Método para determinação de Fósforo microbiano inorgânico em serrapilheira da Amazônia

Abstract

The study of leaf litter and its decomposition is fundamental to understanding nutrient dynamics in forest ecosystems, especially in tropical regions such as the Amazon, where phosphorus availability is often limited and heavily dependent on microbial biomass. However, microbial phosphorus (P-mic) determination in leaf litter is still estimated using methods implemented in soils and adapted for phosphorus quantification in leaf litter. These adapted methods have not been validated for this studied matrix to achieve analytical precision. Classical techniques using chloroform fumigation are more commonly used and are complex and difficult to implement in regional laboratories. This work proposes and evaluates an analytical methodology for P-mic determination, based on extraction with Mehlich I solution, with disruption of microbial membranes, using microwaves, and quantification by spectrophotometer, via the phosphomolybdate blue reaction. The results indicate good linearity (R² = 0.999) using standard addition recovery and good reproducibility in litter samples ground to 1.0 mm. The proposed method stands out for its low cost, shorter analysis time, elimination of chloroform, low standard deviation (0.50), lower coefficient of variation (3.2%), and greater precision. The proposed method offers a promising tool for studies on nutrient cycling and sustainable management in Amazonian ecosystems.