ABSTRACTSoluble Na, expressed in terms of sodium adsorption ratio, SAR, and its relationships to exchangeable sodium ratio, ESR, and to exchangeable sodium percentage, ESP, were examined in 31 surface soil samples from the Nile Delta. Empirical equations for SAR-ESR and SAR-ESP relationships were developed and compared to those obtained by the U.S. Salinity Laboratory Staff and by Bower. Excellent agreement was observed between all equations employed and between them and the actual data. Proportions of exchangeable sodium predicted by the U.S. Salinity Laboratory equations were, however, lower than the observed values at the low and at the high levels of SAR. The difference was, nevertheless, within 5 units of ESP, and does not seem to impair the validity of the SAR concept.
Soluble Na, expressed in terms of sodium adsorption ratio, SAR, and its relationships to exchangeable sodium ratio, ESR, and to exchangeable sodium percentage, ESP, were examined in 31 surface soil samples from the Nile Delta. Empirical equations for SAR-ESR and SAR-ESP relationships were developed and compared to those obtained by the U.S. Salinity Laboratory Staff and by Bower. Excellent agreement was observed between all equations employed and between them and the actual data. Proportions of exchangeable sodium predicted by the U.S. Salinity Laboratory equations were, however, lower than the observed values at the low and at the high levels of SAR. The difference was, nevertheless, within 5 units of ESP, and does not seem to impair the validity of the SAR concept.
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