A growing population coupled with diminishing fresh water supplies should force major changes in the way the world's farmers water their crops in the coming decades, a recent study recommends.
ALBANY, N.Y. A growing population coupled with diminishing fresh water supplies should force major changes in the way the world's farmers water their crops in the coming decades, a recent study recommends.
Since agriculture uses about 70 percent of the world's fresh water every year, farming should be the focus of intense conservation efforts, said David Pimentel, a professor at Cornell University and primary author of the study published in the October issue of the journal BioScience.
"We in the U.S. waste a lot of water in contrast to other people," Pimentel said. "Agriculture is going to have to give up water as the population grows. States like California, Colorado, Texas and Nebraska are going to have to make some major changes."
The study said farmers should use water-conserving irrigation methods combined with water and soil conservation practices to minimize run-off. The study also suggests governments eliminate water subsidies to farmers to encourage more efficient water use, work to reduce water pollution and protect forests and wetlands.
In parts of Arizona, water from major aquifers is now being withdrawn more than 10 times faster than it can be recharged by rainfall. In California, agriculture accounts for about 3 percent of the state's economic production but consumes 85 percent of the fresh water.
The United Nations estimates world population will rise to 9.4 billion by 2050 from about 6.3 billion now. The increasing demand for water is already causing problems.
Pimentel cites the massive Ogallala aquifer, under parts of Nebraska, South Dakota, Colorado, Kansas, Oklahoma, New Mexico and Texas, that supplies water to a fifth of all irrigated land in the country. The underground water source has dropped 33 percent since 1950 -- half the volume of Lake Erie, said Sandra Postel, director of the Global Water Policy Project in Amherst, Mass.
Similar problems are happening worldwide, from the Chenaran plain in northeastern Iran to Guanajuato, Mexico. Of particular concern is Asia, home to 60 percent of the world's population, but only 30 percent of its fresh water. Postel says water efficiency will have to double to meet future needs.
"The pace of the problem is proceeding faster than the pace of the solution," Postel said. "It takes a while to overhaul things and I don't see policy makers taking these issues seriously enough that they get corrected."
"We are using tomorrow's water today to meet our food needs," she said.
By 2050 "water will to be the most critical resource issue we face in the entire world," said Bob Stallman, president of the American Farm Bureau Federation and a Texas-based rice farmer. "Frankly, I think wars will be fought over water. There are already border disputes in some parts of the world between countries over water."
Stallman said farmers have made efforts to conserve water in the past two decades.
Much of the problems stem from current methods of irrigation. Sprinkler systems lose much of their water through leaks and much of the water applied by that method or flood irrigation ends up as runoff.
Farmers should turn to drip irrigation, a system that pipes water directly to plants, or better sprinklers that can cut water use by 50 to 80 percent, Postel said. In the Texas high plains, more efficient systems are now easing the strain on the Ogallala aquifer, she said.
But drip systems could be at least 30 percent more expensive, may require more energy to run and require clean water to prevent clogging.
Government subsidies only exacerbate the problem. The United States provides $2.5 billion to $4.4 billion in annual construction subsidies for irrigation, the study said. Worldwide, governmental water subsidies from 1994 to 1998 totaled about $60 billion.
Pimentel argues that cutting those subsidies would encourage farmers to conserve.
Gary Margheim, special assistant to the chief of the National Resources Conservation Service, said the 2002 Farm Bill provided $17 billion over 10 years for water conservation programs.
This past year, $60 million has been spent to help farmers schedule irrigation more effectively, install drip irrigation or low-pressure sprinkler systems and eradicate water-sucking invasive plant species in the southwest.
"The public may not realize how much is being done" or understand the magnitude of the problem, Margheim said.
Adding to the problem in the United States is a population shift from rainfall-rich areas like the Northeast to warmer, drier areas in the South and Southwest.
Pimentel sees a potential shift back to areas like the Pacific Northwest or the Northeast where agriculture is sustained mostly by rainfall, not irrigation.
"This is why I'd like to see us protect any agricultural land in the Northeast, because we're going to need it in the future," Pimentel said.
Pimentel suggests consumers can help reduce water usage by buying locally produced crops instead of those grown far away and by switching the types of foods they eat.
For the Northeast, that means eating cabbage instead of lettuce grown in California or choosing chicken and pork over beef. It takes 3,500 liters of water to produce one kilogram of chicken, but 43,000 liters for the same amount of beef, he said. Rice needs about 1,600 liters of water per kilogram, but corn requires just 650 liters.
"There are lots of things individuals can do to change food habits," he said.
Source: Associated Press