Alteraciones químicas y fitodisponibilidad de níquel en suelo tratado con lodo albañal

The alteration of soil chemicals and its influence on availability (DTPA extractant method) and phytoavailability (63Ni L-value, isotopic method) of Ni was studied in sewage sludge-amended soil at different pHs. The soil pHs were 4.3, 5.3 and 5.9 and the rates of sewage sludge (SS) 0, 15, 30, 45 and 60 Mg ha-1. The chemical and physicochemical soil characteristics were altered by the SS rate and increased the Ni availability and phytoavailability. The isotopic method (63Ni L-value) was more efficient in predicting the Ni phytoavailability that the Ni-DTPA extractant in soil pHs 5.3 and 5.9.

Carryover of Imazethapyr + Imazapic on Ryegrass and Non-tolerant Rice as Affected by Thickness of Soil Profile

Herbicides used in Clearfield(r) rice system may persist in the environment, damaging non-tolerant crops sown in succession and/or rotation. These damages vary according to soil characteristics, climate and soil management. The thickness of the soil profile may affect carryover effect; deeper soils may allow these molecules to leach, reaching areas below the roots absorption zone. The aim of this study was to evaluate the effect of the thickness of soil profile in the carryover of imazethapyr + imazapic on ryegrass and non-tolerant rice, sown in succession and rotation to rice, respectively. Lysimeters of different thicknesses (15, 20, 30, 40, 50 and 65 cm) were constructed, where 1 L ha-1 of the imazethapyr + imazapic formulated mixture was applied in tolerant rice. Firstly, imidazolinone-tolerant rice was planted, followed by ryegrass and non-tolerant rice in succession and rotation, respectively. Herbicide injury, height reduction and dry weight of non-tolerant species were assessed. There was no visual symptoms of herbicide injury on ryegrass sown 128 days after the herbicide application; however it causes dry weight mass reduction of plants. The herbicides persist in the soil and cause injury in non-tolerant rice, sown 280 days after application, and the deeper the soil profile, the lower the herbicides injury on irrigated rice.

Morphological, physical and pedogenetic attributes related to water yield in small watersheds in Guarapari/ES, Brazil

Soil characteristics related to the genesis, land use and management are important factors in water dynamics in watersheds. This study evaluated physical, morphological and pedogenetic attributes related to water yield potential in small watersheds in Guarapari, ES, Brazil. The following representative profiles were selected, morphologically described and sampled in area of Atlantic Forest domain: Lithic Udifolists, Oxyaquic Udifluventes, Typic Paleudults, Typic Hapludults, Typic Hapludox, Oxic Dystrudepts and Typic Endoaquents. Samples were collected in the soil profiles for physical analysis. Measurements of field-saturated hydraulic conductivity and soil penetration resistance were perfomed in some profiles, which were under different uses. The Endoaquents of Limão Creek can be considered efficient as temporary water reservoirs. However, the use of artificial drainage tends to reduce this effect. Differential erosion was detected by the sand texture on the surface of the Typic Paleudults due to the low degree of clay flocculation, slope, high resistance to the penetration and low hydraulic conductivity of the Bt horizon, making it necessary to adopt soil management practices to increase the water infiltration. Under pasture, mainly in the cattle trails where the trampling is more intense, there was high resistance to penetration in the superficial layers of the Typic Hapludults. The Typic Hapludox have the greatest potential for water yield in the small watersheds because of its greater extent in the headwaters and their morphological and physical characteristics, which can result in increased aquifer recharge.

Relação entre solo e floresta, no território de Roraima

Soil and basal area of natural forest are being investigated, in seven different localities of Roraima. The objective is to study the relation bettween natural forest and soil characteristics. Preliminary observations suggest influence of the depth and water balance of forest characteristics.

