Volume 28, Number 2, 2004

The objective of this work was to study the distribution of K and Mg reserve in different sand fraction classes of soils from the Triângulo Mineiro region (Minas Gerais state, Brazil), emphasizing the potential to release non-exchangeable and structural forms of these nutrients to plants. Sites were chosen for sampling based on the different parent materials (sandstone – Bauru Group, Granite – Araxá Group, basalt – São Bento Group and sediments – Detritic-Lateritic-Tertiary Cover), weathering degree, and spatial lithology representation. […]

The present study evaluated the influence of halomorphic, hydromorphic, and sulfate reduction conditions on sand fraction mineralogy and on the geochemistry of three mangrove soils from the Iriri River estuary. Three representative soil profiles selected from a transect had their geochemical conditions characterized and their effects on the mineralogy of the soils were described. The mineralogical analyses (XRD and EDS) and the physicochemical (Eh and pH) conditions found indicate the occurrence of pyritization in the investigated area. The mineralogical soil […]

Soil color is one of the central attributes in soil classification because it is related to the organic matter content and iron oxide mineralogy. The objective of this study was to make an evaluation of the predictive capacity of soil color, as determined by diffuse reflectance techniques, to quantify hematite and goethite in different Brazilian latosols (Oxisols). The spectroscopy technique allowed separating yellowish and light colored samples from dark and red ones, indicating an increase in reflectivity with decreasing hematite […]

The replenishment of labile phosphorus (P) from less labile soil P fractions was evaluated after 10 successive resin extractions and incubation during four months. Soil samples from the A, B and Bw horizons of Latosols (Oxisols) and A and Bt horizons of Luvisols were collected from the upper, middle, and lower position in the ladscape of three toposequences of each soil class. The evaluation was based on sequential fractionation of soil P with resin, NaHCO3 (organic and inorganic fractions), NaOH (organic […]

Grass species, which are frequently used for rehabilitation of degraded areas, can establish root associations with nitrogen fixing bacteria thus contributing to the ecosystem’s sustainability. On the other hand, microbial diversity plays an important role in the resilience of biological processes, including N2 fixation. This study aimed at the phenotypic characterization of 72 diazotrophic Gram-negative bacteria. Samples were isolated from areas under different rehabilitation strategies after bauxite mining in Poços de Caldas, Minas Gerais, Brazil, and inoculated in NFb, Fam, and […]

The effects of soil physical and chemical properties related to the soil Phosphorus Buffering Capacity (PBC) on soil P critical levels, by Mehlich-1, Mehlich-3, and Bray-1 extractant solutions were studied in six soil samples of the State of Pernambuco and in plant shoot, for the cultivation of Brachiaria brizantha (Hoscht ex A. Rich.) Stapf. cv. Marandu. This research was carried out under greenhouse conditions with surface soil samples with different clay contents, to which P doses, defined by the soil solution […]

Increased Ca2+ concentrations in the root environment have been suggested to minimize salinity effects on plant growth. In this work, seedlings of two forage sorghum genotypes (Sorghum bicolor (L.) Moench), one salt tolerant (CSF 20) and the other salt sensitive (CSF 18), were exposed to two Na+ (0 and 75 mmol L-1) and two Ca2+ (0.65 and 2.60 mmol L-1) levels in nutrient solution, in a 2 x 2 x 2 factorial design. After seven days of salt treatment, the shoot and root dry matter as well as Cl–, Na+, […]

The analysis of quantitative geomorphologic characteristics is concerned with understanding the soil-landscape relationships, resultant of erosive processes on diverse structures and lithologies. The main objective of this study was to evaluate the morphometric characteristics of the drainage pattern and relief in second order watersheds of the Córrego Rico Watershed in Jaboticabal County, São Paulo State, Brazil, covered by Oxisols and Ultisols. The study was based on vertical aerial photographs in a 1:35.000 scale. Photointerpretation techniques were used to draw the drainage […]

This study aimed to evaluate physical and chemical alterations in a distrophyc Yellow Argisol (Ultisol) presenting loamy to clayey texture and a smooth relief, under different use at the “Favo de Mel” settlement, Sena Madureira county, Acre State, Brazil. At the beginning of the rainy season (October 1999), soil material was collected in the following land use: native forest (control), recently deforested (slash and burn); a two-year old crop of palm tree (Bactris gassipae); and a four-year old Brachiaria (Brachiaria […]

The effect of surface liming on acidity components in the soil profile under long-term no-tillage system is largely unknown. This study was carried out in a long-term experiment (21 years) initiated in 1978 on a Brown Latosol (Haplohumox) located in Guarapuava County, Paraná State, South of Brazil. The aim was to evaluate the effect of lime reapplication methods on soil acidity attributes of both solid and liquid phases. Treatments consisted of: no liming, lime broadcast over the soil surface with no […]