Use of microbiological properties on the evaluation of degradation/reclamation of an area under iron mining
01/Sep/2000
Different sites of an iron mining from Mariana, Minas Gerais, Brazil, were evaluated for determining the degree of their degradation or reclamation, using microbial activity of soil, spore numbers of arbuscular mycorrhizal fungi (AMF) and total count of fungi and bacteria. Each site contained a substrate characterized as flotation refuse (Rj), Soil without vegetation (SS), Subsoil (Ss), Subsoil with vegetation (SsV), site under recuperation (AR) and forest (MS), and was sampled at 10-25 cm. Establishment of grasses and “candeia” (Vanillosmopsis […]
Characteristic mean diameter of soil particles
01/Sep/2000
An empirical equation to represent the analytical soil particle-size curve is proposed. Based on this equation, a new expression was obtained to calculate the predominant mean diameter of soil particles, which represents the mean size of these particles. The equations can be applied, advantageously, in soil physics as well as in geological, geomorphological and sedimentological studies.
Effect of tillage and cropping systems on soil organic matter dynamics and atmospheric CO2 mitigation in southern Brazil
01/Sep/2000
In this study, a first order exponential model was adjusted to the experimental data of soil organic carbon (OC) and total nitrogen (TN) of a 9-year-old experiment in southern Brazil. Parameters of soil organic matter dynamics were determined and the soil OC and TN stocks simulated in a Paleudult soil under three tillage systems (conventional tillage: CT, reduced tillage:RT, and no-tillage:NT) and three cropping systems (oat/maize-O/M, oat + vetch/maize-O + V/M and oat + vetch/maize + cowpea-O + V/M + […]
Potential acidity estimated by pH SMP in soils of Pernambuco state, Brazil
01/Sep/2000
The determination of soil potential acidity (H + Al) extracted by the 0.5 mol L-1 calcium acetate solution is a routine analysis in Brazilian soil laboratories. However, due to analytical facilities, it is becoming a regular procedure to estimate the values of potential acidity using the equilibrium pH of the soil suspension with the SMP solution. The aim of this study was to look at the relationship between pH SMP and H + Al in soils of Pernambuco, in order […]
Estimate of nitrogen fertilization for corn under soil conservation tillage systems and cover crops
01/Sep/2000
The use of mineral fertilizers and legumes is the most important strategy used to supply nitrogen for cash crops. Since there is a risk of environmental pollution by nitrogen fertilization, it is very important to improve the approaches of nitrogen use recommendation to achieve sustainable agricultural practices. The organic matter content has been used as a parameter to estimate N availability, but in some cases it has been inefficient. In order to develop an equation to estimate N availability in […]
Use of size exclusion chromatography in the characterization of humic substances from an oxisol under liming effect
01/Sep/2000
This study evaluated the molecular weight (mw) as well as the proportions of humic and fulvic acid fractions in humic substances (H5) extracted with 0.1 M NaOH and a chelating (Chelex 100 chelating ion exchange resins) (Na form), via High-Performance Size Exclusion Chromatography (HPSEC). Samples of a Dusky Red Latosol were collected from three areas: under orange-cultivated forest with and without liming. Standards of sodium polystyrene sulfonate and acetone were used to calibrate the molecular weight and retention time ratio. […]
Electrical conductivity, ph, and potential acidity in soils treated with solid urban waste compost
01/Sep/2000
This paper reports the effects of applying solid urban waste compost to 21 acid soils and five alkaline soils on the electrical conductivity (EC), pH (both in CaCl2 0.01 mol L-1 and in water), and potential acidity (H + Al). The compost was collected at São Matheus Treatment Plant, São Paulo. In acid soils, the compost was applied with and without mineral fertilizers and dolomitic lime (to reach 70% of base saturation). Lime was substituted by gypsum in alkaline soils. […]
Estimation of potential acidity by pH SMP in soils from Northeastern Brazil
01/Sep/2000
In this study the relationship between the pH SMP and H + Al concentrations was evaluated, in order to establish an equation for estimating the potential acidity of soils from Northeastern Brazil. The H + Al concentration (calcium acetate 0.5 mol L-1, pH 7.0) and pH SMP were analyzed in 81 soil samples. Soil carbon content ranged from 1.8 to 35.6 g kg-1, and clay content varied from 60 to 590 g kg-1. The equation H + Al = 31.521(pH […]
Chemical properties of a “Terra Roxa Estruturada” soil, inluenced by winter plant cover and organic and mineral fertilization
01/Sep/2000
This study was carried out to assess the influence of winter plant cover on the chemical soil properties in a Structured Terra Roxa soil in Santa Catarina, Brazil. The plant cover consisted of an association of black oats (Avena stirgosa Schreb) with pasture turnip (Raphanus sativus L.) and organic fertilization using poultry manure and mineral fertilization. Soil samples collected in August 1994 and January 1995, at depths of 0-10, 10-20 and 20-30 cm, were analyzed for an experiment initiated in […]
Critical moisture content and maximum dry bulk density in response to soil management systems in a Dusky Red Latosol
01/Sep/2000
The term soil compaction refers to the compression of an unsaturated soil during which an increase of the bulk density of soil occurs in consequence of the reduction of its volume, due to the expulsion of the air caused by inadequate management. To study the effect of different soil management systems on maximum dry bulk density and optimum moisture content, an experiment was conducted in a Dusky Red Latosol of the Lavras (MG, Brazil) region, submitted to the following management […]