Mineralogia e disponibilidade de fósforo em solos de terra firme da Amazônia Central

Abstract

The interaction of the element phosphorus (P) with soil is one of the most studied subjects in soil science. This is due to its complex dynamics, especially in moist tropic soils with a high degree of development that lead to the low efficiency of phosphate fertilization. However, these characteristics can vary according to the peculiarities of each region, and, consequently, may require a management differentiated of P fertilization. Objective 1: To characterize the mineralogy of clay fraction of the arable layer of dryland of Central Amazonia, trying to establish its relations with the dynamics of P in these soils. Objective 2: To evaluate the effect of the interaction between the contact time of a source of soluble phosphorus with 10 dry land soils of central Amazonia on the availability of phosphorus. The predominant minerals in the studied soils are kaolinite, goethite and hematite, but the mineral content, crystallography, specific surface area, degree of isomorphic substitution, and levels of pedogenetic iron were quite different among soils. It is suggested that they respond differently to phosphate fertilization. P availability was higher at lower contact times of soil with phosphate, while P uptake and dry matter yield of sorghum plants were higher at the contact times.