Volume 30, Number 6, 2006

The genesis of cohesive horizons in some soils is not well known yet and, in many cases, it is conflicting. The purpose of this study was to evaluate physical, chemical and mineralogical mechanisms that cause hardening in soils with cohesive horizons, fragipan and duripan in Brazilian Coastal Plain soils. Soil samples of two toposequences were sampled and the taxonomic classes of the soils were identified as Argisolic Eutrophic Red Latosol, Latosolic Dystrophic Yellow Argisol for the first toposequence, and Abruptic […]

The aim of this study was to evaluate the behavior of the soil line for different soil classes by using reflectance data with a spectroradiometer in the laboratory. Representative samples of the surface and subsurface horizons of 18 soil classes collected in a pilot area in Rafard county, southwest São Paulo state, were dried, sieved and accomodated for spectral reading. Data were computed in order to simulate TM-Landsat 3 and 4 bands and to draw the graphs. The findings showed […]

There are few studies on soils under slash-and-burn agriculture in settlements in Amazônia. The aim of this study was the soil characterization in the Apiaú Agricultural Colony, Roraima, and to evaluate changes in some soil chemical properties in function of the management systems and the impacts of burning to the soil properties. The studied areas were: pastures, cultivated with banana and maize, burned forest and natural forest. The samples were submitted to physical chemical and mineralogical analysis. The soils are […]

The low biodegradability of synthetic chelating agents used for phytoextraction poses a great environmental risk due to the potential for metal leaching. Natural chelating agents can be an alternative to synthetic chelates due to their rapid biodegrability. The study aimed to compare the performance of natural organic acids (gallic, citric, and oxalic) to synthetic chelates/acids EDTA, DTPA, and NTA for induced phytoextraction of Pb, Cu and Zn by corn (Zea mays) and velvetbean (Stizolobium aterrimum). Soil samples were contaminated to […]

The study of the spatial variability of soil attributes can help in the determination of a specific management strategy that enhances agricultural productivity. The present study aimed at the evaluation of a possible influence of the soil management on spatial variability of a Dystroferric Red Latosol (Oxisol) physical properties. The study was carried out in 2002, in three adjacent areas, in Lavras, Minas Gerais state, Brazil, with the following management systems: A1 – fallowing for three years; A2 – recently […]

Knowledge on rainfall erosivity (R) of particular sites is fundamental for soil loss estimation by the Universal Soil Loss Equation (USLE) and therefore highly important in conservation planning. In order to obtain the R value estimates for places where it is unknown, an artificial neural network (ANN) was developed for the state of São Paulo, and its accuracy compared with the Inverse Distance Weighted (IDW) interpolation method. The developed ANN presented a smaller mean relative error in the R estimation […]

Appropriate boron (B) availability in soils favors root growth, and a sufficient supply of this micronutrient is very important for adequate rice development and yield in upland fields, depending on the cultivars and soil type. This study aimed at evaluating the influence of B addition on growth of roots and shoot of three upland rice cultivars. The experiment was carried out in a greenhouse, in 10 L pots containing 8 kg of an Hapludox; the experiment was in a completely […]

Organic agriculture is an emerging activity in the upper mid São Francisco River Valley, requiring technologies that are in line with the principles of this agricultural system. A study was carried out at Embrapa Semi-Árido to evaluate the efficacy of natural phosphates applied to three regional soils (dystrophic Grey Argisol – PAGd, eutrophic Yellow Argisol – PAe and Vertisol – V) planted with melon (Cucumis melo) in pots accommodated on wooden benches. The factorial treatments (3 x 4) + 1 […]