Detailed soil survey of an experimental watershed representative of the Brazilian Coastal Plains and its practical application

Abstract

This paper presents a detailed soil survey of an experimental watershed with representative pedoclimatic characteristics of the Coastal Plains in Espírito Santo State and its practical applications. For the pedological survey, 35 observation sites and three soil profiles were sampled and described, which were morphologically characterized and subjected to physical (particle size) and chemical analyses (routine and sulfuric acid digestion). The soil map was made using the geographic information system ArcGIS 9.3. This GIS software was also used to generate the digital elevation model (DEM) for identifying the slope classes. SAGA software was used to calculate the topographic wetness index (WI) which aided in a more accurate separation of Haplic Organosol from other soils. The predominant soil class in the watershed was the dystrophic/dystrocohesive Yellow Argisol (97%), containing morphological, chemical and physical characteristics representative of the most expressive Coastal Plains soils. Geoprocessing tools and techniques aided to make the watershed soil map.Index terms: Soil map, geoprocessing, GIS. RESUMONeste trabalho, apresenta-se o levantamento detalhado de uma microbacia hidrográfica experimental representativa das características pedoclimáticas dos Tabuleiros Costeiros brasileiros e sua aplicação prática. Para o levantamento pedológico, foram descritos morfologicamente e amostradas 35 microtrincheiras e três perfis modais, cujas amostras foram submetidas a análises físicas (textura) e químicas (fertilidade e ataque sulfúrico). A confecção do mapa de solos foi realizada, utilizando-se o sistema de informação geográfica ArcGIS 9.3, no qual foi gerado o modelo digital de elevação (DEM) para a separação das fases de relevo. Utilizou-se também o programa SAGA GIS, para a geração do índice topográfico de umidade (WI) que auxiliou na separação mais precisa do Organossolo Háplico dos demais solos. A classe de solo predominante na microbacia foi o Argissolo Amarelo distrófico/ distrocoeso (97%), com características morfológicas, químicas e físicas representativas dos solos mais expressivos dos Tabuleiros Costeiros. Ferramentas e técnicas de geoprocessamento auxiliaram na confecção do mapa de solos da microbacia.Termos para indexação: Mapa de solos, geoprocessamento, SIG.

Modeling and prediction of sulfuric acid digestion analyses data from PXRF spectrometry in tropical soils

“…The range of SAD values result from different factors of soil formation (Tables 1, 2, and 3), similar to values found for other soils from other regions of Brazil (Curi and Franzmeier, 1987;Vasconcelos et al, 2013;Santos et al, 2014;Carvalho Filho et al, 2015). Soils developed from itabirite, basalt, gabbro, and tuffite presented the highest Fe O 3 and TiO 2 contents and the lowest SiO 2 contents.…”

Proximal Sensing and Digital Terrain Models Applied to Digital Soil Mapping and Modeling of Brazilian Latosols (Oxisols)

“…Data in Table 3 show that Fe was the unique variable used for mapping all four soil classes, while the other three variables were employed for at least one soil class, such as SWI, although in all cases, a soil class required more than one variable to be mapped. 1 Similarity to the typical condition. 2 The curve type for LVg is S-shaped, while for other soils, it is bell-shaped.…”

“…The small scale of most soil maps in Brazil is not suitable for land use planning and for defining soil and water conservation practices, which need to be done in more detail, i.e., at the level of watersheds [1], as established by the current legislation in Brazil [2]. The lack of financial support along with the large area of the country and the scarcity of roads are some of the main issues restricting the creation of more detailed soil maps, since they require intensive field work for sampling and classifying soils.…”

Soil compaction caused by harvesting, skidding and wood processing in eucalyptus forests on coarse‐textured tropical soils

“…The Hapludults in the Bt horizon were the most resistant to compaction, indicated by their position in the biplot associated with lower θ and higher σ p despite the lower ρ b , resulting in lower DC and a smaller increase in ρ b (soil physical attribute values are in Table ). The Bt horizon in these Ultisols usually constitutes a layer of increased mechanical strength, sometimes becoming very hard when dry (Santos et al., ). Although our results indicated a lower risk of subsoil compaction in these soils, subsoiling is often needed to alleviate this naturally more resistant layer.…”

“…An additional practical implication is that although the more coarse‐textured surface horizons or layers may endure less severe compaction because of their dryer condition, it is important to consider the soil moisture throughout the solum, since the deeper layers may be wetter and thus more prone to compaction. This is very important in these soils because they typically have a denser and naturally compact layer in the upper B horizon (Santos et al., ). Additional compaction in this situation would be likely to severely hamper root growth, which for Eucalyptus may expand down to 8–10 m 2 years after planting in coarse‐textured soils (Pinheiro et al., ).…”