Volume 32, Number 4, 2008

Soil management systems modify the spatial distribution of soil physical properties. The objectives of this study were to verify the spatial dependency and co-relationship of some soil physical properties by data fitting to individual and cross-semivariograms in an Oxisol (Typic Haplorthox) under no-till and conventional tillage, in Campo Mourão, state of Parana, Brazil. In April 2004, 128 undisturbed soil samples were collected in a 3 x 5 m grid, in the middle of the 5-0.15 m layer. The following soil […]

The physical, chemical and biological properties of soils of reconstructed areas after coal mining are altered. This study aimed to evaluate liming, mineral and organic fertilizers and revegetation effects on the physical properties of a reconstructed soil after open-pit mining. The experiment was carried out in a former mine in Lauro Müller County – SC, in southern Brazil, from 2001 to 2005. The site was mined in 1991 and reconstructed in 1995. A randomized complete block design was used, with […]

The soil use not always result in an ecological sustainable system. An intense and inadequate soil use leads to soil degradation. In this sense, this study aimed to investigate the influence of sewage sludge on the recovery of physical properties of a degraded Oxisol, cultivated for 2.5 years with eucalyptus (Eucalyptus citriodora Hook) and Brachiaria grass (Brachiaria decumbens), in Selvíria, MS, Brazil. Six treatments were evaluated in an experiment in a randomized block design with four replications: (1) Savannah; (2) […]

The objective of this study was to compare, in compacted soil condition, the aggregate stability after different crops rotations under no-tillage system and chiseling. The following crop rotations were repeated for three consecutive years under no-tillage: triticale (X Triticosecale Wittmack) and sunflower (Helianthus annus) as autumn-winter crops, together with pearl millet (Pennisetum glaucum), forage sorghum (Sorghum bicolor) and sunn hemp (Crotalaria juncea) in spring, preceeding soybean (summer crop). In the chiseling treatment the area was kept bare between the autumn-winter […]

Chiseling and cover crops can be used in the management of orchards with the purpose of improving soil physical conditions and reducing soil compaction. This study had the objective of evaluating the influence of chiseling on the development of cover crops and citrus trees and on soil physical properties in an orchard with a compaction history in a clayey Typic Haplorthox. The soil was chiseled at 0.30 m, followed by three soil cover crops: spontaneous vegetation, pigeon pea (Cajanus cajan), […]

The identification of impacts of mechanized sugarcane harvesting on the structure in different soil classes can be an important strategy to minimize compaction effects. The objective of this study was to evaluate the structural changes, preconsolidation pressure and least limiting water range (LLWR) in a Red-Yellow Latosol (LVA) and a Haplic Cambisol (CX), due to harvest operations at different periods during the sugar cane harvesting season. Undisturbed soil samples were collected in the layer 0 to 0.05 m to determine […]

The dispersion of Oxisol samples can be somewhat difficult due to highly stable microaggregates that are not always completely destroyed by chemical and mechanical dispersion. It is therefore important that chemical and mechanical methods are combined, along with the pretreatment of the sample, for complete and stable soil particle dispersion throughout the analytical procedures. Thus, this study aimed to evaluate the efficiency of mechanical dispersion (slow agitation with an orbital shaker – 30 rpm for 16 h, in the presence […]

Soil tillage promotes changes in soil structure. The magnitude of the changes varies with the nature of the soil, tillage system and soil water content and decreases over time after tillage. The objective of this study was to evaluate short-term (one year period) and long-term (nine year period) effects of soil tillage and nutrient sources on some physical properties of a very clayey Hapludox. Five tillage systems were evaluated: no-till (NT), chisel plow + one secondary disking (CP), primary + […]

To date, little is known about the dynamics of water and air in porous spaces of soils exposed to mechanical stresses, mainly when the pressure is located on the pre-consolidation line. This study aimed to quantify the changes in the porous spaces of an Acrisol under two tillage systems, submitted to increasing one-dimensional compression, emphasizing the bulk density and water retention at two water potential levels. Undisturbed soil samples were collected under conventional tillage (CT) and no-till (NT), with three […]

Knowledge about the fate of fertilizer nitrogen in agricultural systems is essential for the improvement of management practices in order to maximize nitrogen (N) recovery by the crop and reduce N losses from the system to a minimum. This study involves fertilizer management practices using the 15N isotope label applied in a single rate to determine the fertilizer-N balance in a particular soil-coffee-atmosphere system and to deepen the understanding of N plant dynamics. Five replicates consisting of plots of about […]