Sodium adsorption ratio-exchangeable sodium percentage relationships in a high potassium saline-sodic soil

Summary

Exchangeable sodium percentage (ESP) and sodium absorption ratio (SAR) values were obtained from 692 soil samples and their saturation extract solutions. All samples were from a Declo silt loam (coarse, loamy, mixed, mesic, Xerollic Calciorthids) phase that was saline-sodic and very high in potassium (K). Some samples contained as much as 80 meq K/1 in the saturation paste extract. In those samples where the Na : K ratio was less than 4 : 1 the measured ESP was considerably lower at a given SAR than is usually observed in high Na soils. As the soluble salts were leached from this soil in lysimeters and under field conditions, with or without Ca amendments, the soil did not become sodic nor have decreased infiltration rates when irrigated with low salt water (200 μunhos/cm). The exchangeable K was more tightly held on the exchange sites than were Ca, Mg, or Na, thus reducing the high Na effects.