02385nab a2200325 i 4500 BR-BrBNA 20260512150044.0 260512b2020 bl.qr|pooa||| 00| 0 eng | BR-BrBNA eng P32 P33 Fontana, Ademir Pereira, Marcos Gervasio Balieiro, Fabiano de Carvalho Chagas, Cesar da Silva Donagemma, Guilherme Kangussu Oliveira, Lucienne Silva de Resistance of Soil Organic Matter in “Humic A Horizons” of the Mountainous Region in the State of Rio De Janeiro Publicação on-line; 36 ref.; 2 tables; 3 illus.; Summary (En) ABSTRACT Soils with high organic carbon content, such as those with “humic A horizon”, occur in different regions of Brazil. This study aimed to determine the quantitative and qualitative characteristics of organic matter regarding the humic A horizon under different land uses in Bom Jardim, in Rio de Janeiro State, Brazil. Samples from forest, pasture, Eucalyptus plantation, coffee cultivation, olericulture, and also passion fruit soils were sampled and analyzed. In October 2011, undisturbed samples from humic A horizons, were collected for soil density analysis. In addition, disturbed samples were collected for the determination of organic carbon (Corg) content, total carbon, humic substance fractions contents and natural abundance of 13Carbon (δ13C). Low Corg contents were observed in areas under olericulture, pasture and passion fruit cultivation. The fulvic acid fraction was higher than other fractions, regardless of land use. The small variability in δ13C indicated maintenance of original Corg and suggest high resistance of Soil Organic Matter in humic A horizons. Keywords: organic carbon, humic substances, isotopic composition. SOLO CARBONO COMPOSIÇÃO QUÍMICA ISÓTOPO MATÉRIA ORGÂNICA 2929 347956 Rio de Janeiro-RJ Instituto de Florestas - UFRRJ 1994 2025-0455 Floresta e Ambiente (Brazil) 1415-0980 / ISSN 2179-8087 0nline v. 27(1) p. 1-9; (2020) BR2026001224 https://www.scielo.br/j/floram/a/vSDStL9B9cWqvmH6yvFpGRM/?format=pdf&lang=en ANA 341777 341777