Volume 30, Number 2, 2006

In agriculture and environmental studies, the hydraulic conductivity equation, that is, the hydraulic conductivity (K) as a function of soil-water content (q), plays an important role in the resolution of practical problems related to irrigation, drainage, and leaching of nutrients and pollutants. In order to quantify and characterize this hydric soil property it is essential to obtain representative values that can be safely used in a number of applications. With the objective of characterizing the statistical behavior and of quantifying […]

Minas Gerais state is the largest coffee producer in Brazil. The state contributes with over 50 % of the total production, which is for the most part cultivated in the Cerrado region. This region is outstanding in coffee production due to the advanced technology in mechanization. Consequently, the machine traffic that the soils are subjected to causes concern because of the possibility of widespread soil compaction. Our objectives were (a) to propose load support capacity models to a typical dystrophic […]

The preconsolidation pressure, despite the difficulties inherent to its measurement, provides a useful measure of the soil mechanical state for soil management and the planning of mechanization systems. The estimation of the preconsolidation pressure, based on easily measurable soil physical properties, may be relevant to solve some difficulties. The objectives of this study were: (a) to quantify the preconsolidation pressure and soil resistance to penetration measured in the laboratory and the field for a Haplustox under orange orchard, and (b) […]

Plant growth-promoting rhizobacteria (PGPR) can increase the productivity of several crops, including lettuce. The main objective of this study was to compare the root and/or root collar colonizing ability on the growth promotion ability. A method of evaluation of root colonization was tested with the main objective of speeding up screening trials for growth enhancement of lettuce. Additionally, the antagonism in vitro between rhizobacteria and the pathogen Fusarium sp. was tested to verify if growth promotion ability was determined by […]

Mining activities promote severe environmental degradation in many parts of the world, and revegetation techniques with diverse plant species have been used for rehabilitation of these areas. Studies on the occurrence, efficiency and diversity of key microbial groups such as leguminosae-nodulating, nitrogen fixing bacteria (LNNFB) are essential because they are involved in nutrient cycling processes and, therefore, to the sustainability of these areas. Aiming to evaluate the efficiency and phenotypic diversity of LNNFB, soil samples were collected from different bauxite […]

Several studies reveal that the substitution of native vegetation by agricultural systems results in decreases in the C and N soil organic matter pools. Aiming to test the hypothesis that management practices favoring organic residue inputs promote increases in the most sensitive organic matter pools, the present study intended to study areas of an organic management system of acerola fruit production and a conventional cultivation area cropped with carrot and beet in crop rotation with corn. These areas belong to […]

Nutrient dynamics of common bean grown under no-tillage system presents some particularities, requiring additional information for its adequate management. The present study was carried out on a typic Haplustox, in Selvíria County, MS, Brazil, with the objective of evaluating the effect of different levels and periods of nitrogen application on common bean (Phaseolus vulgaris L.) yield. A randomized complete block design in a 3 x 5 factorial scheme, with four replications was used. Treatments consisted of sidedressing urea at five […]

Sewage sludge application in forest plantations is one of the alternatives to solve the problematic final disposal of this residue. This research aimed at evaluating whether biosolids application improves soil fertility and the nutritional status of Eucalyptus grandis seedlings. The trial was installed in 20 cm diameter PVC columns with nine treatments (control, mineral fertilizer and increasing biosolid rates from 10 to 160 t ha-1) in four replications. The experiment lasted 12 months after planting the seedlings. Biosolids had a […]

Most soils in semi-arid Northeastern Brazil are considered phosphorus deficient. The great diversity of orders they belong to, however, indicates that they are not similar in relation to the concentrations of their different P forms. The distribution of phosphorus forms in 69 soils of the most common soil orders in the semi-arid region was evaluated in samples from the 0-20 and 20-40 cm soil layers. Phosphorus was determined by Mehlich-1 and by a sequential fractionation, through extractions with resin, NaHCO3, […]

Two Oxisol (Red-Yellow Latosol LBw and Dusky Red Latosol LVdf) toposequences in Paraná State, Brazil, were evaluated regarding the effect of different relief positions and parent material on mineralogical characteristics of the soil clay fraction. The clay fraction was investigated by X-ray diffraction, differential thermal analysis, thermogravimetry, and chemical analysis. Total Si, Al and Fe contents were determined after clay sample digestion with a 3:1 mixture of 36% HCl and 68% HNO3 acids. The Fe and Al contents were determined […]