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.... 00 N ~. Hybrid Grass May Help Reclaim Salt-Laden Land Reprinted from the JoumoJ of Soli & Water Consef1larlon, May.June /986. Vol. 41, No.3. A hybrid grass grown for livestock feed also acts as a soil cleanser and could help reclaim millions of acres of salt-laden soil in the West, according to an Agricultural Research Service scientist. Salt. or sodium, that accumulates in soil can form a crust on the soil surface. impeding crop growth. But the new grass, a cross of sorghum and sudan-grass, releases a high level of carbon dioxide into the soil, which frees the salt so that rainfall or irrigation water can leach the sail out of the soil, according [Q Soil Scientist Charles Robbins of Kimberly, Idaho. The hybrid grass grows to 11 or 12 feet and produces about 25 tons of grass per acre. It is drought-resistant and can be used for livestock feed and silage in low rainfall areas. Robbins' studies indicate the grass could be used to reclaim millions of acres of salt.bound soils in the arid West, parts of the northern Great Plains, western Canada, and similar regions throughout the world. In one tesl, on a soil so high in sodium content that no crop of value could be grown, the grass averaged 20 tons per acre. The grass, says Robbins, might also help cut costs of applying gypsum to reclaim soil. In irrigated regions farmers must apply 10 to 20 tons of gypsum per acre at a cost of $65 to $70 a ton. "We are getting surprisingly better results by planting the hybrid grass than we got by applying gypsum," Robbins said. Visitors Tour Grand Valley Stage One On April 15, 1986, 22 people from India were given a field review of Stage One, the completed portion of the Grand Valley Unit, Colorado. The Indians are touring the Western United States to study waterlogging, drainage, and salinity control. One report estimates that 35 percent of India's irrigated land is seriously saline. Tracking Salty Soil Excerpted from an article by Dennis Senft, Albany, California, in the publication Agricultural ResHrCh, U. S. Department of Agriculture, Agricultural Research Serllice, January /986. 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 100 yards into an adjoining field. There he shovcs the probe six inches into the soil and pushes a button to automatically record soil salinity and exact location in the field. When severaJ hundred such measure- ments 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, analyzes the information and prints a map that indicates areas where yield~reducing salts are accumulating in farmers' fields. Agricultural Research Service 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 tech- nique portrayed above. The USDA's Soil Conservation Service has contributed $ 1 00,000 this year to help make such soil salinity mapping possible, 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. One report estimatcs 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 saits. "Estimates are educated guesses," says Jan van Schilfgaarde, former director of the U.S. Salinity Laboratory, Riverside, CA, "but until we develop ways to monitor the degree of increasing salinity, I won't argue with anyone who says we have a very serious problem both here and overseas." Long-term corrective action is needed to protect irrigated agriculture, but first we need to be able to detect the onset or problems and to predict where they will occur:' says ARS soil scientist James D. Rhoades, Riverside. Rhoadcs says salinity measuring is currently done in laboratories, and each sample can cost up to $25 with several dozen needed for each field. Such expense is prohibitive for mapping large areas. "The sampling technique and maps we are developing will eliminate the major need for soil sampling and laboratory analysis. Cost figures haven't been calculated yet, but if we can get the system automated, it should cost a mere fraction compared with present tech- niques. " Maps that minimize the need for direct measurement use computer overlay tech- niques and can be likened to maps in some geography text books. Geographic features are printed on one page and additional information, such as how boundaries have changed over lime, is printed on individual overlays made of clear plastic. In this case, each overlay contains information on one factor that can contribute to salinity in soil. These factors include water table depth, soil permeability, leaching fraction (the amount of excess irrigation water applied to leach salts below the root zone), and ground-water salinity. A composite of these factors defines areas of probable salinity development. Several thousand pieces of information can be entered into the computer for each map. Then computer programs written by Dennis L. Corwin, formerly with ARS, manipulate the information. The programs analyze values assigned to each salinity factor. When these values exceed an assigned number, the computer indicates a potential trouble area. Armed with these maps, farmers and growers will be able to locate areas on their land where salt problems are likely to occur. They can then change the way they farm to avert or reduce damage. Such damage, unchecked, would not only put farmers out of business, but could