ORGANIC MATTER EVALUATION OF A BRAZILIAN OXISOL BY SPECTROSCOPIC TECHNIQUES

摘要

There is still the necessity of understanding qualitative and quantitative changes that take place in soil organic matter(OM)and spectroscopic techniques have been largely applied in conducting related studies.The use of spectroscopic techniques,such as EPR,NMR,and others,allows possible insights into the chemical composition of humic substances(HS).They also permit the determination of parameters related to the humification process of OM in soils,such as the degree of aromaticity,revealed by solid state ~(13)C NMR(Stevenson,1994),and the semiquinone-type free radical concentration,determined by EPR(Martin-Neto et al.,1991).