Volume 24, Number 4, 2000

A soil sampler was designed and constructed to extract and evaluate undisturbed 75 mm diameter core samples at a depth of up to 0.60 m. Soil sample quality was evaluated and compared using traditional methods. The sampler consisted of a removable polyvinyl chloride (PVC) standard sewage pipe to receive the soil, an aluminium encasing sleeve and a steel conic cutting, surrounded by an auger with three cutting chisels. The soil sampler was adapted to a specially-designed off-road vehicle (VAS). The […]

The hydric characterization of the soils of the Campus of the Faculdade de Ciências Agrárias e Veterinárias in Jaboticabal, SP, Brazil has certified that the Red Latosol presented the largest available soil water capacity and that the amount of water held at field capacity (0.01 MPa) and permanent wilting point (1.5 MPa) was better correlated to the clay and silt contents, as compared to the organic matter content and soil bulk density. Using the hydric characteristics of the soils, their […]

The effects of different weed control methods in coffee (Coffea arabica L.) on some soil physical quality indicators were studied. The essay was installed in 1977 at the EPAMIG Experimental station in São Sebastião do Paraíso (MG), Brazil, in a coffee plantation on a Dusky Red Latosol. Coffee cultivar ‘Catuaí Vermelho’ LCH 2077-2-5-99 was planted at 4x1m spacing. Mower (RÇ), coffee tandem disk harrow (GR), rotary tiller (RT), post (HC) and pre-emergency herbicides (HR) and hand hoe (CM), were used […]

The aim of this work was to evaluate the effects of human intervention, i. e., jungle clearing and introduction of pasture (Brachiaria sp), on the total-N and organic-C contents and humic acids, fulvic acids and humina fractions. This research was carried out in a forest near Porto Velho – Rondônia (Amazo Forest) and Senador Canedo – Goiás (“cerrado”). The soil samples were collected in 1995, from areas of primary vegetation and planted pasture, obeying a line with 24 points every […]

An experiment was carried out under green house conditions to evaluate the effects of the inoculation with arbuscular mycorrhizal fungi (AMF), associated with the addition of formononetin (5, 10 µ mol L1), quercetin and morin (5, 10 and 15 µ mol L1), on the growth and nutrient content of passion fruit plants in the phase of seedlings cultivated in sterile substrate and after transplanting to a non-sterile substrate. The fungi utilized were Glomus clarum (Gc), Glomus fasciculatum (Gf) and a […]

Physico-chemical characteristics of humic acids obtained from urban waste (AH-CRSU) and sewage (AH-LETE) produced in the city of Rio de Janeiro, were determined through elemental analysis, total acidity, spectroscopic methods and electron scanning microscopy. The analysis of structural traits revealed some differences between the humic acids investigated. The presence of aromatic moieties was confirmed with UV-Vis spectroscopy, with more substituted systems present in the AH-LETE. IR spectroscopy showed aliphatic groups in the AH and as more complex signals due the […]

This research was conducted to investigate the principal structural units from humic acids obtained from urban waste compost (AH-CRSU) and sewage sludge (AH-LETE) by pyrolysis – gas chromatography / mass spectrometry. The humic acids from sewage sludge presented most mono and diaryl esters with higher mass. The n-alcans in AH-LETE showed a shorter chain than AH-CRSU. Phthalate fragments were incorporated into the humic acid structures, probably due to an organic matter contamination by plastics. The aromatic compounds in the AH-LETE […]

Among the tools used to describe the ramified structure or the rugged and distorted surface of humic acids (HA), fractal geometry seems to be one of the most adequate to explain the conformation of humic particles (molecular aggregates). From the experimental point of view, fractal dimension (D) of natural systems may be measured through the transmitted light, not scattered or absorved (turbidimetry’τ’). The presence of fractals indicates that the system may be decomposed in parts, each part being a copy […]

The aim of this work was to evaluate the influence of P levels and arbuscular mycorrhizal fungi (AMF) on growth and mineral nutrition of Citrus limonia. The experiment was conducted under greenhouse conditions, with a completely randomized 6 x 3 factorial design, with six P levels (0, 50, 100, 150, 200 and 250 mg kg-1 of substrate), two species of AMF (G. etunicatum and G. intraradices) and a control without AMF, with three replicates per treatment, using 1.7 dm-3 pots. […]

Some of the leguminous tree associated to fixing bacteria and micorrizal fungi have good development in degraded soils. Aiming to evaluate the influence of these species on soil fertility level, dry matter production and the nutrient contents of litter originated from these plants were measured during 1995. The rate of litter decomposition was evaluated by analysing the material collected in 1995 and 1996. Homogeneous stands of Caesalpiniifolia mimosa (‘Sabiá’), Acacia mangium and Acacia holosericea established at the experimental station of […]