Soils Developed on Geomorphic Surfaces in the Mountain Region of the State of Rio de Janeiro

Abstract

The evaluation of soils in representative landscapes constitutes an opportunity to evaluate spatial distribution, discuss formation processes, and apply this knowledge to land use and management. In this sense, from the perspective of an environmentally diversified region, the aim of the present study is to evaluate the occurrence and understand the formation of soils in different geomorphic surfaces of a landscape from a mountain region in the state of Rio de Janeiro. The study was developed in the Pito Aceso microbasin in the municipality of Bom Jardim, composed of narrow valleys and a rugged mountain domain, with elevation between 640 and 1,270 m. In a representative landscape, the geomorphic surfaces were obtained from the slope segments and flow lines. On the geomorphic surfaces, soil profiles were described by their morphological properties, collected, and analyzed to describe the chemical and physical properties of each horizon. Geomorphological aspects and possible variations of the parent material directly affected pedogenesis and led to distinct soil classes in the landscape. Variation in the geomorphic surfaces directs the processes for soil formation under current conditions, as well as the preservation of polygenetic soils. Soils of lower development and with greater participation of the exchangeable cations were identified at the summit (talus deposit) (Neossolo Litólico and Cambissolo Húmico) and toeslope (colluvial-alluvial) (Neossolo Flúvico), whereas more developed soils with lower nutrient content occur in the concave (Argissolos Vermelho and Amarelo) and convex (Latossolo Amarelo) backslope, except for the Argissolo Vermelho-Amarelo in the shoulder, which had high exchangeable cations contents.

Resistance of Soil Organic Matter in “Humic A Horizons” of the Mountainous Region in the State of Rio De Janeiro

“…The local relief is characterized by rugged topography including slopes of various altitudes and narrow valleys; the elevation varies between 640 and 1,270 m above sea level. More information on local relief, geology, climate, vegetation, and land uses (P05, Eucalyptus plantation; P09, olericulture; P12, pasture; P13, coffee cultivation; and P35, passion fruit cultivation) can be found in Chagas et al (2012) and Fontana et al (2017).…”

“…According to the Brazilian Soil Classification System, the humic A horizon is a thick, dark-colored layer with high organic carbon content and low base saturation (Santos et al, 2018). These unique characteristics are a reflection of soil formation, landscape evolution and cultural practices (Volkoff et al, 1984;Benites, 2002;Dias et al, 2003;Dalmolin et al, 2006;Silva et al, 2007;Calegari, 2008;Fontana et al, 2010Fontana et al, , 2017.…”

“…It was formed in past climates under conditions that favored high accumulation of organic matter, mainly graminoids in dry climates between the early-Pleistocene and mid-Holocene (Calegari, 2008). According to Buol & Eswaran (2000), Calegari (2008), and Fontana et al (2017), its occurrence is a result of the formation of stable organo-mineral complexes that protect Soil Organic Matter (SOM) from decomposition and against water erosion caused by its convex relief.…”

A multi‐proxy study of Umbric Ferralsols genesis in a high‐mountain environment in Rio de Janeiro state

“…In the state of Rio de Janeiro, southeastern Brazil, Umbric Ferralsols can be observed in Serra dos Órgãos, which corresponds to a segment of the Serra do Mar and has an extremely fragile ecosystem due to its geoenvironmental aspects (Calderano Filho et al, 2019; Fontana et al, 2017; Nehren et al, 2016). Thus, a greater understanding of pedogenesis, associated with the context of landscape evolution and the factors associated with organic matter accumulation, can contribute to the maintenance of these soils and preservation of these environments (Araujo et al, 2017; Calderano Filho et al, 2019).…”

The Use of a Sequential Extraction Technique to Characterize Soil Trace Evidence Recovered from a Spade in a Murder Case in Brazil*

“…The use of soils in forensic investigations can be a valuable source of information due to its variable nature and the ability to ascertain the likely origin of soil traces adherent to a wide range of objects and people, including shoes, tires, clothes, and hair (5)(6)(7)(8)(9). Soil variability derives from pedological processes such as the underlying geological parent material, position in the landscape, predominant local climate, human action, vegetation, living organisms in the soil, and time (10,11). Each of these factors in turn defines the intensity of weathering, which will result in the formation of specific soil types.…”