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<br />. <br /> <br />. <br /> <br />D. Research and D~onstration <br /> <br />l'\) <br />o <br />w <br />en <br /> <br />USDA research and d~onstration activities are vital to the continued <br />development and improvement of new water management techniques and <br />technologies which are beneficial to salinity control. The ARB, through the <br />U.S. Salinity Lab at Riverside, California is involved in two research efforts <br />related to the use of saline or brackish water (saline irrigation and drainage <br />retun\ flows) and the measureDlSnt of soil, salinity with an electro-magnetic <br />probe. <br /> <br />In the Imperial Valley, a large field experiment was initiated in January 1982 <br />in cooperation with Imperial Valley Irrigat1on,and Drainge District. <br />California Division of Water, University of California, and private <br />landowners, to develop manageDlSnt strategies for reusing drainage flow water, <br />now wasted to the Salton Sea, as irrigation water. Use of such water would <br />permit,. in prinCiple, a significant reduction in diversioUll to Imperial Valley <br />without reduction in area irrigated, and thus would free Colorado River water <br />for alternative uses. <br /> <br />A 40-acre area has been leveled into two 20-acre fields, each divided in <br />roughly l-acre plots. Two different cropping patterns are planned <br />(wheat/sugar beets/lettuce and cotton/cotton/wheat/alfalfa) to assess not only <br />the use of brackish ~ater fo; tolerant crops, but also the potential of <br />"rapid" shifts between growing salt tolerant and salt sensitive crops. <br />Co~orado River water and drain water are used sequentially as needed; they are <br />not mixed. <br /> <br />On half the area, a crop was followed by beets, as planned; and a cotton crop <br />was grown ou the other half. Currently the cotton crop has meeured, and the <br />beet crop is in the field. It is too early to present meaningful results, but <br />experience to date is "on target". <br /> <br />The ARB, working in cooperation with the Ba, also has a project underway to <br />develop a nondestructive probe that can measure soil salinity status in a <br />menneranalogous to the soil water content: measurement with a neutron probe. <br /> <br />The probe, an adaptation of a commercially, available instrument that measures <br />soil salinity of a profile from the surface, would provide more accurate and <br />depth-specific data with high repeatability over time. The development has <br />been set back by electronic difficulties encountered by a contractor, but <br />recent results are promising. <br /> <br />In the Uinta Basin and Grand Valley projects, farmers with cablegation <br />(automated) irrigation systems report that'additional irrigations do not <br />appreciably increase their irrigation cost$. Consequently, they apply less <br />total water than when they hand set their irrigations. Limited data collected <br />to date, by ARB and Colorado State University (CSU) indicate that this type of <br />irrigation system increases yields and sub$tantially decreases deep <br />percolation. More data are needed to quantify the results of automation. <br />Measuring and recording equipment will be Iieeded to accomplish this objective. <br /> <br />The change of policy in Grand Valley which ,made automation a voluntary rather <br />than compulsary condition for cost-sharing 'of irrigation improvements resulted <br />initially in the installation of fewer autqmetsd systems. However, the <br />excellent performance of soma of the new automated systems developed by AlS <br />and SCS, and satisfaction of their owners,are developing a situation where <br />automation will be more widely accepted on its own merits. <br /> <br />18 <br />