 30% of the production of citrus fruits (and 40% of orange production) is processed (USDA-FAS, 2010), principally to make juice, and results in large quantities of by-products…Citrus pulp is used as a cereal substitute in ruminant feeds, due to its high energy content and good digestibility in ruminant species. Fresh pulp is often used locally to feed animals. Fresh citrus pulp has a natural acidity but it is still a perishable product due to its high content of water and soluble sugars (Rihani, 1991). It may quickly sour, ferment and release sludge hazardous to the environment…Citrus juice production is often a highly integrated industry…The use of citrus pulp for animal feeding was found to be an effective way to decrease waste output.”
PubMed http://www.ncbi.nlm.nih.gov/pubmed/7790589 has an abstract, “Quantity and economic importance of nine selected by-products used in California dairy rations”, that includes University of California, Davis dairy cattle nutritionist professor E.J. DePeters as an author. The by-products include almond hulls, dried beet pulp, wet brewers grains, wet citrus pulp, pressed citrus pulp, wet corn gluten feed, corn gluten meal, whole cottonseed, and rice bran; no doubt many vegetarians and “vegans” are consumers of the primary products of that plant agriculture.
Going forward, people have the option to consciously choose to have smaller-size families to lower one’s demand on finite resources, including fresh water. California has nearly 39 million people in this drought (http://quickfacts.census.gov/qfd/states/06000.html) while it had just ~23 million (http://www.census.gov/popest/data/state/asrh/1980s/tables/st7080ts.txt) during the late 1970s drought.
“Addressing the water crisis isn’t necessarily as simple as going more-vegetarian or quasi-vegan (no one is 100% vegan given the widespread interplay of animals with food production and society in general).”
You are right, essentially no one is 100% vegan (one need only count the insect parts in wheat flour or fruits to confirm this…see the first comic on the site my handle links to), but none of your arguments suggest that a vegetarian diet would not be an appropriate response (indeed http://waterfootprint.org/en/ suggests that it is the single most effective thing that most consumers could do). Of course your final suggestion of reducing population by reducing family sizes is sound, one could imagine various externalities that could make implementation difficult (as one could with the wide-scale implementation of vegetarian diets).
The extent to which animal agriculture is productively coupled with plant agriculture isn’t obvious to me. We tend to go about finding new uses for ag waste products all the time, we don’t necessarily have to put them through animals. Soy oil is essentially a giant byproduct of beef production (and we put it into all sorts of non-essential things like salad dressings, potato chips etc.). In short it isn’t clear hat the net benefit of running plant agriculture byproducts through animals is net positive (according to some sensible metric) over simply not having the animals in the first place. The citrus pulp example is interesting but I can’t get the paper cited (which looks at the total citrus lifecycle), I suspect the net benefits are relatively small.
But perhaps we are moving away from water here. The two important points that are worth clarifying here (I think) are:
1)Are vegetarian diets effective methods of reducing one’s water footprint? Is the entire drought debate perhaps more honestly cast as one about how much money does animal agriculture have to pay for water?
2)Does the http://saveourwater.com/ website offer an honest perspective on the drought and effective methods for individuals to reduce their water footprint?
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