Soil Organic Carbon Fractions and Fertility Across Degraded, Forest, and Restoration Areas in Desertification Hotspots of the Brazilian Semiarid Region
Josivânia Araújo Duarte, José Félix de Brito Neto, Evandro Franklin de Mesquita, Vicente Victor Lima de Andrade, Cristiano dos Santos Sousa, Antônio Carlos Andrade da Silva, Franklin Sales de Araújo, Rodrigo Santana Macedo, Walter Esfrain Pereira, Emanuel da Costa Cavalcante, Ademir Sérgio Ferreira Araujo, Erika Valente de Medeiros, Arthur Prudêncio de Araújo Pereira, Rennan Fernandes PereiraSoil organic carbon fractions and fertility attributes may differ among land-use conditions in the Brazilian semiarid region due to environmental heterogeneity, soil properties, and land-use history. This study compared soil attributes in degraded, forest, and restoration areas across four desertification hotspots located in Ceará (CE), Paraíba (PB), Pernambuco (PE), and Piauí (PI), Brazil. Surface soil samples (0–10 cm) were collected from four independent plots per land-use condition within each hotspot and analyzed for particle-size distribution, pH, total organic carbon (TOC), humic fractions, available phosphorus, exchangeable cations, and potential cation exchange capacity (CEC). The magnitude and direction of differences among land-use conditions varied across the investigated hotspots. Forest areas exhibited 12% and 57% higher TOC contents than degraded areas in PB and PI, respectively. In PB, humic acid carbon contents were approximately 85–95% higher in forest and restoration areas than in the degraded area, while humin carbon content in the restoration area was 136% higher than in the degraded area. Available phosphorus was markedly higher in restoration areas in PB and PI. In PI, the restoration area exhibited high Ca2+ and Mg2+ contents and potential CEC, whereas soil pH ranged from approximately 5.1 in the forest area to 8.0 in the degraded area. These findings reveal substantial spatial variation in soil carbon fractions and fertility attributes among land-use categories, potentially associated with differences in soil texture, pedogenic characteristics, and previous land management. The results highlight the importance of considering local edaphic conditions when assessing soil quality across contrasting land-use categories in semiarid environments.