Cadillac Desert_ The American West and Its Disappearing Water - Marc Reisner [300]
“When you apply irrigation water,” says van Schilfgaarde, “it has to go somewhere. If it drains back off into the river, quickly, then that’s fine. If it drains down to an underlying aquifer, fine—at least for a while. If it doesn’t drain or drains too slowly, then you have problems. Salts build up in the root zones. The soil becomes waterlogged. Ultimately you can damage the structure of the soil, ruining it forever. So you have to get rid of it. How? Where? These are tremendous problems in places with lots of poorly drained land that apply tens of millions of acre-feet of water per year, like the American West. Basically, you can take the macro or the micro approach. You can build big drain systems, desalination plants, and so on, but you are still left with saline wastewater or pure salt to dispose of. Or you can tune your crop mix and your irrigation system to the reality of poor drainage and saline water and keep the problem at bay. That is what we have been doing here, with considerable success. I keep telling people this but they don’t want to listen to me.”
“Here” is the Department of Agriculture’s Salinity Control Laboratory, of which van Schilfgaarde was then director. It sits in the shadow of a hulking butte near the city of Riverside, California, surrounded by the very last agricultural land in the Los Angeles Basin. Sixty years ago, this was, acre for acre, the richest farming region in the world. Los Angeles County led the nation in farm income. Today, the main crop in the basin is tract housing. Displaced by twelve million people, agriculture moved eastward and northward into the San Joaquin Valley, which has one of the worst drainage problems in the world.
“Salinity is the monkey on irrigation’s back,” says van Schilfgaarde. “The good water goes up in the sky and the junk water goes down, so the problem gets worse and worse. Victor Kovda of the University of Moscow says the amount of land going out of production due to salinity now surpasses the amount being brought into production through new irrigation. In this country, we have lost a few tens of thousands of acres—actually a few hundreds of thousands if you include the Wellton-Mohawk Project in Arizona, on which we later spent a fortune in order to bring salted-out land back into production. But that figure is projected to increase drastically in the decades ahead. The problem is an abstraction to most people, like projections of declining oil reserves were back in the 1960s. If you want to see how bad it can get, go to Iraq.”
Thousands of years before the birth of Christ, the Sumerians in the Fertile Crescent were already getting some experience with salinity firsthand. Counts of grain impressions in excavated pottery from sites in what is now southern Iraq—pottery that has been carbon-dated back to 3500 B.C.—suggest that at the time, the amount of wheat grown was roughly equal to the amount of barley. A thousand years later, wheat production had dropped by 83 percent. It wasn’t that the Sumerians suddenly developed an insatiable craving for barley; they were forced to switch because wheat is one of the least salt-tolerant crops. Between 2400 B.C. and 1700 B.C., barley yields in Sumeria declined from twenty-five hundred per hectare (a highly respectable yield even today) to nine hundred liters per hectare. Not long afterward, massive crop failures began. “Sodium ions tend to be absorbed by colloidal clay particles, deflocculating them,” reads an article in Science magazine from 1958—the first authoritative report linking the demise of Sumeria to salt. “[This] leaves