Effect of hydrophysical properties on pipe formation in tropical soils

Autor(es)

Bovi, Renata Cristina ; Pessoa, Thais Nascimento ; Boschi, Raquel Stucchi ; de Pierri Castilho, Selene Cristina ; Libardi, Paulo Leonel ; Cooper, Miguel

• Tipo de documento: Artigo Científico
• Fonte: Science of The Total Environment; v. 827, p. 14-pg., 2022-06-25.

Resumo

Piping is an erosive process in which subsurface soil particles are removed, causing the formation of underground tunnels. A variety of physical and chemical factors control pipe formation. This study focused on hydrophysical soil properties to propose a mechanism to explain the piping process in soils in a tropical climate in Brazil. We observed two levels of pipes in the field: shallow pipes that form at the transition between E/B horizons (similar to 0.30-0.45 m) and deep pipes that form between different Bt horizons (similar to 1.50 m). We collected disturbed soil samples to determine the soil particle distribution and organic matter content, and undisturbed soil samples were collected to determine the hydrophysical attributes and for soil micromorphometric analysis. We found that the study area was prone to soil collapse and that physical properties controlled the process. The results showed a textural and structural gradient between the E and Bt horizons, where the Bt horizons presented a higher clay content and a well-developed structure (strong sub-angular blocks) compared to the essentially sandy E horizons (single grain). This gradient changed the soil porosity from macroporosity in the E horizon to microporosity in the Bt horizon, particularly represented by the decrease in complex pores. For deeper pipes, soil attribute gradients were found between different Bt horizons. A modification in the structure grade from moderate to weakly moderate, soil water retention curves with different slopes and shapes, and an increase in porosity correlating with soil depth, reflect an increase in larger complex pores. These changes in structure, texture, porosity, and pore type reflect the soil's hydraulic conductivity in the transition of different horizons, which can promote the accumulation and temporary stagnation of water at the top of the Bt horizons, and trigger the piping process when the lateral water flow reaches the critical flow velocity. (AU)

• Processo FAPESP: 20/11502-0 - Relação solo-planta no Estuário do Rio Doce: uma abordagem dendroquímica e da dinâmica de elementos potencialmente tóxicos em solo afetado por rejeitos de minérios
• Beneficiário: Renata Cristina Bovi
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado