EVALUATION OF PHOSPHORUS REQUIREMENT BY THE SORPTION ISOTHERM TECHNIQUE IN SOILS AMENDED WITH ORGANIC MATERIALS

SUMMARY Phosphorus requirement was evaluated by the sorption isotherm technique by means of laboratory and greenhouse experiments which were carried out at the Department of Soils and Environmental Sciences of the University of California, Riverside (CA), USA, from January to November of 1985. Two soils with different sorption capacities received increasing amounts of barley straw, cowpea plant tops, dairy manure and sewage sludge. The addition of the organic materials studied decreased P sorption capacity of the soils, except when the [...]