Acidity is generally reduced in soils when organic matter is incorporated but the mechanisms of this alteration are still poorly understood. The objective of this study was to determine the relationship between the kinetics of organic material degradation and acidity alterations. Samples taken from the 0-20 cm soil layer (Ustic Dystropepts) were incubated with five sources of organic matter: green manure (Canavalia ensiformis D.C), cattle manure, vinasse, sewage sludge and peat, at temperatures of 20 or 30 ºC. The experimental […]

Studies with soil columns (Ø = 4 cm; h = 25 cm) were carried out under laboratory conditions in the years 1999 and 2000, in Londrina, using the Bw horizon of a Red Latosol. The following weed species were tested: Synedrellopsis grisebachii, Acanthospermum hispidum, Amaranthus hybridus, Leonotis nepetifolia, Parthenium hysterophorus, Ricinus communis, Galinsoga parviflora and Commelina benghalensis. Shoot extracts (3 g in 150 mL of water) were applied onto the soil surface with a lime top dressing and then leached […]

On a regional summit surface in the county of Piracicaba (SP) within the Peripheric Depression of São Paulo, formed of discontinued flattened tops, there is an abrupt transition between a Typic Hapludox and a Kandiudalfic Eutrudox, together with two stoneline layers. Using stratigraphical, mineralogical, and cartographic studies, this transition and the soil distribution of this surface were studied, correlating them with the different parent materials and the morphoclimatic model of landscape evolution in Southeastern Brazil. The Typic Hapludox was formed […]

Morphological, physical, chemical and mineralogical properties, as well as the weathering processes were studied in a Red Yellow Argisol (Aridic Kandiustalf) (well drained) and a Solodic Planosol (Aridic Haplustalf) (partially drained), developed from gnaisses, in a topossequence of the central semiarid region of Ceará State, Brazil. The study had the purpose of investigating the influence of soil locations in the landscape (internal drainage) and on the diversification of soil properties, as well as to study processes of surface transport and […]

The high availability of metallic ions in the soil, including Mn2+, may inhibit arbuscular mycorrhizal fungi (AMF), slowing down spore germination and, consequently, the mycorrhiza formation, therefore decreasing the symbiotic effectiveness. The aim of this study was to evaluate the effect of Mn2+ ions on spore germination in six AMF species of the genera Glomus, Acaulospora, Gigaspora and Scutellospora under in vitro conditions. Different Mn2+ doses (15, 30 and 75 mg kg-1) as MnCl2.4H2O were added to a washed sand […]

The climate of Southern Brazil is affected by climatic anomalies called “El Niño” and “La Niña”. During the first phenomenon, the precipitation volume is higher than normal. On the contrary, water deficits are observed during “La Niña”. Data of soil and water losses associated to these climatic anomalies are scarce, making their study the main objective of this work. An experiment on soil loss by natural rainfall was carried out on that account in Santa Maria, Rio Grande do Sul […]

The objective of this study was to evaluate the influence of addition of ammonium sulfate in mixture with urea on the volatilization of NH3-N. An experiment was carried out under controlled laboratory conditions at the Soil and Plant Nutrition Department (ESALQ/USP). The experimental design was completely randomized with five replications and five treatments. Each treatment was obtained by the mixture of urea (330 mg) with ammonium sulfate at different rates (0, 75, 150, 225 and 300 mg). The fertilizer mixtures […]

This experiment had the objective of assessing the influence of management practices (disk harrowing, Pueraria phaseoloides and mowing) on the soil’s bulk density and macro- as well as microporosity between the rows of rubber trees (Hevea brasiliensis) planted in 1992 in the highland of the State of São Paulo. A Dark Red Latosol, from Jaboticabal County and a Yellow Red Podzolic from Tabapuã County, São Paulo State were sampled at four depths (0-10, 10-20, 20-30 and 30-40 cm) in the […]

A micropedological study was carried out in rehabilitated soils after bauxite mining, in sites dating from 1981 to 1987, compared with the Yellow Latosol, as reference, to subsidize soil indicators of rehabilitation. The study was located in Porto Trombetas, district of Oriximiná, northwestern Pará State. Micromorphological techniques, using EDS/SEM microprobe, optical and scanning electronic microscopy, were used in combination with chemical and physical analysis, at 0-10 and 40-50 cm depths. The Yellow Latosol showed a strong development of microgranular structure, […]

Growth stagnation on native grassland during the winter season has stimulated the introduction of winter species in order to increase forage offer for animals in the State of Rio Grande do Sul, Brazil. To determine the nutrient losses by erosion as affected by different methods of native grassland improvement, an experiment was carried out at the Agronomic Experimental Station of the Federal University of Rio Grande do Sul, in Eldorado do Sul. A mixture of the winter forage species black […]