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D. Research and Demonstration f'\:) W 00 {J> USDA research and demonstration activities are vital to the continued development and improvement of new water management techniques and technologiea which are beneficial, to salinity control. The ARS, through the U.S. Salinity Lab at Riverside, California is involved in, two 'research efforts related to the use of saline or brackish water (saline ,irrigation and drainage return flows) and the measurement of soil salinity with an electro-magnetic probe. ;:;~~:jr?~ .......:. In the Imperial Valley, a large field experiment was ,initiated in January 1982 in cooperation with Imperial Valley Irrigation and Drainge District, California Division of Water, University of California, and private landowners, to'develop management strategies for reusing drainage flow water, now wasted to the Salton Sea, as irrigation water. Use of such water would permit, in principle, a significant reduction in diversions to Imperial Valley without reduction in area irrigated, and thus would free Colorado River water for alternative uses. A 40-acre area has been leveled into two 20-acre fields, each divided in roughly l-acre plots. Two different cropping patterns are planned (wheat/sugar beets/lettuce and cotton/cotton/wheat/alfalfa) ,to assess riot only the use of brackish water for tolerant crops, but also the potential of "rapid" shifts between growing salt tolerant and salt sensitive crops. CoJorado River water and drain water are used sequentially as needed; they are not mixed. On half the area, a crop was followed by beets, as planned; and a cotton crop was grown on the other half. Currently the cotton crop has matured and the beet crop is in the field. It is too early to present meaningful results, but experience co date is "on target". -.... ::~~~;:;i;> The ARS, working in cooperation with the BR, also has' a project underway to develop a nondestructive probe that can measure soil salinity status in a manner analogous to the soil water content measurement with a neutron probe. The probe, an adaptation of a commercially available ,instrument that measures, soil salinity of a profile from the surface, would provide, more 'accurate and depth-specific'data with high repeatability over time. The developcent has 'been set back by electronic difficulties encountered by a contractor, but recent results are promising. In the Uinta Basin and Grand Valley projects, far@ers with cablegation (automated) irrigation systems report that additional irrigations do not appreciably increase their irrigation costs. Consequently, they apply less total water than when they hand set their irrigations. Limited data collected to date by ARS and Colorado State University (CSU) indicate that this type of irrigation system increases yields and substantially decreases deep percolation. More data are needed to quantify the results of automation. Measuring and recording equipment will be needed to accomplish this objective. The change of policy in Grand Valley 'which made automation a voluntary rather than compulsary condition for cost-sharing of irrigation improvements resulted initially in the installation of fewer automated systems. However, the excellent performance of some of the new automated systems developed by ARS and SCS, and satisfaction of their owners, are developing a situation where automation will be more widely accepted on its own merits. . .;. .' 18