Frações do carbono orgânico do solo em área de mineração de bauxita com diferentes estádios de restauração florestal em Juruti

Abstract

The objective of the study was to quantify the total organic carbon contents andtheirrespective chemical fractions. The study was carried out in the municipalityof Juruti (PA),located in the Lower Amazon Mesoregion. Three areas with different forest restorationtimesand a reference area were selected: A1: reforested area in 2018; A2: area reforestedin2015;A3: area reforested in 2012; and A4: Forest area. In each sampling area, sampleswerecollected to evaluate the chemical properties of the soils. The deformedsampleswerecollected at depths of 0-0.05, 0.05-0.10, 0.10-0.20 m by opening four mini trenchesineacharea. In each mini trench, 3 simple samples were taken by depth. The samples wereair-driedand crushed, and passed through 2mm sieves to obtain air-dried fine soil. Inthis material, thelevels of total organic carbon (TOC), particulate organic carbon (POC) andorganiccarbonassociated to (OCam) minerals were quantified. The carbon contents of the fulvicacid(CFAF), humic acid (C-FAH) and humins (C-HUM) fractions were also quantified. At adepthof 0-0.05 m, in area A4 (forest) the highest contents of TOC, OCam, C-FAHandC-HUMwere quantified; at a depth of 0.10-0.20 m, in area A1 (most recent restoration), thehighestcontents of TOC, POC, OCam, C-FAF, C-FAH and C-HUMwere observed. It is concludedthat the forest restoration process in the mined areas, using the nucleation method, wasabletomaintain or increase the total organic carbon contents and their respective physical andchemical organic fractions.