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<br />J.D. RHOADES ET AL.
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<br />Fig. 2. Levels of Boil salinity in the seedbed at time of germination of each crop in the "block"
<br />rotation.
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<br />grown using drainage water for irrigation or on the land where it had previously
<br />been used. These quality data are given elsewhere (Rhoades et aI., 1988a).
<br />Figures 1 and 2 show the soil salinity during the field trials at various times
<br />in the "block" rotation to illustrate how salinity increased from irrigating the
<br />cotton crops with drainage water and was lowered by the pre-irrigation of cot-
<br />ton and the irrigation of wheat and alfalfa with Colorado River water. More'. .
<br />detailed data on soil salinity and sodicity (including that for the "successive"
<br />rotation) are given elsewhere (Rhoades et aI., 1988b). These data are given to
<br />demonstrate that soil salinity was kept within acceptable limits for seedling
<br />establishment imd the subsequent growth of the crops grown in the "block"
<br />rotation when the recommended strategy was employed. These results ob-
<br />tained under actual farming' conditions support the practicality of the recom-
<br />mended cyclic crop and water strategy to facilitate the use of saiimi waters for
<br />irrigation.
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<br />SUMMARY AND CONCLUSIONS
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<br />Rational water assessment procedures indicate that waters of higher salin-
<br />ities than customarily classified as suitable can be used effectively for irrigating
<br />selected crops with conventional methods of management. Customary water
<br />quality standards appear to have been based on the availability of good quality
<br />water and are too conservative. Worldwide literature documents that relatively
<br />saline waters can be used for irrigation. The use of saline waters for irrigation
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