Land degradation in semiarid regions is a result of natural processes that can be induced or intensified by man through the inadequate use of natural resources, resulting in the degradation of vegetation, soil and water resources. Aiming to relate vegetation and soil degradation processes in the Agreste region of Pernambuco State, soil and vegetation in twelve representative plots were characterized as preserved, moderately degraded and degraded environments in the municipality of Jataúba. To study the vegetation, plants were stratified in […]

Intensive soil mobilization in the conventional tillage system has caused soil structure degradation, soil compaction below the arable layer, and decreased macroporosity. These changes resulted in reduced soil water infiltration rate and increased runoff, soil erosion and sedimentation in rivers and reservoirs. In the no tillage system the water erosion from the soil surface is practically controlled, and the terraces were eliminated by the farmers. Nevertheless, the surface flow is higher than it was in the conventional tillage system. With […]

The biodegradability and distribution of pesticides in the environment determine their pollution potential. The risk of contamination with atrazine herbicide was studied in an Ultisol under field conditions and complemented with a microcosm system study. This system allowed the use of 14C-atrazine under controlled conditions and to determine of the volatilization (0.33%), mineralization (0.25%) and leaching (4 to 11%) parameters, which are difficult to evaluate in the field. Ninety percent of the radioactivity remained in the soil, with 75% in […]

Gully erosion are very common in areas with gneiss basement rocks. Their development is strongly influenced by subsuperficial processes, although the surface ones are also important. This study aimed to investigate the subsuperficial erosion mechanisms of these gullies and to understand how mineralogy and texture could influence the saprolite erodibility. Some basic trials and erodibility tests were carried out in representative samples, with imphasis to especially the pin-hole test. The results showed that seepage erosion does not occur and that […]

The SWAT (Soil and Water Assessment Tool) model was applied to simulate the sediment yield in the watershed Ribeirão dos Marins, in Piracicaba, Brazil, for the biennial period of 1999/2000. The application of this model requires georeferenced input data, provided by an interface between the model and a Geographic Information System (GIS). The watershed was divided into sub-basins, and parameters were separately determined for each area. The simulated sediment yields were compared to the observed data of a gauge station […]

Soil and water losses by erosion were measured in forest ecosystems and were related to the calculated maximum tolerable soil losses. Main soil classes in the Coastal Plains of the region of Aracruz (ES) were studied, with the aim of obtaining indicators of management adequacy for this production system. The experimental plots were set on loamy/clayey Yellow Argisol (PA1), Haplic Plinthosol (FX), and moderately rocky Yellow Argisol (PA8). The slopes ranged from 2-8  %, 1-12  %, and 29-36  %, for each soil class. […]

Simple linear, multiple linear and nonlinear correlations between rainfall, runoff and rainfall-runoff erosivity parameters were studied, as well as soil losses caused by erosive rainfall on a Haplargids. Data were obtained in the period from 1986 to 1990 at the Experimental Station in Sumé, which belongs to the Universidade Federal da Paraíba – UFPB, Paraíba State, Brazil. Individual rainfalls registered in 136 rain gauges were analyzed for the determination of rainfall, runoff and rainfall-runoff erosivity parameters. The runoff volume, single […]

The climate of Southern Brazil is affected by climatic anomalies called “El Niño” and “La Niña”. During the first phenomenon, the precipitation volume is higher than normal. On the contrary, water deficits are observed during “La Niña”. Data of soil and water losses associated to these climatic anomalies are scarce, making their study the main objective of this work. An experiment on soil loss by natural rainfall was carried out on that account in Santa Maria, Rio Grande do Sul […]

Knowledge on soil shear strength can actually be a very useful tool for the control of slope and gully erosion, as well as for the introduction of mechanical conservation practices in agricultural soils. In order to evaluate the shear strength of five soils in the region of Lavras (MG) and its relation with the weathering rate, an experiment was carried out, using a direct shear machine which allows the collection of undisturbed soil samples. These samples were collected at a […]

The objectives of this work were to assess soil and water losses and determine interrill erodibility (Ki) of three soils with clayey texture: Typic Rhodudult (PE), a Typic Hapludult (PV) and a Rhodic Hapludox (LR) for the application of the WEPP (Water Erosion Prediction Project) model in Lavras, Minas Gerais, Brazil and to evaluate the relationship between Ki and some physical, chemical and mineralogical soil properties and surface characteristics. The experiment was set in a completely randomized block design, consisting […]