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o SALINITY MANAG~MENT OPTIONS FOR THE COLORADO RIVER ~ Phase I. Damage Estimate" and Control Program Impacts. 00 0) Subtitle: Agricultural Consequen~es. ~ A. IMPERIAL VALLEY, CALIFORNIA The salient reservations of each of many possible approaches to predicting the agricultural ~onsequences of increasing salinity has been thoroughly re- viewed by Young, Franklin, and Nobe (1973). Their suggestion was that data be sought in the areas being studied to obtain a better estimate of the declination of crop yield as a function of Increasing salinity. Without In situ comparisons of the conductivities of soil and irrigation water large discrepancies can entel' the approximations. Bernstein (1962) states, "In an ideally drained and irrigated soil, the electrical conductivity of the saturation extract could approximate half the value of the electrical conductivity of the irrigation water as a lower limit, because the saturation percentage of a soii is approximately twice the field capacity. At the United States Salinity Laboratory, this relationship generally obtains in artiflcally sa Ii n i zed plots i rr' i 9ated throughout a season wi th water of a <Jiven salinity. Under commercial conditions, sllch idG,dly restd,.tcd salinity levels rarely occur. Even in exec] len:, cit,.us orchards, the electrical con- ductivity of the applid water at one depth or another in the root zone (Chapman and Harding, 1956). Under less favorable c.onditions with poorer management, much highet' ratios develop." A'number of things may contribute to the variation noted by Bernstein, but drainage is the key. Drainage is closely associated with soil texture. Extremely high salinity irrigation water has been used by Cavazza (1968) in Italy. Reports indicate t:,at brackish water of 3% salinity has been used in pugtia and Lucania. A maximum tolerance of 8% is reported for tomatoes. Tlli s value is in excess of 20 mmho and much higher than utilized in the United States. The key to this ability to use high salinity water is the sandy textured soil which is well drained.. In the same publication Boyko (1968) reports on the desert garden of Eilat where 2,000 to 6,000 mgll water is being used on sandy soils for a host of plant species. Van Hoorn et al. (1968) using water of 4-5 gll report excellent yields of wheat, maize, sorghum, alfalfa, cotton, beans, asparagus, tomatoes, and melons in Tunisia on a well drained soil. Durand (1956) established :on irr.jgatlon water evaluation system which incorporates . 7