Volume 30, Number 3, 2006

Localized application of P in the soil has great influence on its availability because it reduces de adsorption reactions, precipitation and fixation, due to the lowered soil contact surface area. This study, carried out in a greenhouse, aimed to calibrate P soil concentrations for corn growth as affected by fertilizer placement. Samples of two Oxisols (LVAd and LVAm) were used. The treatment consisted of 14 combinations of 7 P rates, which were placed in holes in the upper mid part of […]

Land evaluation is a process that estimates the land use potential based on its properties. A large variety of analytic models can be used in this process. In Brazil, the two most widely used land evaluation systems are the “Sistema de Classificação da Capacidade de Uso da Terra” and “Sistema FAO/Brasileiro de Aptidão Agrícola das Terras”. Although different in several aspects, both require the crossing of countless environmental variables. ALES (Automated Land Evaluation System) is a computer program that allows […]

Soils formed from serpentinized rocks or serpentinites constitute a special group of soils on the earth surface. These rocks present ultramafic characteristics, with more than 70 % mafic minerals (iron and magnesium oxides). The mineralogy of serpentinites is poor in silica and aluminum and very rich in Mg. Only few studies have looked into the morphology, mineralogy, genesis and classification of soils developed on this type of parent material. In the humid-tropical climate of southwestern Minas Gerais state, three representative soil […]

Soil surface roughness is, among other factors, affected by soil tillage, cumulative rainfall and aggregate stability in relation to destructive water action. The soil surface roughness of a soil classified as a Haplumbrept was evaluated in an area where a water erosion experiment under natural rainfall has been carried out over the course of 15 years in the South of the Planalto Catarinense, Santa Catarina State, Brazil. The soil microrelief was characterized by the indices: roughness (RR), tortuosity (T) and limiting […]

Gliricidia sepium is a leguminous tree that has been used in alley cropping systems in the Northeastern semi-arid region of Brazil because of its good development under water stress conditions. However, little information is available on the effects of the introduction of this species into regional agroecosystems. The objective of the present study was to evaluate the influence of the distance of Gliricidia sepium plants on the characteristics of maize crop, soil properties and microclimate conditions in the semi-arid region […]

Interrill erosion occurs as a result of detachment of soil surface particles caused by raindrop impact and their transportation by overland flow (drag and suspension), which contain the organic matter and nutrients that are essential for agricultural production. An experiment was carried out to evaluate the effect of different soil cover types on the overland flow in interrill erosion in an area of sugarcane cultivation. The following situations were evaluated: bare soil; sugarcane straw mulch; sugarcane canopy cover; sugarcane canopy […]

Artificial changes in the properties of a soil contaminated with hexachlorobenzene were promoted in order to study the effects on the microbial community and the degradation of this compound. The soil samples were flooded or enriched with organic material or lime under laboratory conditions. The microbial activity and density as well as the total (mineralization) or partial hexachlorobenzene degradation (transformation into metabolites) were analyzed. The mineralization of 14C-hexachlorobenzene was analyzed by adding a 14C-hexachlorobenzene solution to soil samples, capturing the […]

Sewage sludge is an important source of nutrients for crops, although the heavy metal contents can limit its use in agricultural soils. The objective of this study was to evaluate the effects of doses of sewage sludge (from the Treatment Stations of Barueri (LB) and Franca (LF), São Paulo State, Brazil) on heavy metal concentration in corn leaves and grains. The experiment was carried out at the Experimental Area of the Embrapa Environment, in Jaguariúna, state of São Paulo, from […]

For the implementation and operation of the Brazilian Federal law on water resources of 1997 it is indispensable to use planning tools that take into account the effect of all activities or processes that cause or contribute to the loss of quality of a waterbody. For this purpose, the nutrient phosphorus was evaluated by the TMDL (total maximum daily load) process developed by the United States Environmental Protection Agency – EPA in the drainage area of contribution to the future […]