Abstract
Human activities often alter soils found in urban areas. These alterations affect their environmental functions and potential for use. However, soils from urban areas in Brazil have not been surveyed and identified, which can pose a technical problem for the development of the city. Considering the importance of urban environments and their soils, this study aimed to evaluate the environmental and morphological characteristics and the physical properties of urban soils in Santa Maria, Rio Grande do Sul, Brazil. The purpose was then to organize a protocol for describing urban soils and to identify diagnostic qualifiers to subsidize establishment of an order that allows proper classification of these soils in the Brazilian Soil Classification System. The protocol containing general and environmental notes and morphological notes and qualifiers was organized based on the experience of this study and the relevant literature. The environmental, morphological, and physical analyses carried out supported interpretation of the urban soils of Santa Maria, their classification in the World Reference Base for Soil Resources system, and identification of diagnostic qualifiers proposed for the Brazilian Soil Classification System. The protocol tested in this study was adequate for data collection in the field. Soils had high variation in layer thickness, particle size composition, color, bulk density, saturated hydraulic conductivity, penetration resistance, stoniness, and the presence of artifacts. Considering the establishment of a Brazilian taxonomy for urban soils, the field data led to the proposal for new qualifiers, such as Saprolitic (residual saprolite material), Impervic (sealed/impermeable layer), Multigranic (layers with contrasting textures), Stonic (layers with stoniness), and Saprorockic (layers constituted of transported saprolite), which can be used as diagnostic attributes in the Brazilian Soil Classification System and even contribute to improvement of the order of Technosols in the World Reference Base For Soil Resources system.
Highlights
Human influence on the environment can be identified in several places of human occupation and soil is one of the main sources with a record of anthropogenic activities, especially those under urban environments, whose attributes have been described in recent years by several authors, such as Jim (1998), Morel and De Kimpe (1998), Pedron et al (2004), Greinert (2015), Gorbov (2016), and Zalasiewicz (2017)
Considering the establishment of a Brazilian taxonomy for urban soils, the field data led to the proposal for new qualifiers, such as Saprolitic, Impervic, Multigranic, Stonic, and Saprorockic, which can be used as diagnostic attributes in the Brazilian Soil Classification System and even contribute to improvement of the order of Technosols in the World Reference Base For Soil Resources system
In the selection of the soil profile areas in the urban soil survey of the city and the field trips made during the study, we could not find altered soils with the following land uses: soil deposition area, urban agriculture area, and permanent preservation area, because most of those areas in Santa Maria still maintain a natural soil cover
Summary
Human influence on the environment can be identified in several places of human occupation and soil is one of the main sources with a record of anthropogenic activities, especially those under urban environments, whose attributes have been described in recent years by several authors, such as Jim (1998), Morel and De Kimpe (1998), Pedron et al (2004), Greinert (2015), Gorbov (2016), and Zalasiewicz (2017). The methods of soil description and collection are consolidated for natural environments (Santos et al, 2015), whose soil characterization is based on profile description (sequence and depth of horizons, textural class, color, structure, special features, etc.), sample collection, laboratory analysis (chemical and physical analysis), and data interpretation. When it comes to urban soils significantly altered by human activities, there is a lack of information (or field protocol) that guides technicians in this work (Pedron et al, 2007), as well as a lack of a Brazilian taxonomic classification to characterize these specific environments. The few studies on this subject in Brazil have been carried out with adaptations of the procedures used for natural soils, without standardization that would allow qualification of the data and later comparison among the studies
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