Spatial Variability of Soil Properties in Archeological Dark Earth Sites under Cacao Cultivation

• Published in: Revista Brasileira de Ciência do Solo Vol. 40
• Main Authors: Silva, Douglas Marcelo Pinheiro da, Campos, Milton César Costa, Franciscon, Uilson, Alho, Leandro Coutinho, Santos, Luis Antônio Coutrim dos, Paula Neto, Pérsio de, Bergamin, Anderson Cristian, Souza, Zigomar Menezes de
• Format: Journal Article
• Language: English
• Published: Sociedade Brasileira de Ciência do Solo 2016
• Subjects: Amazon soils; anthropogenic soils; Indian Dark Earth; management systems
• ISSN: 0100-0683; 1806-9657; 0100-0683
• DOI: 10.1590/18069657rbcs20140816

ABSTRACT Soils with an A horizon formed by human activity, an anthropogenic A horizon, are found in the Amazon Region. Few studies have examined the spatial distribution of the properties of these soils. We mapped the spatial variability of some soil properties in an area of Archaeological Dark Earth (ADE) in the Brazilian Amazon. A sampling grid was defined over an area of 42 × 88 m under cacao cultivation in which sampling points were established at a spacing of 6 × 8 m, for a total of 88 points. Samples were collected from the 0.00-0.05, 0.05-0.10, 0.10-0.20, and 0.20-0.30 m depth layers. Soil texture, aggregate stability, and organic carbon (OC) analyses were performed on disturbed soil samples. Undisturbed samples were used to determine soil macroporosity (Macro), microporosity (Micro), total porosity (TP), and soil resistance to penetration (RP). The results were analyzed by descriptive statistic, Pearson correlation (p<0.01), and geostatistics. Soil bulk density, total pore volume, and geometric mean diameter are dependent on the total amount of OC in the ADE area. Increased soil bulk density and RP are proportional to a decrease in OC content and lower Micro and TP. Moreover, soil resistance to penetration is influenced by soil water and clay content with depth.