Volume 25, Number 2, 2001

Little is known about the effect of mafic parent materials on soil genesis in the humid “Zona da Mata”, Minas Gerais, although there are many detailed studies on soils developed from felsic to mesocratic gneiss, notably Latosols and terrace Podzolic soils. To fill this gap, soils in two topolitosequences, comprising A and B or A and C horizons, were sampled and studied. In the first topolitosequence, at Serra de Guiricema, a Red-Yellow Latosol on the top, a Argilluvic Chernosol, a […]

The formation of soils with argillic horizons was investigated to identify the pedological processes involved in the formation of lamellae and the abrupt textural gradient as well as their implication on the soil physical, chemical and mineralogical attributes. This study was carried out on a sandstone-derived soil toposequence, with profile (P1) occupying the higher part of the landscape (summit), profile (P2) on the backslope, and profile (P3) on the footslope. Soil chemical, mineralogical, micromorphological and particle size distribution analyses were […]

On the landscape of the Eastern Plateau, north of the State of São Paulo, Brazil, there are ferricretes in different elevations. Although these features are relatively frequent over the cretaceous sandstone (Adamantina Formation, Bauru Group), little investigation has been carried out on their genesis. A morphological study at different levels of observation was conducted in order to elucidate the genesis of ferricretes (plinthite and petroplinthite), occurring at the toeslope of a landscape where soils with argillic horizon predominate, at the […]

An experiment, covering 12 cultivations, was carried out at Embrapa Rice & Beans Research Center, Santo Antônio de Goiás, Goiás, Brazil, in an Oxisol under center pivot, for six consecutive years. The effects of four soil tillage systems and six crop rotations on pH in water, exchangeable Al and Ca + Mg, organic matter, extractable P, and exchangeable K were evaluated, using a completely randomized design, in a splitplot arrangement, with three replications. The tillage treatments were: moldboard plough/harrow disc, moldboard plough, […]

This study, covering 12 cultivations, was carried out at Embrapa Rice & Beans Research Center, Santo Antônio de Goiás, Goiás, Brazil, in an Oxisol, under center pivot, for six consecutive years. The effects of four soil tillage systems and six crop rotations on bulk density and soil porosity were evaluated. The experiment was conducted in a completely randomized design, using a splitplot arrangement, with three replications. The tillage treatments were: moldboard plough/harrow disc, moldboard plough, harrow disc, and no-tillage. Tillage […]

The estimative of the maximum surface runoff volume is fundamental to design several types of hydraulic structures as, for example, level terracing systems. The incorrect estimative of the surface runoff volume causes a wrong design of these systems and when overestimated present high installation cost. Considering these aspects, the present study aimed to compare the values of the surface flow maximum volume obtained by the empiric method of the curve number and developed by the USA Soil Conservation Service, with […]

Water erosion is one of the main processes associated to environmental degradation. The soil detachment and transport depends of the raindrop impact and surface runoff. As the agricultural production losses result from water erosion, the correct design of soil conservation systems is necessary to avoid high costs of installation and maintenance. Pruski and collaborators developed a model to estimate the maximum surface runoff depth under typical agricultural conditions. The objective of this study was to evaluate the model developed by […]

Soil tillage and consolidation modify soil resistance to rill erosion. Thus, an experiment was carried out on a Hapludulf, under field conditions in 1997/98, to study rill erosion under different tillage methods and soil consolidation, to evaluate the sediment size and to determine rill erodibility (Kr) and critical shear stress (τc). The experiment was completely randomized with six replications, using the following treatments: recent conventional tillage (RCT), two-month consolidated conventional tillage (CCT), no-tillage with mulch (NTM) with 94% surface coverage […]

A tilled soil has increased susceptibility to raindrop impact and sediment transport by laminar surface flow and splash, but after tillage the soil reconsolidates, increasing again its resistance. Thus, an experiment was conducted on a Hapludalf with Sandy loam soil surface, under no-tillage for eight years, to evaluate interrill erosion under different tillage methods. The experiment was totally randomized with six replicates. The treatments were recent conventional tillage (RCT), two-month consolidated conventional tillage (CCT), no-tillage with mulch (NTM) with 94% […]

The study of the effects of soil tillage systems on some physical and chemical properties of a Typic Paleudal and on cassava yield (Manihot esculenta, Crantz) was carried out in the northwest of the state of Paraná, Brazil in 1994/95 and 1996/97. Three soil tillage systems were used: (a) no-tillage; (b) minimum tillage (field cultivator and disc harrowing); and, (c) conventional tillage (mouldplowing and disc harrowing). A randomized complete block experimental design with six replications was used. Higher macroporosity values in the 0.10 m […]