Estudo da humificação da matéria orgânica de um cambissolo em diferentes sistemas de manejo por meio de técnicas espectroscópicas

Abstract

Stocks and stability of soil organic matter (SOM), even accounting approximately 5% of soil total, are indicators of quality and sustainability of the management system to which the soil is submitted, it has influence on nutrient availability for plants, assists in erosion retention, increases aggregates stability and assists in carbon sequestration. As labile SOM becomes stable through the humification process, affected by climate, soil type and management systems, the molecular structures gain complexity resulting in the formation of groups such as fluorescent aromatic rings and quinines, which can be evaluated by spectroscopy techniques. The purpose of this research was to use spectroscopic techniques to measure the humification of organic matter in a Cambisol, which comes from Irati – PR, submitted to two management systems: conventional tillage and no-tillage (six years and nine years). The forest was used as comparison. Analysis were performed using laser induced fluorescence (LIF) in whole soil (no chemical or physical treatment), and fractions obtained by physical fractionation by granulometry: (clay), (silt) e (fine sand) e (sand). The samples were also analyzed for fluorescence of humic acids, obtained by chemical fractionation of soil and absorption spectroscopy, UV-Visible ( ratio). The results of these tests show no difference in the degree of humification of SOM between management systems.