html xmlns="" xml:lang="en" lang="en"> From the archives: Down with rice.

Wednesday, October 24, 2007

Down with rice.

An anonymous said this in the comments, and it prompted me:
California also grows *rice* which is another water hungry crop.

OK, I hear this a lot, and I understand the rough take. Rice! So tropical! Makes one think of monsoon fed flooded fields! So water intensive! In arid California! Rice in California sounds like a bad plan.

I’ll defend growing rice in Calfornia, though, especially in the Sacramento Valley. The Sacramento Valley is a great rice growing region, primarily because of its clay soils. My rough understanding is that the Sacramento Valley used to flood every winter, nearly over the entire valley floor. The floods would drain slowly for months, but during that slow recession, fine silts had time to settle and form a clay layer. I can vouch that the soils are clay-ey and sticky. Walking through a wet field gets you a five or six inch thick clump under your each boot. Because of these clays, you can hold water in a rice paddy indefinitely. You can’t grow much else on them.

But the water! So much water! Well, yes and no. It is true that rice requires a decent amount of water, about four-ish acre-feet per acre per year. It is also true that you have to manipulate the hydrologic cycle to provide that; there are no half-inch rains twice a week to keep your paddy full. But there is water enough for rice. It just falls in the winter. You have to store it, and release it later, but the climate in northern California provides more than enough water for rice. We’re in a built system now, so we can do that.

Four-ish acre-feet? Isn’t it a lot more than that? It used to be. Until a decade ago, Sac Valley growers grew flow-through rice. They constantly fed water into the top paddy; it trickled through the paddies and out drainage canals into the Sac River. That can use ten to twelve acre-feet (per acre per year) or more. They don’t do that anymore, and the reason has nothing to do with water scarcity. The State Board made them stop. The State Board forced them to hold water in their fields until their herbicides had broken down to some threshold concentration. (Rice growers tout this as environmental dedication now, but they fought it bitterly when the regulation came down.) They’ve been trying varieties of rice, long and short stemmed, to see what they can grow in different heights of water. Rice is no longer a water-guzzler.

I like some things about rice in the Sac Valley. In some ways, it mimics the cycle of flooding up large stretches of the valley floor and draining it slowly (although it pushes it back three months). Rice looks amazing. I swear, rice is the reference green. There is nothing greener than rice. It shimmers green, with greener pulses. All spring you think that the young rice sprouts are the greenest thing you ever saw and come summer, it darkens into more green. Rice fields smell good. White egrets look beautiful against a rice field. Rice uses soils that probably couldn’t grow any other agricultural crops. California grows very good rice; high yields, very high quality. Ricelands are also preserving a sink capacity that might otherwise have been lost; we will need places to spread big flood waters and rice fields are a good candidate.

So the big problem with rice these days isn’t the water use. The current environmental problem caused by rice is rice straw. Used to be, rice growers drained their paddies, harvested their rice and burned the straw. The smoke used to fill the valley, block out the sun. The Air Board put a stop to that, and ever since, growers have been trying to find a way to get rid of rice straw. The Air Boards offers permits for some limited burning. Growers have been selling rice straw to fill rolls to use on construction sites to prevent sediment run-off. There is talk of using the rice straw for biofuels or methane production. People have suggested using rice straw to replenish the peat that blows away when Delta islands are farmed. If you let the rice straw sit under water all winter, it (mostly) decomposes, but rice growers fear cross-year rice diseases. That requires a second flood-up for the year, of de-comp water. That has been messing with water district canal maintenance regimes. The problem isn’t solved yet.

Anyway, a long digression about rice. Basically, I am not opposed to growing rice in California. It no longer uses an extraordinary amount of water, and has some nice features. In keeping with my belief in eating locally, I do wish since northern California is an excellent rice-growing region, we were also a rice-eating culture. But that’s a different post.

A side note for Tom:

One of the best things about rice is that it uses so much jargon. Another plus! We love jargon! Since you asked for a glossary:

Rice is grown in checks. (I called them paddies, because you are probably used to the term rice paddy.) But here, the whole field, tens of acres surrounded by a berm and filled with water to grow rice, is a check.

