Long-term experiments are essential for research about organic matter dynamics of soils. This paper reports results of an experiment installed in September 1985 on a Paleudult soil degraded under inadequate management for 16 years. The experiment was conducted at the Experimental Station of the Federal University of Rio Grande do Sul (Brazil) in Eldorado do Sul county. Three soil tillage methods (conventional tillage-CT, reduced tillage-RT and no-tillage-NT), three crop systems (oat/corn-O/C, vetch/corn-V/C and oat + vetch/corn + cowpea-O + V/C […]

The objective of this research was to evaluate the physical properties and organic carbon of a Typic Hapludalf in Pelotas, State of Rio Grande do Sul, Brazil, under different soil management systems on a farm. The assessed physical attributes were: soil bulk density, total porosity, macro and microporosity, particle size distribution, water dispersed clay, mean weight diameter of water-stable aggregates, and soil water infiltration, as well as organic carbon, in a factorial scheme in a completely randomized design with six […]

Different tillage systems cause changes in the chemical, physical and biological attributes of a soil, requiring modifications in the requirements of fertilization and liming. The aim of this work was to evaluate the effects of tillage systems on chemical and physical attributes of a soil, in a long-term experiment installed in 1985. Since then, the soil has been cultivated with annual cultures and submitted to six tillage systems: no-tillage (SD), disc plow (AD), moldboard plow (AA), heavy disc harrow (GP), […]

Soil management has an impact on soil cover and roughness, and, together with other variables, affects water erosion. In São José do Cerrito, State of Santa Catarina, Brazil, three simulated rainfall tests were evaluated during the soybean cycle March 2000 through June 2001 in combination with the five tillage systems: plowing + disking (bare soil) (BS); plowing + disking and soybean crop on dry oat residues (PD); chiseling + disking and soybean crop on dry oat residues (CD); soybean crop […]

Rainfall and runoff together are the active agents of water erosion, furthermore influenced by soil cover and roughness, crop and soil tillage. Compared to conventional tillage, water erosion is reduced in soil conservation tillage because this method is less intensive, preserves the cover longer, and sometimes increases soil roughness. Erosion losses (soil and water) of a clayey Hapludox with a slope of 0.09 m m-1 were evaluated in Chapecó, Santa Catarina State, Brazil, from November 1994 to October 1999 under natural rainfall. […]

The interest of surface liming of soils on no-tillage system is increasing. The objective of this work was to evaluate the effects of different lime particle sizes and doses applied during the implantation phase of no-tillage and in conventional tillage systems on soil pH and H + Al, Ca2+, and Mg2+ contents. The experiment was carried out in 1998/99, on the experimental farm of São Paulo State University in Botucatu, São Paulo, Brazil, on a Red Distroferric Latossol (Oxisol). A split plot […]

An increase in the use of winter mixed cover crops has been observed in Southern Brazil during the last years. As a new agricultural practice, it is important to evaluate its potential benefits in dry matter production and nutrient accumulation. A field experiment was carried out from 1998 to 2000, in UFSM (RS), on a Typic Paludalf soil. Black oat (Avena strigosa Schieb) + common vetch (Vicia sativa L.) and black oat + oilseed radish (Raphanus sativus L. var. oleiferus […]

Latosols (Oxisols) under cerrado vegetation have been intensively incorporated into the agricultural production process. However, studies involving soil quality in this environment are scarce. The objective of this work was to verify alterations on aggregation attribute indicators of soil quality, as a result of the management systems adopted for the native cerrado, and to select the best attributes indicating such alterations. The samples were collected at depths of 0-10, 10-20, and 20-40 cm from a typic Dystrophic Red Latosol (Oxisol) […]

The determination of potentially available phosphorus by chemical extractors is difficult in variable charge soils because there are several degrees of bound energy between phosphorus and colloids. The objective of this work was to estimate the minimum number of successive extractions with the Mehlich-1, Mehlich-3 and anion exchange resin (AER) methods to obtain values of potentially available phosphorus. Thirteen successive extractions were accomplished with Mehlich-1, Mehlich-3 and AER methods in samples of a Rhodic Hapludox under a no-tillage system and […]

All anthropic action causes changes in the environment. The objective of this study was the evaluation of alterations on the physical properties of a typical Brazilian Oxisol, caused by agricultural soil management. Undisturbed soil samples were collected along a 1m top layer of the soil profile in three use and management systems: natural forestry, non-irrigated and irrigated. These samples were used to determine the soil water retention curves and then the soil pore size distribution. After flooding, the aeration porosity […]