The forms and availability of heavy metals in contaminated soils determine the uptake potential of plants and water contamination by leaching. In this study different methods of chemical extraction were used, in order to identify the forms of Pb, Cd, Cr, Ni, Cu, and Zn and evaluate the availability of these pollutants for sunflower (Helianthus annuus L.), black oat (Avena strigosa Schreber) (exotic species) and Bahiagrass (Paspalum notatum Flügge) (native species), as indicators, in soils of Pb mining and metallurgy […]

Eucalyptus grandis and other clonal plantations cover about 3.5 million ha in Brazil. The impacts of intensively-managed short-rotation forestry on soil aggregate structure and Carbon (C) dynamics are largely undocumented in tropical ecosystems. Long-term sustainability of these systems is probably in part linked to maintenance of soil organic matter and good soil structure and aggregation, especially in areas with low-fertility soils. This study investigated soil aggregate dynamics on a clay soil and a sandy soil, each with a Eucalyptus plantation […]

The use of humic (HA) acids together with mineral and organic fertilizers probably modifies the natve soil humic acids’In the São Francisco Valley, Northeast Brazil, organic acids have gain interest of growers using irrigated agriculture. But so far, the possible modifications of the native soil humic substances under application of organic acids along with mineral and organic fertilizers are not known. The objective of this study was to evaluate and characterize the qualitative changes in humic acids extracted from a […]

Nitrogen (N) is required in large quantities by corn and its supply causes technical concerns related to crop performance and profitability, and environmental concerns in view of the high risk of nitrate leaching. Results of 61 field experiments conducted through 13 years, in a cooperative effort of the Fundação Agrária de Pesquisa Agropecuária (FAPA) and the Universidade Federal do Rio Grande do Sul (UFRGS), were analyzed and interpreted aiming at establishing a N fertilizer indication for high corn yields, adjusted […]

Flooded soils are important sinks of atmospheric C, hence the effect of agricultural practices on their organic matter (OM) dynamics should be better understood. This study was carried out in an 11 year experiment at IRGA (Instituto Rio Grandense do Arroz) experimental station in Cachoeirinha, Rio Grande do Sul, southern Brazil. The main objectives of this study were to evaluate the effect of no-tillage (NT) on organic C stocks, on OM lability and on the physical protection of OM in […]

Structural changes caused by management systems to soil can result in compaction and may change crop root development. With the aim to evaluate the effects of the farming systems on the soil structure by qualitative (cultural profile) and quantitative (soil density) methodologies, a field study was carried out in Maringá, state of Paraná, Brazil (23 º 29 ‘ S, 51 º 59 ‘ W). A conventional tillage system with crop succession of corn (Zea mays L.) and soybean (Glycine max) […]

The structural modeling of spatial dependence, using a geostatistical approach, is an indispensable tool to determine parameters that define this structure, applied on interpolation of values at unsampled points by kriging techniques. However, the estimation of parameters can be greatly affected by the presence of atypical observations in sampled data. The purpose of this study was to use diagnostic techniques in Gaussian spatial linear models in geostatistics to evaluate the sensitivity of maximum likelihood and restrict maximum likelihood estimators to […]

Understanding the magnitude of B mobility in eucalyptus may help to select clones that are more efficient for B use and to design new practices of B fertilization. This study consisted of five experiments with three eucalyptus clones (129, 57 and 58) where the response to and mobility of B were evaluated. Results indicated that clone 129 was less sensitive to B deficiency than clones 68 and 57, apparently due to its ability to translocate B previously absorbed via root […]

Boron deficiency causes large productivity losses in eucalypt stands in extensive areas of the Brazilian Cerrado region, thus understanding B mobility is a key step in selecting genetic materials that will better withstand B limitation. Thus, in this study B mobility was evaluated in two eucalypt clones (68 and 129), under B sufficiency or B deficiency, after foliar application of the 10B isotope tracer to a single mature leaf. Samples of young tissue, mature leaves and roots were collected 0, […]

Soil air permeability (Ka