Volume 28, Number 3, 2004

The objective of this study was to evaluate alterations in the physical soil quality of a Dystroferric Red Latosol (Typic Haplorthox) caused by chiseling, after thirteen years of no-tillage. The experiment consisted of two management systems: soil chiseling down to a 0.30 m depth (NTC) and no-tillage (NT). Undisturbed soil samples were collected at depths of 0-0.15 m and 0.15-0.30 m, and the soil water retention curve, the soil resistance to penetration curve, the soil bulk density, and the “Least […]

The effect of physical, chemical and biological soil attributes on the stability of wet aggregates of two Oxisols cultivated with annual crops under no tillage for over four years was evaluated. Soils samples were collected in the 0-10 cm layer of two areas in a 100 m square grid marked with a DGPS. One of the areas is located in Campos Novos Paulista county, SP, Brazil (22 º36 ‘ 11 ” latitude and 50 º00 ‘ 09 ” longitude) on […]

Soil management alters the physical soil properties and changes the soil air, water, and solute dynamics. Physical soil properties as affected by conservationist soil management systems were studied in a sandy loam Typic Hapludalf. The treatments were established on a soil that has been under no-tillage for 10 years, and consisted of: no-tillage soybeans, chisel tillage soybeans, reduced tillage Crotalaria, and bare soil without tillage. The evaluated soil properties were soil penetration resistance, bulk density, porosity, pore size distribution, saturated […]

Ley forming modifier soil structure, which, in turn, effects soil physical characteristics in the upper layer. The objective of this study was to evaluate soil physical attributes and grain yield in a typical dystrophic Red Latosol (Typic Haplorthox) located in Passo Fundo county (RS), Brazil, after eight years of mixed production cultivation (1993 to 2000). The effects of production systems integrating grain production with winter annual and perennial pastures under no-tillage were assessed. Four mixed production systems were evaluated: system […]

The effects of pH changes and sewage sludge application on the distribution of Cu, Mn, Ni, Pb, and Zn among exchangeable, organic, amorphous Fe and Al oxides, crystalline Fe and Al oxides, and residual fractions of two soils (and Eutrustox and a Ultipsamment) were studied in a greenhouse experiment carried out at the FCAV-UNESP, in Jaboticabal (SP), Brazil. The heavy metal contents in these fractions were related to those extracted with DTPA, HCl 0.1 mol L-1, Mehlich-1, and Mehlich-3 extractants […]

The use of industrial and city wastes with high heavy metal contents in agriculture have increased the need for obtaining the concentration of such elements that are available in the soil. Thus, a greenhouse experiment was carried out at the FCAV-UNESP, in Jaboticabal, São Paulo State, Brazil in order to compare analysis methods (DTPA, HCl 0.1 mol L-1, Mehlich-1, and Mehlich-3) to evaluate the Cu, Mn, Ni, Pb, and Zn availability for corn (Zea mays L.) plants in two soils […]

The application of sewage sludge into agricultural soils, as organic fertilizer or soil conditioner, is becoming an increasingly more attractive alternative. It is occurring because of the high costs and environmental impacts caused by other sludge disposal methods, besides the presence of plant nutrients and organic matter in the sludge and the need to reduce costs in agriculture. However, sewage sludge can contain heavy metals, pathogenic microorganisms, and toxic organic compounds. In order to study the impact of sewage sludge […]

The objective of this research was to evaluate a modified ion exchange resin method for Mn and Fe extraction from soils. Forty-four soil samples presenting low, medium, and high Mn and medium to high Fe concentrations were used. Maize and soybeans plants were grown as test plants in a pot experiment in a greenhouse. Soil samples were analyzed for Mn and Fe using the modified ion exchange resin, DTPA, AB-DTPA, Mehlich-1, and Mehlich-3 methods. The correlation coefficients between soil Mn […]