Water fills the check through a check structure (something in the canal to divert water into the check) or through a rice box. A rice box is embedded into the berm at the top of the field. It is, roughly, a rectangle of known width (preferably standardized throughout the district) with flashboards in it. You pull the flashboards in the spring for the flood-up and measure (not very precisely) the flow through the rice box by knowing the height of the water over the top flashboard.

I forget all the rest of the jargon for rice. When the rice itself forms in seed tassles, it is ‘heading up’. I think you want to harvest right before the “shatter”. If I think of more, I’ll add it.


Anonymous Mitch said...

Oooh yeah, baby, that's right, uh-huh. Just like that. Oh yeah.


Rice looks amazing. I swear, rice is the reference green.

For anyone who hasn't seen it yet:

There is talk of using the rice straw for biofuels or methane production.

Okay, now you're really getting me going. How much more expensive does oil have to be before cellulase production is economically justified? Actually, if we could guarantee that oil stays as expensive as it is, that would probably be enough. What kind of total annual mass of cellulose are we talking about, here?

We don't have to replace all oil overnight, we just have to make up the difference between demand and the slow decline of supply. The thermodynamics are there, in the form of sunlight and land that can support the growth of various kinds of feedstocks, plus ag waste like rice straw, wheat straw, sugar cane bagasse, corn stover, etc. The economics are not quite there yet. But it's slowly transitioning from a research problem to a development one.

7:00 PM  
Blogger Mandatory Vacation said...

For those of us not up on the latest farming figures, what is considered "good"? How does rice compare to other things that could grow in the area?

7:53 PM  
Blogger emile said...

Straw bale construction is also a pretty nice candidate for rice straw usage.

10:14 PM  
Anonymous Anonymous said...

Question from a guy who's never farmed a day in his life. Why is water measured in acre-feet per acre per year? Why not... feet per year?

10:42 PM  
Blogger Megan said...

Said out loud, it is actually acre-feet, or feet. "I put four feet on my vines last year." "My tomatoes? Three and a half acre-feet."

If I heard just acre-feet, I would assume the rest - per acre, per year. All I really want to know is how high the water stacked, because I have a comparative sense of those. I was being overly precise in the post, because I was afraid of getting called on my units or confusing someone.

You're right though. Feet is what people would say out loud. Or acre-feet.

10:51 PM  
Anonymous Anonymous said...

Comparison to other crops is useful. Irrigated pasture and alfalfa are in the 4+ foot range as well. Those plus rice are on the high end. For visualizing an acre-foot, think of a football field including end zones under water a foot deep (how fun does that sound?); about 326,000 gallons.

Rice is neat. I prefer the old days before laser-leveling, when the rice dikes matched the natural contour of field (so flat from the ground, but so curvy from the air). The seeding by airplane is really fun to watch. When CA rice growers get together for the annual meetings of their marketing pools, they eat sushi.

Question for Megan: if we were to ignore pesticide residues, what are the real issues with rice using 12+ feet of water, like the old days. A large percentage flows out of the fields, right. Sediment loading? Temperature change? Time shifting of flows?


7:59 AM  
Blogger Tom said...


9:17 AM  
Anonymous Francis said...

Well, this took a LOT of finding. But the California Department of W*ter R*sources has a Division of Pl*nning and Loc*l Ass*st*nce, which collects Annual Land and Water Use data, which includes Crop Water Use, which includes Applied Water for the years 1998-2003.

ahem. this is the link to the 2003 Crop Water Use, Applied Water page. Downloading the "county" file, one discovers that in Sacramento County, rice got 5.90 acre-feet of water per acre per year. Alfalfa and pasturage were also above 5 afa per acre.

6:57 PM  
Blogger David Zetland said...

Note also that rice grows best on muddy land, which is not good for crops that need deep roots and drainage.

On thing that still annoys me about rice is that you get a CA TAX DEDUCTION for buying rice straw. WTF? I want a deduction other CA products, like wine (or weed!)

11:14 AM  

Post a Comment

<< Home