Wheat and barley seedlings growing in pots in a greenhouse, with a non-saline sandy loam soil were irrigated, by saline waters, $1, $2, and $3, having EC i = 3, 9, and 15mScm -1, respectively. Each solution has three potassium concentrations, K~ = 6, K 2 = 11, and K 3 = 16meq L -l, and all incorporated N (90mgL -l) and micro-nutrients. Irrigation was provided to realize 0.2 and 0.5 leaching fractions (L).At maturity, dry matter of plant tops (Y), grain yield (G), and evapotranspiration (ET) of both crops responded significantly to the S, L, and K treatments. There were different interactions, however, between the crops indicating some effect of plant species. In both, a decrease in Y with increasing salinity was associated with a corresponding decrease in ET. In the most saline S 3 treatments, where the available water to plants was the lowest, an ample K supply produced substantial improvements in salinity tolerance of both crops. Under these conditions, changes in Y and ET were independent of each other. Increasing K supply, reduced the rate by which Y decreased with respect to S. Barley accumulated dry matter more efficiently (in terms of ET y -l , g per g) particularly under L = 0.2. This efficiency for both crops did not respond to the water salinity but rather to the potassium concentration of the waters.The whole experiment was also carried out under two levels of phosphorus application (35 and 70 mg P kg i soil). Neither growth nor water-use efficiency were significantly affected by the higher rate of phosphorus application.

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Abstract--The occurrence of palygorskite in some Tertiary sediments in eastern Saudi Arabia was studied. Mineralogical and chemical analyses were made of samples from two sections several meters thick from the Umm er Radhuma and Dammam Formations of Paleocene and Eocene periods, respectively. Layers of shales were observed within the sections of the dolomitic-calcitic limestone of the Umm er Radhuma Formation and of the dolomitic limestone of the Dammam Formation. After treatment for carbonate removal the shales consisted of more than 95% clay-size particles, most of which were <0.2-#m in size. Palygorskite was the main constituent of some of the shales, with minor amounts of gypsum, soluble salts, and carbonates. The association of gypsum and other salts with palygorskite in the shale suggests that palygorskite formed in closed-basin environments. The presence of palygorskite and the absence of other minerals in the clay fraction of the limestones also suggests that the palygorskite formed under marine conditions.

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