Variability of apparently homogeneous soilscapes in São Paulo state, Brazil: I. spatial analysis

The spatial variability of strongly weathered soils under sugarcane and soybean/wheat rotation was quantitatively assessed on 33 fields in two regions in São Paulo State, Brazil: Araras (15 fields with sugarcane) and Assis (11 fields with sugarcane and seven fields with soybean/wheat rotation). Statistical methods used were: nested analysis of variance (for 11 fields), semivariance analysis and analysis of variance within and between fields. Spatial levels from 50 m to several km were analyzed. Results are discussed with reference to a previously published study carried out in the surroundings of Passo Fundo (RS). Similar variability patterns were found for clay content, organic C content and cation exchange capacity. The fields studied are quite homogeneous with respect to these relatively stable soil characteristics. Spatial variability of other characteristics (resin extractable P, pH, base- and Al-saturation and also soil colour), varies with region and, or land use management. Soil management for sugarcane seems to have induced modifications to greater depths than for soybean/wheat rotation. Surface layers of soils under soybean/wheat present relatively little variation, apparently as a result of very intensive soil management. The major part of within-field variation occurs at short distances (< 50 m) in all study areas. Hence, little extra information would be gained by increasing sampling density from, say, 1/km² to 1/50 m². For many purposes, the soils in the study regions can be mapped with the same observation density, but residual variance will not be the same in all areas. Bulk sampling may help to reveal spatial patterns between 50 and 1.000 m.

Structural quality of polyacrylamide-treated cohesive soils in the coastal tablelands of Pernambuco

Water-soluble polymers are characterized as effective flocculating agents due to their molecular features. Their application to soils with horizons with structural problems, e.g, a cohesive character, contributes to improvements in the physical quality and thus to the agricultural suitability of such soils. The purpose of this study was to evaluate the structural quality of soils with cohesive horizons of coastal tablelands in the State of Pernambuco treated with polyacrylamide (PAM) as chemical soil conditioner. To this end, three horizons (one cohesive and two non-cohesive) of a Yellow Argisol (Ultisol) were evaluated and to compare cohesive horizons, the horizon of a Yellow Latosol (Oxisol) was selected. The treatments consisted of aqueous PAM solutions (12.5; 50.0; 100.0 mg kg-1) and distilled water (control). The structural aspects of the horizons were evaluated by the stability (soil mass retained in five diameter classes), aggregate distribution per size class (mean weight diameter- MWD, geometric mean diameter - GMD) and the magnitude of the changes introduced by PAM by measuring the sensitivity index (Si). Aqueous PAM solutions increased aggregate stability in the largest evaluated diameter class of the cohesive and non-cohesive horizons, resulting in higher MWD and GMD, with highest efficiency of the 100 mg kg-1 solution. The cohesive horizon Bt1 in the Ultisol was most sensitive to the action of PAM, where highest Si values were found, but the structural quality of the BA horizon of the Oxisol was better in terms of stability and aggregate size distribution.

State of the science and the way forward for the ecotoxicological assessment of contaminated land

Over the past two decades, soil ecotoxicologists have made strides in utilizing the basic concepts and advancements in soil zoology and ecology. They have applied the existing tools, and developed new ones to investigate how chemical contamination can affect soil ecosystems, including the degradation or destruction of soil quality and habitats or the diminishment of belowground biodiversity. Soil ecotoxicologists are applying a suite of standard protocols, originally developed as laboratory tests with single chemicals (e.g., pesticides), and further enhancing both the approaches and protocols for the assessment of contaminated lands. However, ecological relevance of some approaches remains unresolved. The authors discuss the main challenges for a coherent ecotoxicological assessment of soil ecosystems amid contaminated lands, and provide recommendations on how to integrate the effects of physical and chemical soil properties, the variations in the diversity of soil invertebrates, and the interactions among organisms of various trophic levels. The review examines new international approaches and test methods using examples from three continents (in particular research conducted in Brazil), and provides recommendations for improving ecological relevance of ecotoxicological investigations of contaminated lands.

