Allocation of phosphorus in a tropical savanna

The allocation of phosphorus (P) was studied in the different components of a Trachypogon savanna ecosystem, particularly in those related to biological productivity processes. The research was based on the sequential fractionation of soil P and on the determination of P content in different plant components. Soil is the principal reservoir of P (more than 99%), which is distributed mostly in forms of low availability. Microbial soil P represents about 6% of total P in this ecosystem, whereas cattle and vegetation accumulate about 1% P. The relatively high P content in microorganisms suggests the important role of this pool as a source of labile P and as a catalyzer of P transformations. Although available P forms are scarce, microorganisms and plants can satisfy their P requirements from the organic labile and moderately labile fractions, which account for 24% of total P in the soil.