RESUMO O objetivo deste estudo foi estimar o potencial de perda de solo por meio da equação universal de perda de solo e identificar os fatores que controlam o processo erosivo em uma bacia hidrográfica de encosta. O fator erosividade da chuva (R) foi calculado por meio de dados normais de precipitação, obtendo-se, assim, índices mensais de erosão. O fator erodibilidade do solo (K) foi obtido a partir de uma amostragem de solo realizada por meio de uma malha de 340 pontos, na qual os valores foram interpolados pelo método da krigagem ordinária. O fator topográfico (LS) foi gerado a partir do Modelo Digital de Elevação (MDE), já os fatores uso e manejo e práticas conservacionistas (CP) foram obtidos por meio de observações de campo e valores tabelados. As maiores taxas de perdas abrangem 27% da área e se concentram em locais de maiores declividades nos quais predominam solos rasos, como Neossolos Litólicos e Neossolos Regolíticos. O fator LS determinou a magnitude do processo erosivo e o fator CP apresentou a maior relação com o controle das perdas de solo. Os resultados encontrados mostram a importância do fator cobertura do solo, em que medidas de manutenção da vegetação e práticas conservacionistas devem ser adotadas e consideradas pelos gestores ambientais em regiões de encosta com predomínio de solos rasos associados a relevo declivoso.

No abstract

The largest Brazilian coal mine, called Candiota mine, is located in South Brazil, with an estimated reserve about 1.2 billion tons. Since late 2003, an experiment located at a reclaimed site in a coal mining area was conducted, in which a research group from the Federal University of Pelotas has been conducting a long-term experiment on soil quality with different plants species, such as Hemarthria altissima, Paspalum notatum cv. Pensacola, Cynodon dactylon cv. Tifton, and Urochloa brizantha. After 8.6 years of revegetation, soil samples at 0.20 depth were collected in minesoil and natural soil to determine physical attributes, and the organic carbon content. After 10.9 years of revegetation, soil samples at 0.10 m depth were collected to determine the biological attributes. According to the research results, it can be seen that the recovery of minesoil was more effective after 8.6 years of revegetation only in the physical condition up to 0.10 m depth. However, all soil physical attributes and organic matter content are still below the levels observed in the natural soil. The biological attributes after 10.9 years of revegetation have not yet been sufficient to restore a mites and springtails population close to the natural soil.

The main problems in the constructed soils are the generation of acid mine drainage promoted by the presence of coal debris in the overburden layer and the compaction of the topsoil promoted by the machine traffic when the material used in the overburden cover is more clayey. This book chapter aimed to show an overview of the impact of more than a decade of revegetation with different perennial grasses on the chemical, physical, and biological quality of constructed soil after coal mining. The study was carried out in a coal mining area, located in southern Brazil. The soil was constructed in early 2003 and the perennial grasses, Hemarthria altissima; Paspalum notatum cv. Pensacola; Cynodon dactylon cv Tifton; and Urochloa brizantha; were implanted in November/December 2003. In 11.5, 17.6 and 18 years of revegetation soil samples were collected and the chemical, physical, and biological attributes were determined. Our results show that liming is an important practice in the restoration of these strongly anthropized soils because this positively impacts the plants’ development, facilitating the roots system expansion. Biological attributes such as soil fauna and the microorganism’s population are the attributes that possibly takes longer to establish itself in these areas.

The conservation of native forests is fundamental to the preservation of hydric resources in the landscape. The use of animals in forest fragments has resulted in degradations in the soil, resulting in the grating of these. Thus, soil classes were studied and physical parameters of forest soils were evaluated in areas without and with cattle grazing in the “Arroio Pelotas” watershed, Pelotas, Rio Grande do Sul, extreme south of Brazil. The results were submitted to statistical analysis with the Kruskal–Wallis nonparametric test with a significance level of 5%. The means of the physical parameters of soil in the same toposequence and layers with and without the presence of livestock were compared. By analyzing soil physical attributes (density, macroporosity, and microporosity) it can be seen that the structural quality of the soil is affected by the access of animals inside the forest fragments, especially in the upper layer of the soil (0–5 cm deep). In forest fragments without access to animals, the physical structure of the soil presented the best conditions of macroporosity and, consequently, greater protection of nutrients, microorganisms, and water resources. Therefore, it is concluded that conservation by the isolation of protective forests in rural property planning benefits the quality of forest soils.