Adsorção de glifosato sobre solos e minerais

Glyphosate, an enzyme inhibitor herbicide, has been widely used around the world in agriculture. Dr. John Franz from Monsanto Corporation (USA) discovered glyphosate in 1970. It has been showed that glyphosate is strongly adsorbed by inorganic soil components especially aluminium and iron oxides, and the phosphate group is involved in this interaction. The inactivation of glyphosate in soils can last for days or even months depending on soil characteristics. The addition of phosphate from fertilizers can displace glyphosate from the soils and this could be the cause of decreased productivity of some crops.

Concentrações de amônio na água da chuva e estimativa de emissão de amônia de rebanhos domésticos de Pinheiro e Viana, Baixada Maranhense

Rainwater samples (bulk deposition samples) were collected in Pinheiro and Viana. Rainwater pHs were higher than the range usually expected for unpolluted rain (5.0-5.6). The highest values were found in the beginning of the rainy season. High concentrations of ammonium found in the rainwater samples could probably explain the high pHs. Grazing animals and other human activities, combined with soil characteristics and climatic conditions can be the potential factors controlling the rainwater concentrations of ammonium in Baixada Maranhense.

Determinación simultánea de Cr, Ni y V en orina mediante et aas

A procedure for the simultaneous determination of Cr, Ni, and V in urine by electrothermal atomic absorption spectrometry (ET AAS) was optimized by factorial design, and performed at a pyrolysis and atomization temperatures of 1300 and 2500 ºC, respectively, using 15 µg de Mg(NO3)2 as chemical modifier. Characteristics mass of 14, 6 and 220 ρg and detection limits of the method of 0.07, 0.38 and 0.75 µg L-1 were obtained for Cr, Ni and V respectively. The methodology was validated using a Liphochek Urine Metals Control sample (Bio-Rad) (P=0.05). The methodology was applied to samples of voluntary Venezuelan people, not environmentally exposed to specific emissions, and results ranging from < LOD-1.1 and 1.3-3.3 µg L-1 was observed for Cr and V, respectively, and not detectable levels for Ni.

Sensibility analysis of the pearl model for pesticide leaching in the State of Mato Grosso do Sul, Brazil

For an accurate use of pesticide leaching models it is necessary to assess the sensitivity of input parameters. The aim of this work was to carry out sensitivity analysis of the pesticide leaching model PEARL for contrasting soil types of Dourados river watershed in the state of Mato Grosso do Sul, Brazil. Sensitivity analysis was done by carrying out many simulations with different input parameters and calculating their influence on the output values. The approach used was called one-at-a-time sensitivity analysis, which consists in varying independently input parameters one at a time and keeping all others constant with the standard scenario. Sensitivity analysis was automated using SESAN tool that was linked to the PEARL model. Results have shown that only soil characteristics influenced the simulated water flux resulting in none variation of this variable for scenarios with different pesticides and same soil. All input parameters that showed the greatest sensitivity with regard to leached pesticide are related to soil and pesticide properties. Sensitivity of all input parameters was scenario dependent, confirming the need of using more than one standard scenario for sensitivity analysis of pesticide leaching models.

Pedological characterization and land use and occupation: influences on water quality in a watershed located in the zona da mata (MG)

In order to verify the influence of class and use and occupation of land on water quality, it was performed the characterization and analyzes of land use and monitoring of seven springs inserted in a watershed located in the rural of Viçosa city - Minas Gerais (MG) state, in Brazil. Through soil analyzes, carried out in five different profiles, it was possible to identify three distinct pedological classes: Argisol, Cambisol and Latosol. Furthermore, the concentrations of Fe, Mn, Cu, Zn, Cr, Cd, Pb and Ni were identified in each of the horizons in the considered profiles. Water samples were collected and analyzed monthly, over eight months, twenty two parameters of water quality. Comparing the results of each survey, it was possible to identify a relation between water quality and land use in the round of the springs, considering color, BOD, DO, E. coli and Mn as the most affected parameters, influenced mainly by soil characteristics and the presence of a large percentage of pasture in the study area.

