Volume 31, Number 6, 2007

Soil physical quality is essential for plant growth and sustainable agricultural systems. This study aimed to evaluate the efficiency of the least limiting water range (LLWR) to monitor soil compaction and soil physical quality for soybean, without and with irrigation. The study was carried out in an clayer Red Latosol (Oxisol) (21 ° 14 ‘ 53 ” S; 48 ° 17 ‘ 20 ” W; 540 m asl). The experiment was entirely randomized, in a 6 x 2 factorial scheme, with four repetitions. The compaction treatments were: T1 = without compaction; T2 = 1 pass of a 4 t […]

Total porosity and bulk density are strongly affected by soil management, which is reflects directly in agricultural productivity. In 2005, plant attributes were analyzed in an irrigated fall corn crop under no-tillage besides some soil characteristics (total porosity-TP and bulk density-BD), in a Haplic Acrustox on the Fazenda Bonança (Dahma Agricultural Company) in Pereira Barreto County, Sao Paulo State, Brazil (20 ° 40 ‘  12 ” latitude S; 51 ° 01 ’50 ” longitude W). The purpose of the study was to evaluate the variability, and linear and […]

Preconsolidation pressure is currently used as a tool in the study of the soil compaction process. The purpose of this work was to determine the layout and number of samples required for the determination of the preconsolidation pressure (sp) in a Red Latosol, as well as to characterize its variability and spatial distribution using classical statistics and geostatistics parameters. The study was carried out in an experimental farm area, in Lavras, Minas Gerais State, Brazil, conventionally tilled in the last […]

The size distribution, the quantity and stability of soil aggregates are important parameters to evaluate the soil structure, which plays a relevant role in soil-plant relationships. Vinasse when applied on soil stimulates microbial activity because of its organic matter content. This activity may increase mucilage production and improve the aggregation and soil structural stability. The objective of this study was to evaluate the aggregate stability in an Oxisol treated with different vinasse doses. The study was carried out at the […]

Soil suction has been regarded by soil scientists as an aspect of increasing importance and has been used as an important source of information in agriculture since early last century. Its knowledge helps improve human actions not only in aspects relating to vegetation and agriculture, but also concerning slope stability. Increasingly sophisticated tensiometers have been designed to measure soil suction. This study describes the state of the art in the evolution of tensiometers, aside from the development of a tensiometer […]

Chiseling is one of the mechanical practices that can be used in no-tillage (NT) soils in order to reduce soil bulk density, resistance to root penetration, and to increase water permeability. The effect of these changes on plant growth and consequently on grain yield depends on climatic conditions. In soils with ideal moisture conditions, the physical limitations tend to be less noticeable. This study aimed to analyze the changes in the physical and hydric properties of a chiseled Oxisol under […]

Temporal stability is described as the temporal persistence of a spatial pattern and is evaluated through correlation analysis of successive measurement data. In this study, the soil water storage was evaluated along two 76 m transects, each of them sampled at 20 points. The soil is an Oxisol (Yellow Red Latosol) under an 11- year-old citrus orchard, in Piracicaba-SP, Brazil. Soil water content, for the calculation of soil water storage in the layer 0.0-1.10 m, was obtained from weekly neutron probe readings at […]

Kaolinite is commonly found in fine fractions of tropical and subtropical Brazilian soils. Kaolinite can be verified by an X-ray diffractogram, made of a series of 00l peaks, at the distance of 0.715 nm. However, in some soils, major peaks can be found at about d = 0.720 nm, indicating halloysite or kaolinite-smectite (K-S) interstratified minerals. The objectives of this study were to verify this hypothesis and subsequently discuss soil genesis. Parent material and soil samples from the horizons A1, A2, E and Bt […]

Sodium iodide (NaI) and sodium polytungstate (SPT) solutions are being indistinctively used in density fractionation procedures of soil organic matter (SOM). This study aimed to evaluate these two solutions, adjusted to a density of 1.8 kg L-1 (NaI-1.8 and SPT-1.8), and particularly of SPT adjusted to densities of 2.0 (SPT-2.0) and 2.2 kg L-1 (SPT-2.2), with regard to their capacity of recovering the light fraction (LF) of SOM. A 20 g soil sample of the 0-5 cm layer of an Acrisol (PVd) and of a Ferralsol […]

In view of the toxicity of As for man and animals and the possibility of existence of a great number of contaminated areas it is imperative to know the total As content in soils considered uncontaminated and about As sorption processes in soils of variable charge. The objective of this work was to determine the total content and maximum capacity of As adsorption (CMADSAs) in Oxisols. The total content was determined by the USEPA 3051A method. The cmADSAs was determined by […]