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Tracking Salty Soil, Saving Fresh Water
| Article
# : |
10080 |
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Section : |
NATURAL SCIENCE
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| Issue
Date : |
4 / 1986 |
1,883 Words |
| Author
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Dennis Senft
Dennis Senft has been reporting on agricultural research for
the U.S. Agricultural Research Service at Albany,California,
for fifteen years |
A pickup truck pulls off the highway and stops. A high school student gets out, removes a probe which is attached by wires to a backpack data recorder, swings the equipment over his back, and walks about one hundred yards into an adjoining field. There he shoves the probe six inches into the soil and pushes a button to automatically record soil salinity and the exact location in the field.
When several hundred such measurements have been recorded, the young employee returns to the local irrigation manager's office and electronically transmits the information into a computer. The computer, no larger than some home models, analyses the information and prints a map that indicates areas where yield-reducing salts are accumulating in farmer's fields.
Agricultural Research Service (ARS) scientists have developed the measuring probe, now commercially available, and the computer programs. They are now evaluating ways to make the large-scale collection of data economical, perhaps much like the technique portrayed above.
The United States Department of Agriculture's (USDA) Soil Conservation Service has contributed $100,000 this year to help make such soil salinity mapping possible.
Salinity, and the resulting decreased crop yields, has been a problem for irrigated agriculture for at least 4,000 years. Mesopotamia, an area between the Tigris and Euphrates Rivers in what is now Iraq, once flourished with agriculture and civilization. Salinity associated with irrigation slowly doomed the area--today a vast semidesert supporting only half the population it once did.
Salinity still plagues irrigated lands. Some of this country's most productive farmland is being lost to this natural phenomenon that has been accelerated by irrigation. California has 8.6 million acres of irrigated land and about half, 4.5 million acres, is affected to some degree by salinity. Similar problems are occurring throughout the western United States.
Some estimates for foreign countries are particularly bleak. For example, one report estimates that 35 percent of India's irrigated land is seriously saline and that one-quarter to one-half of South America's irrigated acreage is adversely affected by salts.
"Estimates are educated guesses", says Jan van Schilfgaarde, former director
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