Selective logging may become a form of sustainable use of Amazon forest ecosystems since most part of the forest biomass is maintained and the impacts on the exploited area are lower than in comparison to those under other land uses. The objective of this study was to evaluate the effects of selective logging on some soil physical characteristics. The study area lies about 80 km north of Manaus and the vegetation is a humid tropical rainforest. Seven to ten trees/ha (DAP > 55 cm) […]

The susceptibility of soils to compaction, measured by the Proctor test, decreases with increasing soil organic matter (SOM) content. For a given energy level, with increasing SOM contents the maximum obtained density decreases and the corresponding critical moisture content increases. Due to its low density, elasticity and deformation susceptibility, straw is potentially able to dissipate applied loads. This study was conducted to evaluate the SOM effect on the soil compaction curve and to evaluate the ability that mulch has to […]

Minas Gerais state is the largest coffee producer in Brazil. The state contributes with over 50 % of the total production, which is for the most part cultivated in the Cerrado region. This region is outstanding in coffee production due to the advanced technology in mechanization. Consequently, the machine traffic that the soils are subjected to causes concern because of the possibility of widespread soil compaction. Our objectives were (a) to propose load support capacity models to a typical dystrophic […]

Different sugarcane management systems on soils of coastal tablelands can cause alterations in their original soil structure. Effects of the different sugarcane management systems on the properties of a cohesive Yellow Argisol were studied in four areas of the Triunfo sugar mill in Alagoas State, Brazil. The treatments consisted of a site with and without cultivation irrigation each, one site with vinasse application and another under undisturbed native forest. Samples were collected at depths of 0-0.2, 0.2-0.4 and 0.4-0.8 m to […]

Soil compaction has led to reduced soybean yields, but the critical bulk density above which the yield decreases are poorly documented. Thus, this work aimed to evaluate the soybean yield (cv. Embrapa 48) in relation to the relative bulk density (Dsr) of a sandy loam (LVd) and a clayey Oxisol (LVef). A greenhouse experiment was carried out in 2001/02 with samples collected at the 0.0-0.2 m layer, sifted through a 4.0 mm sieve, fertilized and compacted in 0.03 m layers in 0.20 high […]

Soil micromorphological studies enable a detailed observation of the modifications in soil pore structure and space imposed by cultivation and agricultural machinery traffic. This study tested the hypothesis that compaction caused by machinery affects the form and class distribution of pores in a distinct way and that such alterations can be used as soil quality indicators. The objectives of this study were to evaluate and quantify, through micromorphological studies, the modifications in porosity caused by biological activity (biopores) in a […]

The agricultural use of soils usually relies on the use of heavy machinery that cause soil compaction, affecting the amount of air and water available for plants. The present study was carried out in the year 2000 and aimed at studying the performance of aggregates of an Amazon Oxisol under mechanical compression and that were subjected to varying degrees of matric potential. Humid and undisturbed tropical forest soil samples were collected from the A horizon (10 cm deep) and B horizon […]

Increment in pasture productivity has been associated with the understanding of the soil behavior under compression. The objective of this research was to quantify (a) the compression curves and (b) the preconsolidation pressure of the soils under non-irrigated and irrigated short duration grazing systems. Ninety-six undisturbed soil samples were taken from the four successive pasture cycles of Tanzania grass (Panicum maximum Jacq.) in a Hapludalf. The samples were saturated in water and equilibrated at the matrix potential (y): -10 kPa and then […]

Soil compression curves are frequently used in compaction studies. These curves describe the relationship between the logarithm of applied pressure and the soil bulk density or void ratio. The preconsolidation pressure divides the soil compression curves into a region of recoverable and a region of unrecoverable deformations. Consequently, the preconsolidation pressure has been used as an estimate of soil load support capacity of partially saturated soils. The preconsolidation pressure is laboratory-obtained through the uniaxial compression test which requires sophisticated equipment. […]

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 […]