Volume 22, Number 3, 1998

The experiment was carried out in greenhouse at the Soil Science Departament – Federal University of Lavras, Minas Gerais, Brazil. The objective was to study the effects of different CaSO4/CaCO3 ratios on the movement of nutrients in soil and cotton growth. The treatments consisted of four CaSO4/CaCO3 percentage ratios (100/0, 75/25, 50/50, 25/75 and 0/100), in an equivalent basis. A control treatment, without application of either CaSO4 or CaCO3, was also established. Substantial calcium and sulfate movement downwards was observed […]

Responses to phosphate fertilizing by vernalized garlic (Allium sativum, variety Roxo Perola de Caçador) were studied. To determine the calibration curve for phosphorus extracted with ion exchange resin, five soils of different textural groups, with and without organic fertilizer, were utilized. Two experiments, placed in 16 L pots, were carried out under greenhouse conditions, in the county of Botucatu, State of São Paulo, Brazil, from May to October, 1995 and 1996. Each of these experiments consisted of five soils at […]

Information about availability of boron in the Brazilian semi-arid soils is scarce. A greenhouse assay was conducted with 29 superficial samples (0-20 cm) obtained from representative mapped soils of the State of Ceará, Brazil, using sunflower as an indicator. The experiment was performed in 2.5 kg pots containing soil, fertilized with two boron levels (0 and 1.5 mg kg-1) with three replicates per treatment. The boron availability in the soil was determined by hot water, 0.05 mol L-1 hydrochloric acid […]

This study was conducted in order to verify the influence of induced chemical properties in standard kaolinite and samples of three soils from the State of Paraná, Brazil – Hapludox Haplohumox and Tropohumults – on the spectral reflectance obtained in laboratory using a spectroradiometer, adjusted from 400 to 2500 nm. The samples were treated with solutions of calcium acetate, sodium acetate and incubated with calcium carbonate and sodium bicarbonate. Higher spectral reflectance was observed in the samples treated with calcium […]

The best measures of crop residue quality for soil protection against erosion are the percentage of soil cover and its persistence on the soil surface. These two variables, in turn, may be strongly affected by soil tillage. This study was carried out in Rio Grande do Sul State, Southern Brazil (30°06’S; 51°39’W). Crop residue mulch persistence was evaluated over a fallow period, following the harvest of a soybean crop. Three conservation tillage methods (chiseling, disking, and no-till) were used as […]

This study was carried out at the Experimental Station “La Poveda” in Arganda del Rey (Madrid), with the following geographical coordinates: latitude 40º 19′ N; longitude 3º 19′ W Gr; and altitude 550 m. The main objective was to study the spatial variability of chemical and physical properties of a Typic Xerofluvent under three cultivation systems. Sampling for the study of spatial variability was performed according to an appropriate geo-statistical analysis in two directions. Spatial variability was observed with respect […]

The objective of this study was to evaluate the influence of different agricultural uses on alterations in the attributes of a medium-textured Latosol, in the region of cerrado and, in turn, on the formation of compacted and/or dense layers in the subsurface. In April, 1994, six sites were selected in the counties of Uberlândia and Monte Alegre de Minas, State of Minas Gerais, Brazil, where the soil was sampled in trenches: CC (Canadá Farm, cerrado vegetation); CP ( Canadá Farm, […]

The effects of continuous sugarcane cropping on the properties of a clayey Yellow Latosol were studied in the region of the Low Coastal Tablelands of Alagoas State, Brazil. Four sites were selected at Caeté mill, São Miguel dos Campos, AL, involving a native forest (Tn) and sugarcane fields cultivated for periods of two (T2), eighteen (T18) and twenty-five (T25) years. The soils were morphologically characterized and undisturbed samples of the A, AB, and BA horizons of each profile were collected […]

Aggregate size and the state of soil aggregation may be influenced by different soil management and cultural practices which lead to changes in soil organic matter content and biological activity. The objective of this study was to verify the relationship between organic carbon and the size and stability of soil aggregates in two planting systems (conventional and direct), three crop rotations (corn/wheat/corn, soybean/wheat/corn and soybean/wheat/soybean), under two soil sample preparation processes: use of 4 and 8 mm sieves before the […]

The educational process must be dynamic, with constant updating of course programmatic content, in order to adapt it to students’ expectations. The objective of this article is to present a method that has been applied in two discussion classes of the Soil Fertility course offered in the Agronomy and Forestry undergraduate programs at ESALQ/USP. The group study method was used in order to discuss the results of an experiment carried out in greenhouse at the Soil Science Department, to evaluate […]