Volume 29, Number 4, 2005

The structure, consistence, porosity, clay films, hydraulic conductivity, and water retention of soils with Nitic horizons and soils with both Nitic and Ferralic horizons were studied in-depth with the objective of contributing to the ongoing discussion on problems with the classification of “Nitossolos” (Nitisols) in Brazil. The hydrophysical performance of the studied horizons is intimately related to the soil structure type and grade and to the amount and distinctness of the clay films. Horizons characterized as nitic (“B nítico”) presented […]

Rill erosion is characterized by concentrated surface water flow, with enough shear stress and detachment capacity to deform the rill and alter flow hydraulics, responsible for rill formation dynamics. The objective of this study was to evaluate flow hydraulic conditions that can provide important information on erosion relationships, soil erodibility and sediment transport in furrows of a recently-tilled Palleudult. Rills were pre-formed in a sandy clay loam soil with an average slope of 0.067 m m-1. Simulated rainfall with an intensity of […]

Dry mass production, decomposition rate and nitrogen (N) release were evaluated in a field experiment under seven cover crop types: pearl millet (Pennisetum americanum sin. typhoides), brachiaria grass (Brachiaria brizantha), sorghum (Sorghum bicolor L. Moench), pigeon pea (Cajanus cajan (L.) Mill sp), sunn hemp (Crotalaria juncea) and black oat (Avena strigosa Schreb), compared to a fallow and a traditional cropping system (control) in a cerrado soil (Uberaba-MG, Brazil). Among the tested cover crops, pearl millet and sunn hemp presented higher […]

High N concentrations in biosolids are one of the strongest reasons for their agricultural use. However, it is essential to understand the fate of N in soils treated with biosolids for both plant nutrition and managing the environmental risk of NO3–-N leaching. This work aimed at evaluating the risk of NO3–-N leaching from a Spodosol and an Oxisol, each one treated with 0.5-8.0 dry Mg ha-1 of fresh tertiary sewage sludge, composted biosolids, limed biosolids, heat-dried biosolids and solar-irradiated biosolids. Results indicated that […]

The rhizospheric microbial action, accelerating the degradation of compounds in the soil, is known as phytostimulation. It represents one of the main phytoremediation mechanisms in herbicide-contaminated soil. Tebuthiuron-tolerant plants, which are able to stimulate their rhizospheric microorganisms, could be highly interesting for the phytoremediation of this herbicide. This study aimed at evaluating the rhizospheric activity of four plant species with phytoremediation potential for tebuthiuron and to infer on the contribution of the roots to the process of decontamination of this […]

One of the best options for final disposal of sewage sludge is its use for agricultural purposes. Excessive heavy metal concentrations in sludge, however, pose a risk to the environment. It is therefore important to determine not only the availability, but also the distribution of such metals in different soil fractions as a result of sludge application. Our study aimed at evaluating both the redistribution of Zn among soil fractions and the Zn-DTPA available concentration in sludge-incubated soils. Samples of […]

The present study aimed to evaluate the effect of the vegetation type and the sampling time on urease activity in two different tropical soils (Rhodic Oxisols). The experiment was installed in a typic alumino-ferric Red Latossol and a typic distrophic Red Latosol under five different vegetations: pinus, eucalypt, citrus, soybean and corn. The soil samples were collected from April 1990 to March 1991 and the urease activity, total nitrogen and organic carbon were determined. The urease activity changed according to […]

This study evaluated the kinetics of urease hydrolysis in two different Brazilian soils (Rhodic Oxisols): a typic alumino-ferric Red Latossol and a typic distrophic Red Latosol. The trials were carried out to study the effects of air drying, soil sampling, storage conditions and temperature, pH, time of incubation, and substrate concentration on the urease activity. Results showed that best conditions for soil sample storage after air-drying for a 7-day period were at room temperature or at a temperature of 5 ºC. […]