Volume 22, Number 1, 1998

Soil spatial variability of phosphorus, potassium, and organic matter was studied in different soils and management systems, in two counties: a) Eldorado do Sul, State of Rio Grande do Sul, Brazil, on a Dark Red Podzolic-Kandiudult (conventional tillage, no-tillage, minimum tillage, and pasture), using a grid sampling of 1 x 1 m and at depths of 0-0.05 and 0.05-0.20 m; b) Passo Fundo, State of Rio Grande do Sul, Brazil, on a Dusky Red Latosol – Hapludox (conventional tillage and […]

A field experiment was carried out to study the effects of potassium fertilization and time of harvesting on canola seed yield. The soil was a Red-Yellow Latosol (Hapludox), and the experimental design was a subplot replicated four times in completely randomized blocks. Potassium levels (0 and 40 kg ha-1 of K) were applied in the plots, and the subplots consisted of 7 weekly harvests, starting 112 days after planting. Yield and yield components were evaluated at each harvest. Although no […]

Samples of 30 soils were taken with the objective of characterizing the Capacity Factor of Phosphorus (CFP) and its relation with several properties of soils of Entre Ríos, Argentina. Isotherms of adsorption and a quick test of P adsorption were estimated. Langmuir and Freundlich equations described the adsorption phenomenon satisfactorily. The maximum adsorption capacity varied between 46 and 716 mg kg-1 of P in the soil, considering that the soils analyzed have from medium to low CFP. The adsorption capacity […]

Gypsum is an amendment used to alleviate subsoil acidity. However, there are doubts about its use for acid soils that previously received applications of lime and fertilizers. There are also doubts on the use of gypsum in the cases of the use of high liming rates or for aluminum tolerant crop varieties. This paper describes a limestone and gypsum experiment conducted from 1987 to 1992 at the Tatui Experimental Station, State of São Paulo, Brazil. The experiment was on a […]

A greenhouse experiment was carried out during the period October, 1991 to December, 1992, to evaluate the mass flow and diffusion contributions on sulphur transport to corn roots in soil surface samples (0-20 cm) of three acid soils collected in Viçosa, Paracatu and Lassance, Minas Gerais State, Brazil. Originally, the soil samples presented 5.0, 1.2 and 1.4 mg dm-3 of available S, respectively, obtained by extraction with a Ca(H2PO4)2 solution containing 500 mg L-1 of P in HOAc 2 mol […]

A field experiment, located on a private farm close to Piracicaba, State of São Paulo, Brazil, was conducted on a severely eroded soil (Ultisol-Entisol association), which has been planted with sugar cane for the last 30 years. The objective was to characterize the spatial variability of soil and plant attributes. An area of 50 by 70 m was divided into 10 columns and 14 rows in a grid of 5 m, resulting in 140 sampling points. Soil samples were collected […]

In order to evaluate the viability of corn planting in a soil under reduced tillage, a field trial was conducted in Passo Fundo (Rio Grande do Sul, Brazil), in December, 1988. In the control plots, soil tillage consisted of chisel plowing and disking. In the other five treatments, tillage was done through a conjugated operation (chisel plow with a clod break roller). In the control and in one of the other treatments, the configuration of each line of the planter-fertilizer […]

The knowledge of intense rainfall magnitude is very important for the elaboration of hydraulic projects, management of hydric resources in engineering and structure dimensionality for the water erosion control on soil conservation. However, information about the rainfall intensity can only be obtained directly from pluviograms, which quite often are not available at the study site, where the presence of pluviometer data (rainfall of “one day”) is more common. In this case, the disaggregation of daily rainfall into 24 hour periods […]

With the objective of defining the typology and distribution of the predominant erosion processes in a “Água da Cachoeira” microwatershed, with 3.700 ha, located in the “Planalto Ocidental Paulista”, a survey, characterization and mapping of erosion was conducted. Areas with sheet erosion, sheet and rill erosion, deep rill and gully erosion, and badlands were delimited through photointerpretation and field work. Four large badlands connected to the drainage net, eight wide gullies with partial vegetation cover and several average gullies which […]

Corn grain yield is very responsive do Zn in Brazilian soils. A greenhouse experiment was conducted in the Crop Science Department of the Botucatu College of Agricultural Sciences to compare sources of Zn and their application to corn. Three plants were grown up to 45 days in 10 L pots filled with a Dark Red Latosol (Acrortox, 22% clay). The soil was limed to 70% of base saturation. Zinc was applied to corn seeds (90 g ha-1), in the seed […]