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VI. Innovative Features of the Project Salinity Mapping Technology: Salinity problems start when previously non-saline soils become saline as a result of irrigation. Salts begin to accumulate within the soil profile because all waters contain some dissolved salts. The accumulation occurs when salts are left behind as crops take up water. With continued salt accumulation, water becomes less available for plant growth. causing lower crop yields. Salinity problems in fields are often difficult to spot before significant crop damage occurs. Typically, saline soils are recognized by the presence of white crusting on the soil surface, spotty crop stands or by irregular plant growth. Historically. field salinity problems have been assessed by taking soil samples and sending them to a laboratory for analysis. There are several limitations to assessing salinity using this conventional technique. To <;ffectively sample a field, several hundred soil samples may be required, particularly for large fields. At 10 minutes per sample. time investment in the field is substantial. Second, it is not uncommon for the cost of analysis to exceed $25 per sample. Third. it is common for laboratory results to take weeks before information is received. Fourth, conventional methods aren't conducive to returning to a field to check and monitor the effectiveness of any management or structural practice on the salinity problem. Techniques to provide inexpensive, accurate and detailed data for large areas have been needed to overcome these limitations for the effective diagnosis, management and monitoring of salinity conditions. Recently. two mobile systems have been developed by Dr. James Rhoades and his staff at the USDA-ARS Salinity Laboratory that can rapidly measure soil salinity. Global Positioning System: Another key to the technology is the use of the Global Positioning System (GPS). Both of these mobile instruments require the precise location of each salinity measurement. The GPS currently is comprised of 16 radio-equipped navigational satellites circling the earth in 12-hour orbits. The receiver automatically collects simultaneous location data from at least three satellites, performs precise triangulation and calculates the exact field position of each salinity measurement. At the field site, the salinity measurement and GPS data are down-loaded to a computer and processed. From the data, the computer program pinpoints for the technician the exact points in the field that will require limited soil sampling to ground truth the salinity measurements. Typically, only four to six soil sampling sites would be required in a 60 to 80 acre field. The Natural Resources Conservation Service in Colorado is currently acquiring and developing a set of equipment and instrumentation patterned after the prototypes developed by the staff at the USDA-ARS U.S. Salinity Laboratory in Riverside, California. This project demonstration site will be used to evaluate this new technology. Once implemented it will' be the first time this technology will be available to Colorado farmers in making more timely and more accurate salinity assessment for better management of irrigated soils. Surge Irrigation: Surge irrigation is a relatively new irrigation technology that is now being recognized as a usable practice in the Arkansas River area. This study will allow area irrigators to observe the effectiveness of surge irrigation as an improved irrigation Best Management Practice under local soil, water and environmental conditions. A final innovative feature of this project is the combined use of irrigation technology and alternative forage species to reduce nitrate and salt loading on the soil and in the runoff water and ground water. Alternative forage crops requiring less fertilizer and irrigation. combined with more efficient irrigation technology can 11