Urban soils in Brazil: A review

This study analyzes the scientific production about soils within cities in Brazil, the most populous country of Latin America, to highlight significant patterns and contributions and point out gaps and future challenges. A more robust literature about urban soils in Brazil started in the 90 ' s decade and has intensified since 2015. Papers are mostly published in Portuguese, majority performed in cities with more than 500,000 inhabitants, many of them located in the Southern and Southeastern regions, and mainly focused on soil characterization, classification, mapping and/or contamination. Important methodological propositions (related to classification and land potential) and morphological, physical and chemical results are published. Urban soils formed from landfills are the most common, but soils developed from irregular zones of waste disposals are also frequent, showing the deficiency of proper waste management in developing countries. Properties such as pH, base saturation, soil organic matter and P amounts tend to be higher in soils marked by the addition of earthy materials and solid waste than in soils developed from the process of cutting, which commonly exposes the acid and deep saprolite of the tropical and subtropical zones. Although the attention on the Brazilian urban soils has grown in the last years, more studies, with a higher variety of morphological and analytical data, still have to be performed to obtain more representative results. Systematization of concepts, terminologies, and methodologies is also necessary, allowing a more complete understanding of the soils. In addition, the incorporation of a classification key of Anthropogenic soils, including urban soils, in the Brazilian official classification system seems urgent. Finally, it is relevant to foment international publications about the Brazilian urban soils, allowing a wider comparison between the produced data and the results obtained worldwide.