Volume 35, Number 2, 2011

The aim of this study was a survey of the estimated costs of soil erosion, an issue of fundamental importance in view of the current worldwide discussions on sustainability. A list was drawn up of research papers on erosion (on-site and off-site effects) and their respective costs. The estimates indicate the amount of resources spent in the process of soil degradation, raising a general awareness of the need for soil conservation. On-site costs affect the production units directly, while off-site […]

The influence of parent material, varying from Plio-Pleistocene sediments and basic volcanics, and topographic position, to soil genesis, was studied in a topolitossequence typical of savanna at the Cauamé River catchment, Roraima. We aimed to describe the soil variability under savanna by means of chemical, physical and mineralogical attributes. Fourteen soil profiles were described and samples, allowing the identification of the following classes: Yellow Latosol, Red Latosol, Yellow and Red-Yellow Argisols, Plinthosols, Gleisols, Fluvic Neosols and Vertisols. The mineralogy was […]

With the development of soil classification to the fourth category level of the Brazilian Soil Classification System – SiBCS, it seeks the development and standardization of proposals for the classification of soils in 5 th and 6 th categorical levels (family and series). In this sense, this paper aims to available the viability of the humic fractions for the classification of diagnostic horizons in the 5th or 6th categorical levels (family and series) of SiBCS. For the development of the […]

The dynamics and properties of soil organic matter (SOM) in mineral soils have been studied for many years. However, under tropical conditions, few studies involve organic soils, the characterization of humic substances (HS), or their relationship with chemical properties related to the agricultural potential of Histosols. The objectives of this study were to characterize chemical properties of Histosols in different Brazilian regions; to quantify soil organic carbon and carbon in the SOM fractions; and to evaluate possible relationships between organic […]

Despite evidences that soil morphology and classification can be used to infer measurable soil properties and to correlate management results among different agricultural sites, there is still the need of data to support many of those inferences. The aim of this research was to validate the use of soil morphology and taxonomy to predict soil properties based on measurements and analyzed by geostatistics, mainly those related to Nitic and Ferralic/Oxic soil horizons. Three selected soil profiles under no-tillage and fallow […]

Navigation recipients of the global positioning system (GPS), widely used in the agricultural sector, in general, have a positional accuracy of < 10.0 m. In systematic soil sampling, sub-samples should be collected within a radius of not more than three meters from the central georeferenced point. In this technical note, precision and accuracy of this equipment were contrasted with the requirements of systematic soil sampling. An area of approximately 17 ha, on Campus I of the University of Passo Fundo, […]

Non-symbiotic diazotrophic bacteria (NSDB) influence plant growth through biological nitrogen fixation and also production and release of plant growth-regulating substances. The aim of this study was to evaluate the density and phenotypic diversity of this bacterial group in fragments of the “Reserva Biológica Serra dos Toledos” and surroundings, in Itajubá/MG. This reserve is located in the environmental protection area of Mantiqueira and represents an important recharge area and shelter for endemic flora and fauna. Topsoil samples were collected in areas […]

Soil penetration resistance (PR) and the tensile strength of aggregates (TS) are commonly used to characterize the physical and structural conditions of agricultural soils. This study aimed to assess the functionality of a dynamometry apparatus by linear speed and position control automation of its mobile base to measure PR and TS. The proposed equipment was used for PR measurement in undisturbed samples of a clayey “Nitossolo Vermelho eutroférrico” (Kandiudalfic Eutrudox) under rubber trees sampled in two positions (within and between […]

Soil compaction is one of the processes responsible for soil physical degradation that may result in the loss of sustainability of agricultural production. Therefore, it is important to have instrumental strategies to quantify soil physical properties that are influenced by soil compression and used to assess soil quality. The objectives of this study were to: (i) develop an inexpensive pneumatic consolidometer, (ii) evaluate its functionality by the study of the compressive behaviour of a sandy clay Rhodic Hapludox under no-tillage, […]

The intensive traffic of agricultural machinery of cultivation and harvesting operations of sugarcane can promote soil compaction and affect crop yield and longevity. One of the ways to evaluate soil degradation due to compaction is by analyses of soil compressibility and least limiting water range. The objective of this study was to evaluate the effect of sugarcane cultivation on pre-compaction pressure (sp), laboratory-determined soil penetration resistance (LPS) and on the least limiting water range (LLWR) of a cohesive Yellow Ultisol […]