Volume 35, Number 3, 2011

The process of biological nitrogen fixation (BNF), performed by symbiotic nitrogen fixing bacteria with legume species, commonly known as α and β rhizobia, provides high sustainability for the ecosystems. Its management as a biotechnology is well succeeded for improving crop yields. A remarkable example of this success is the inoculation of Brazilian soybeans with Bradyrhizobium strains. Rhizobia produce a wide diversity of chemical structures of exopolysaccharides (EPS). Although the role of EPS is relatively well studied in the process of […]

Archeological sites are frequent in the Brazilian Amazon. The physical, chemical and morphological properties, due to anthropic influence, are quite different from surrounding soils, mainly in the uplands. Although several studies have been carried out to understand the magnitude of these modifications and their influence on the genesis of such soils, aspects such as the mineralogical properties need to be better described. This study aimed at evaluating the chemical and mineralogical properties of anthropic horizons (Au) of soils of upland […]

Map units directly related to properties of soil-landscape are generated by local soil classes. Therefore to take into consideration the knowledge of farmers is essential to automate the procedure. The aim of this study was to map local soil classes by computer-assisted cartography (CAC), using several combinations of topographic properties produced by GIS (digital elevation model, aspect, slope, and profile curvature). A decision tree was used to find the number of topographic properties required for digital cartography of the local […]

This study evaluated different environmental variables in the digital soil mapping of an area in the northern region of Minas Gerais State, using artificial neural networks. The environmental variables terrain attributes (slope and compound topographic index), the quickbird bands 1, 2 and 3, and lithology were evaluated. The importance of each of the variables in the classification was tested. The “Java Neural Network Simulator” was used with the backpropagation learning algorithm. For each dataset a neural network was created to […]

Cover crops may difffer in the way they affect rhizosphere microbiota nutrient dynamics. The purpose of this study was to evaluate the effect of mycorrhizal and non-mycorrhizal cover crops on soil phosphatase activity and its persistence in subsequent crops. A three-year experiment was carried out with a Typic Quartzipsamment. Treatments were winter species, either mycorrhizal black oat (Avena strigosa Schreb) or the non-mycorrhizal species oilseed radish (Raphanus sativus L. var. oleiferus Metzg) and corn spurry (Spergula arvensis L.). The control […]

Cowpea Vigna unguiculata [L.] Walp. is the main subsistence crop of the semi-arid region and a low-cost protein source, especially for poorer populations. The production of this crop in the Northeast is low due to the lack of agricultural inputs, among them, nitrogen fertilizer. Plant-growth promoting bacteria (BGPB) are being studied to maximize N2 fixation, provide nutrients such as P or phytohormones and inhibit diseases. The objectives of this study were to verify the viability of co- inoculation of cowpea […]

Chibui bari is an edaphic oligochaeta from the Amazon region, called “minhocuçu” in view of its large size (length up to 60 cm). Their castings, in tower-shaped mounds with a height of up to 30 cm and dry weight of 2 kg, are common on the soil surface of Acre State. The objective of this study was to compare nutrient availability, organic carbon concentration and microbial activity in Chibui bari castings with soil of the surroundings under secondary forest, rubber […]

Auxin-producing bacteria inhabit the roots of orchids and can bring benefits to the host plant. Plants of this family are multiplied by in vitro assimbiotic conditions and little is known about the role of these microorganisms for ex vitro acclimatization. Four auxin-producing rhizobacteria isolated from the specie Cattleya walkeriana were evaluated for their ability to promote survival and growth of in vitro germinated plantlets during ex vitro acclimatization. Partial sequencing of the 16S rRNA genes of bacteria cultures from root […]

The use of inoculants containing N-fixing bacteria for cowpea in the regions North, Northeast, and Central-West of Brazil is on the rise every year. However, in some cases, strains recommended for soybean have been used despite the existence of specific strains for cowpea. This study aimed to evaluate the performance of Bradyrhizobium strains recommended for soybean in cowpea nodulation and development. A greenhouse experiment was conducted with cultivar BRS Guariba, evaluating the soybean recommended strains: SEMIA 5079 (= CPAC15), SEMIA […]

The irregular disposal of coal combustion residues has adverse impacts on terrestrial ecosystems. Pioneer plants and soil invertebrates play an important role in the recovery of these areas. The goal of this study was to investigate the colonization patterns of terrestrial isopods (Oniscidea) in leaf litter of three spontaneous pioneer plants (grass – Poaceae, shrub – Euphorbiaceae, tree – Anarcadiaceae) at sites used for fly ash or boiler slag disposal. The experiment consisted of eight blocks (four per disposal site) […]