Phosphorus Residual Effect in Andisols Cultivated with Potatoes

摘要

Soils derived from volcanic ash (Andisols) cover an appreciable area of Central and South America. The clay fraction of Andisols is dominated by allophane and imogolite (amorphous, short range ordered minerals) which come from the weathering of pyroclastic material produced from recent volcanic depositions. Research conducted in the last 20 years has demonstrated that humus-aluminum (Al) complexes also play a significant role in Andisol chemical behavior. One of the most important characteristics ofAndisols is their high capacity to immobilize (fix) phosphorus (P) on the surface of the amorphous minerals. This is perhaps the principal chemical constraint of Andisois. It seems that the P fixing capacity varies with the type of clay mineral, affecting the residual value of phosphate applications.