Forest species cultivation like eucalyptus pasture soils can lead to changes in the decomposition process of plant residues and in the soil organic matter formation (SOM), mainly by altering the different organic compounds contribution and modifying the activity and microbial diversity. Thus, this study was to evaluate the changes caused by the eucalyptus cultivation in organic compounds such as phenols from lignin, carbohydrates, and amino sugars to identify the decomposition stage and the compounds contribution from microbial origin for the SOM in the North Coast's soils from Espírito Santo, Brazil, in comparison with those ones of pasture. The results indicated a lower carbohydrates' contribution and lignin content in the Eucalyptus leaf litter similar to those ones of pasture. The phenols from lignin, which are characterized by the compounds presence from cinnamyl group (ferulic and p-coumaric acids) in higher levels, reflected an increased of these compounds accumulation and of the total carbohydrates in the pasture soil, although the total lignin content, TOC (total organic carbono), TN (total nitrogen), and amino sugars were similar among crops. In cultivated soils with eucalyptus, a higher components contribution from plant origin (lower H/P relation) for the SOM was got than those from microbial origin, compared with the soils under pasture. Certain amino sugars content such as glucosamine in the soils indicated that fungi are more abundant than bacteria and actinomycetes, especially in the pasture soil.
Soil organic matter; Microorganisms; Glucosamine
