Volume 26, Number 1, 2002

Hematites were synthesized with different degrees of isomorphic substitution (IS) of Fe for Al to a maximum of 16Almol%.The minerals were characterized by X-ray diffraction, total chemical analysis, extraction of iron and aluminum soluble in ammonium acid oxalate (Feo+Alo), determination of the anion exchange capacity (AEC) and specific surface area (SSA).The results showed that the synthesis methods resulted in a minimum amount of impurities and that, in a general way, the foreseen values of isomorphic substitution were achieved.The SSA values […]

The arbuscular mycorrhizal fungi (AMF) are ubiquitous establishing symbiosis with a large number of plants in spite of soil contamination with heavy metals.This study aimed to evaluate AMF occurrence and diversity in soils of four locations cultivated with grass species and contaminated with heavy metals as a result of Zn extraction and industrialization. AMFs were found in all locations, with species predominance being affected by heavy metal concentration in soil. Twenty one species were identified, belonging to the following genus: […]

Besides its low cost, solar energy use in soil disinfestation presents no risks for human health and the environment. However, its effects on beneficial microorganisms are not well known. This study evaluated the effect of a solar collector and solarization on an indigenous population of arbuscular mycorrhizal fungi. Inoculum potential of mycorrhizae, determined by the most probable number method, decreased, respectively, 93 and 99% when soil was treated during 30days by solarization and solar collector. Mycorrhizal colonization of maize plants, […]

Wheat tiller number and survival and ear and grain production as affected by nitrogen supply were studied in cv.Embrapa 16 in three field experiments at Estação Experimental Agronômica (UFRGS), in Eldorado do Sul, RS, during 1995, 1997 and 1998.The first-year treatment consisted in applying 40kgha-1 of N in different plant stages (emergence to 5th leaf stage), followed or not by an extra N-supply at the 7th leaf stage. In 1997 and 1998, different N rates were applied at plant emergence, […]

The objective of this study was to evaluate the effects of P rates and placement on P uptake, leaf P use efficiency (PUE), and grain yield of corn (Zea mays) grown in a Yellow Argissol soil, typical of the coastal tablelands.Rates of 0, 45, 90, 135 and 180kgha-1 of P2O5 were applied in either the rows or broadcast.The study was carried out during the rainy season, from June to September of 1998, at Umbaúba Experimental Station, at Umbaúba (SE), Brazil.Broadcast […]

This study was carried out at EMBRAPA-CNPAF, Santo Antônio de Goiás (GO), Brazil, in a clayey Oxisol, under three soil tillage systems, from 1992 to 1998.Corn was grown in the summer and common bean in the winter, under center pivot sprinkler irrigation.The objective was to compare the values of pH, Ca, Mg, P, and K of the soil, sampled at different depths under no-tillage to those from soil under moldboard plough tillage (conventional) and harrow tillage.Forty replicates were collected at […]

Black oat/corn succession has been commonly used in the south of Brazil and N fertilization management is important for its success, especially under no-tillage. This study was carried out at the experimental area of the Department of Soil Science, at Federal University of Santa Maria (RS), Brazil, during 1999/2000, using a Hapludalf (sandy loam/clay loam).The objective was to evaluate the possibility to transfer, partially or totally, the amount of N, normally sidedressed to two applications – black oat tillering and […]

Two experiments were carried out simultaneously in a greenhouse to evaluate the effects of plant age and regrowth periods on soil and plant phosphorus critical levels for two tropical forage grasses. Treatments corresponded to the 2x5x5 factorial arrangement in the initial growth study, and the 2x2x5 factorial in the regrowth study.Those factorials consisted of two species (Brachiaria decumbens cv. Basilisk and Panicum maximum cv. Mombaça); five plant ages (14, 28, 42, 56, and 70days after emergence) in the initial growth […]

Seeds of common bean (Phaseolus vulgaris L.) with high P concentration, obtained from plants which had received foliar fertilization, were used in a greenhouse experiment to evaluate the effects of seed P concentration on growth and nodulation of common bean during the vegetative stage.The experiment had a 2x2x 3×3 factorial randomized block design with four replicates: two cultivars (Carioca and Rio Tibagi), two seed P concentrations (low and high, corresponding to 4.3 and 5.6mgg-1 for Carioca, and 4.8 and 6.3mgg-1 […]

This study compares the chemical composition of the solution and exchange complex of soil in a 3-year-old irrigated vineyard (Vitis vinifera L., Red Globe cultivar) with that of adjacent clearing in the native hyperxerophyllic ‘caatinga’ vegetation. The soils are classified as Plinthic Eutrophic Red-Yellow Argisol; according to Soil Taxonomy they are isohyperthermic Plinthustalfs. Detailed physiographic characterization revealed an impermeable gravel and cobble covering the crystalline rocks; the relief of this layer was more undulating than the level surface. Significant higher […]