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...'s total food and fiber, is adversely affected by soil salinity on roughly half of all irrigated soils (totaling about 250 million ha) with over 20 million ha severely affected by salinity worldwide (=-=Rhoades and Loveday, 1990-=-). To prevent the accumulation of excessive soluble salts in irrigated soils, more water than required to meet the evapotranspiration needs of the crops must pass through the root zone to leach excess...

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...ntional salt-tolerance parameters (i.e., intercept and slope) for alfalfa, wheat, and lettuce are: 2.0 dS/m and 7.3% per dS/m increase in ECe, 6.0 dS/m and 7.1%, and 1.3 dS/m and 13.0%, respectively (=-=Maas, 1990-=-). Alfalfa is classified as a moderately sensitive crop, wheat as a moderately tolerant crop, and lettuce as a moderately sensitive crop. Thus, the chosen rotation will require a relatively high degre...

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...ty from exceeding a level that would significantly reduce crop yield under steady-state conditions with associated good management and uniformity of leaching (U.S. Salinity Laboratory Staff, 1954 and =-=Rhoades, 1974-=-). Reclamation of inherently saline soils, or of soils allowed to salinize through underirrigation and other similarly inappropriate forms of management (e.g., by fallowing soils for extended periods ...

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...ur study's objectives: (i) the traditional LR model originally developed by the USDA-ARS, U.S. Salinity Laboratory (U.S. Salinity Laboratory Staff, 1954) and modified by Rhoades (1974), (ii) WATSUIT (=-=Rhoades and Merrill, 1976-=-), (iii) water-production-function (WPF) model (Letey et al., 1985), (iv) TETrans (Corwin et al., 1990), and (v) UNSATCHEM (Šim�nek and Suarez, 1994). These models were specifically selected because t...

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...ratory (U.S. Salinity Laboratory Staff, 1954) and modified by Rhoades (1974), (ii) WATSUIT (Rhoades and Merrill, 1976), (iii) water-production-function (WPF) model (Letey et al., 1985), (iv) TETrans (=-=Corwin et al., 1990-=-), and (v) UNSATCHEM (Šim�nek and Suarez, 1994). These models were specifically selected because they reflect a spectrum of categories of models ranging from steady-state to transient models and from ...

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...t. However, data obtained from controlled studies carried out in test plots utilizing relatively uniform soil conditions and optimal irrigation and crop management were available (Bernstein, 1974 and =-=Maas and Hoffman, 1977-=-). These controlled studies related the response of many crops to average root zone soil salinity in terms of the EC of the saturation extract, ECe (dS/m), which is approximately half that of the soil...

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...properties was sought so that the estimated LRs from the models could be compared. A data set was developed from available data sources representative of California's Imperial Valley (for details see =-=Rhoades, 1999-=-). To estimate the LR for the entire Imperial Valley, one must consider the crop sequence grown and associated rooting depth on each and every individual field. Even if known, the combinations would b...

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...ty from exceeding a level that would significantly reduce crop yield under steady-state conditions with associated good management and uniformity of leaching (U.S. Salinity Laboratory Staff, 1954 and =-=Rhoades, 1974-=-). Reclamation of inherently saline soils, or of soils allowed to salinize through underirrigation and other similarly inappropriate forms of management (e.g., by fallowing soils for extended periods ...

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...a/wheat/lettuce. Imperial Water District reports and data in Circulars 104-F and 104-V of the University of California Cooperative Extension for the Imperial Valley were used to develop the schedule (=-=UCCE, 1996-=-a and UCCE, 1996b), together with personal communications with Kalid M. Bali (Imperial Valley Farm Advisor, Irrigation/Water Science) and Marvin Jensen (Agricultural Consultant to the Bureau of Reclam...