Swine wastewater associated with mineral fertilization on corn crop (Zea mays)

This study aimed to evaluate the agronomical and environmental aspects in corn, soil characteristics and leachate resulting from the material combination of swine wastewater and mineral fertilizer in the long run. The experimental area has a history of swine wastewater application for experiments conducted since 2006, this being the seventh crop cycle in the area. Four doses of swine wastewater (0; 100; 200 and 300 m³ ha-1) associated with presence and absence of mineral fertilizer were applied, consisting of eight treatments. The results obtained were subjected to variance analysis and means compared by Tukey test at 5% significance. We conclude that the swine wastewater can be partially used as an alternative fertilizer, since the P and Mn are complemented with specific fertilization. There must be carefulness about Fe+2, Cu+2 and Zn+2 accumulation in soil, and also to the concentrations of Fe+2, Cu+2, Zn+2, NO3- + NO2- and Na+ in leachate which exceeded the limits at the highest SWW applied levels.

Influence of tree species on the herbaceous understory and soil chemical characteristics in a silvopastoral system in semi-arid northeastern Brazil

Studies from some semi-arid regions of the world have shown the beneficial effect of trees in silvopastoral systems, by promoting the formation of resource islands and increasing the sustainability of the system. No data are available in this respect for tree species of common occurrence in semi-arid Northeastern Brazil. In the present study, conducted in the summer of 1996, three tree species (Zyziphus joazeiro, Spondias tuberosa and Prosopis juliflora: ) found within Cenchrus ciliaris pastures were selected to evaluate differences on herbaceous understory and soil chemical characteristics between samples taken under the tree canopy and in open grass areas. Transects extending from the tree trunk to open grass areas were established, and soil (0-15 cm) and herbaceous understory (standing live biomass in 1 m² plots) samples were taken at 0, 25, 50, 100, 150 and 200% of the average canopy radius (average radius was 6.6 ± 0.5, 4.5 ± 0.5, and 5.3 ± 0.8 m for Z. joazeiro, P. juliflora, and S. tuberosa , respectively). Higher levels of soil C, N, P, Ca, Mg, K, and Na were found under the canopies of Z. joazeiro and P. juliflora: trees, as compared to open grass areas. Only soil Mg organic P were higher under the canopies of S. tuberosa trees, as compared to open grass areas. Herbaceous understory biomass was significantly lower under the canopy of S. tuberosa and P. juliflora trees (107 and 96 g m-2, respectively) relatively to open grass areas (145 and 194 g m-2). No herbaceous biomass differences were found between Z. joazeiro canopies and open grass areas (107 and 87 g m-2, respectively). Among the three tree species studied, Z. joazeiro was the one that presented the greatest potential for use in a silvopastoral system at the study site, since it had a larger nutrient stock in the soil without negatively affecting herbaceous understory biomass, relatively to open grass areas.

Alterations of soil chemical properties by eucalyptus cultivation in five regions in the Rio Doce Valley

Little is currently known about modifications in edaphic characteristics caused by short-rotation eucalyptus and the impacts of these alterations on the sustainability of eucalyptus wood production. This study was carried out to identify theses changes at five sites of eucalyptus plantation in the region of the Rio Doce Valley, state of Minas Gerais, Brazil. Areas with more than three previous eucalyptus cycles, adjacent to pasture land or native forest, were chosen. Soil samples were collected and soil fertility analyzed by routine methods and other fractionation methods in order to measure alterations in the K, Ca and Mg contents as a consequence of eucalyptus cultivation. In the eucalyptus areas, reductions in the exchangeable Ca2+, Mg2+ and K+ contents and pH were observed and increased Al3+ and H + Al contents. Of all nutrients, only P contents (Mehlich-1 P) increased in the eucalyptus areas. The reduction in exchangeable forms and in medium-term soil nutrient pools indicates the need for higher nutrient rates than the currently applied in order to prevent nutritional limitations and soil nutrient exhaustion. After several eucalyptus rotations there was a recovery in the SOM content in comparison to degraded pasture soils, although not to the level of the native forest soil. The positive correlation between effective CEC and medium-term non-exchangeable Ca, Mg and K with SOM emphasizes the need for adequate fertilizer and plant residue management to sustain or even increase forest productivity in future cycles.