In the geomorphological unit of the Coastal Tablelands of Brazil there is a predominance of cohesive soil horizons and some with the presence of cemented horizons, commonly of the fragipan type. These horizons interfere with water dynamics, root growth, and, consequently, mineral nutrition of plants. The objective of this study was to use selective dissolution to evaluate the participation of forms of Fe, Si, or Al, or their combination, in the cohesion or cementation or both of fragipans and cohesive […]

The occurrence of cohesive soils in Brazil is predominantly related to sandy-clay sediments of the Barreiras Formation, which are geologically related to the sedimentary deposits of the Tertiary period (from Paleocene to Pliocene), which constitute the geomorphological unit of the Coastal Plains. The objective of this study was to identify the occurrence of cohesive soils in the eastern region of the state of Maranhão, Brazil, and assess their relationship to position in the landscape. The area under study is in […]

The cohesive character is an attribute of subsurface soil horizons with hard to extremely hard consistency when dry, and friable or firm when wetted. Despite the agricultural importance, the formation of these horizons is not yet completely understood. The objective of this study was to characterize and assess the possible mechanisms involved in the formation of cohesive horizons in soils of the Coastal Tablelands of Northeast Brazil, in order to understand their pedogenesis and to identify physical and chemical parameters […]

There have been several papers in the literature studying the genesis and consequences of particles cohesion in Argisols (Ultisols) and Latosols (Oxisols) from the Brazilian Inner and Coastal Plains. Just a few, however, provide insights into the clay fraction mineralogy, specially, the iron oxides complete characterization. The objective of this study was to investigate the chemical and crystallographic characteristics of iron oxides in red and yellow soils derived from the sediments of the Barreiras Formation or Pre-Cambrian rocks in the […]

The cohesive soils of Brazilian coastal plain have subsurface horizon with a peculiar characteristic – when wet the consistency is friablet, but of hard, very hard or extremely hard consistency when dry. The objective of this study was to evaluate the mechanical characteristics of cohesive and non-cohesive horizons of a Yellow Latosol of coastal tableland based on shear parameters related with soil physical and chemical properties and moisture. The results showed that soil cohesion and shear strength increased substantially with […]

The shear tension and soil cohesion are important soil physical properties. They are affected by management systems and the content of Fe, Si and Al oxides in the soil. The effects of different sugarcane management systems on the shear tension, angle of internal friction, soil cohesion, and the contents of Fe, Si and Al oxides in a Cohesive Yellow Argisol were studied in four areas of the Triunfo mill in Alagoas State, Brazil. The treatments consisted of an area cultivated […]

Inadequate crop practices are among the main causes for reduced productivity of cashew crops in the Northeast of Brazil. Periodical elimination of vegetation and the use of heavy machines and implements influence soil temperatures and density, possibly affecting plant growthand development. This is an aggravating fact, considering the sandy soils and climate conditions of the region. This study had the objective to investigate the development of cashew nut plants (early-dwarf cultivar) at different levels of soil temperature and density, to […]