Degradation and Restoration of Anthrosols in the Amazonia Under Contrasting Agricultural Practices: Evidence From the Assessment of Soil Physical Quality and Carbon and Nitrogen Stocks

ABSTRACT This study was conducted to assess the impact of different agricultural practices on the physical quality and the carbon and nitrogen stocks of anthropogenic soils used by smallholder farmers in Central Amazonia, Brazil. Undisturbed and disturbed soil samples were collected at three depths (0–0.10 m, 0.10–0.20 m, and 0.20–0.30 m), with five replicates, for determination of particle‐size distribution, aggregate and structural stability indexes, soil bulk density, and carbon (C) and nitrogen (N) contents, from which the corresponding C and N stocks were calculated. To quantify C and N stocks, soil mass correction across layers was applied using the native forest site as the reference. The results indicated that management practices involving mechanization and long‐term reduction in soil cover altered the physical quality of Amazonian Anthrosols, reducing their C and N stocks compared with soils under native vegetation. Attributes related to structural stability proved to be sensitive indicators for assessing physico‐chemical quality in both Black Earth and Brown Soil. As with soils of natural origin, the preservation of native forests, combined with the effective implementation of sustainable agricultural practices in cultivated areas, is essential for maintaining the quality of anthropogenic soils in Central Amazonia and to enhance carbon sequestration. The findings reinforce the need to develop tailored agricultural practices that mitigate negative impacts on these unique archaeologically relevant soils.