CHEMICAL-PROPERTIES OF SOILS WHERE PALM TREES GROW IN VENEZUELA

A study of soil chemical properties of eleven soils present in different geographycal locations where palm trees (Copernicia tectorum) grow in Venezuela gave the following relevant results: 1) ten soils have at least one layer with exchangeable Mg higher than exchangeable Ca (Mg/Ca=1.00; magnesic layer); 2) eight soils have at least one layer with more than 15% exchangeable Na (sodic layer); 3) ten soils have layers with predominance of Na+Mg in the exchangeable complex (Na + Mg =50%, sodic-magnesic layers); 4) very acid soil pH values (3.75 to 5.00) on the soil surface layers increasing markedly (even to alkaline values) with depth; and 5) all profiles have very low available P values. The common occurrence of these rather unusual chemical properties, especially the first three ones on most of these soils were considered as evidence of their role as fundamental edaphic factors on palm tree adaptation and distribution. These results also indicate that, besides the already described soil physical (high clay content, slow permeability) and environmental conditions (seasonal flooding and drought, and yearly burning), unusual soil chemical properties seem to be also involved with the ecological conditions associated with the presence of palm trees. © 1990, Taylor & Francis Group, LLC. All rights reserved.