Rafael da Rosa Couto

Accumulation and distribution of copper and zinc in soils following the application of pig slurry for three to thirty years in a microwatershed of southern Brazil

The application of pig slurry to soil can result in the accumulation of soil Cu and Zn, alter soil Cu and Zn fractions, and result in soil, surface water, and subsurface water contamination. This study evaluated the accumulation and distribution of Cu and Zn in soil profiles from 10 areas treated with pig slurry for 3–30 yr. A microwatershed within the municipality of Braço do Norte in the state of Santa Catarina and in the southern region of Brazil was studied. Hapludalf soil samples were collected at depths of 0.0–0.05, 0.05–0.10, 0.10–0.20, 0.20–0.30, and 0.30–0.40 m from 10 areas where pig slurry had been applied for 3–30 yr. The soil samples were dried, prepared, and analyzed to determine their chemical characteristics, particularly to quantify their Cu and Zn fractions. Although long-term pig slurry application resulted in greater available Cu and Zn concentrations in the surface soil layer, the migration of available Cu in the soil profile only occurred in areas that were subjected to more than 17 yr of slurry application. The application of pig slurry increased the available Cu and Zn contents in the surface soil layer; however, the available Cu in the soil profile increased in the areas with more than 17 yr of slurry application. Cu accumulation mainly occurred in the organic and mineral soil fractions, and Zn accumulation mainly occurred in the mineral fraction. Overall, Cu posed a greater risk for surface water contamination than Zn, especially in areas with more than 17 yr of pig slurry application.

Phosphorus fractions in soil with a long history of organic waste and mineral fertilizer addition

Applications for long periods of organic animal waste as a source of nutrients to crops can contaminate the soil and the surface and subsurface waters. This study aimed to evaluate how the utilization of organic waste, after successive applications, affects P fractions in the soil and consequently environmental contamination. In an experiment conducted for 8 years, totaling 12 applications with pig slurry manure (PSM), liquid cattle manure (LCM), swine deep bedding (SDB), and mineral fertilizer (NPK), 460; 505; 1.111; and 535 kg P∙ha−1 were added to the soil through PSM, LCM, SDB, and NPK, respectively. In September 2012, soil samples were collected in the layers 0.0 – 0.04; 0.04 – 0.08; 0.08 – 0.12; 0.12 – 0.16; 0.16 – 0.20 m, prepared and subjected to a sequential chemical fractionation of P. The 12 applications of pig slurry, liquid cattle manure, swine deep bedding and NPK fertilizer for eight years (urea + triple superphosphate + potassium chloride) provided accumulations of P fractions in the soil that were above the necessary for a proper nutrition to plants considering the available P fractions (AER + organic NaHCO3 + inorganic NaHCO3) in the soil. In addition, they showed that the use of swine deep bedding, followed by pig slurry, means higher levels of available P fractions in the soil. In this sense, the establishment of a dosage of organic waste to meet the nitrogen need of crops is not an environmentally appropriate parameter. It may cause P accumulation in the soil, increased absorption ability of plants and soil support, contributing to environmental contamination.

Espécies e atividade de alumínio na solução de solo arenoso com adição de dejetos líquidos de suínos

The objective of this work was to evaluate the effect of pig slurry applications on the exchangeable Al content, activity, and distribution of Al chemical species in the soil solution. Soil samples of a Typic Hapludalf were obtained from an experiment conducted during eight years, with 19 applications of 0, 20, 40, and 80 m3 ha-1 pig slurry. The soil samples were collected in stratified layers to determine exchangeable Al content and to extract the soil solution by the saturated soil paste method. The concentrations of the main cations and anions, dissolved organic carbon, and pH in the soil solution were determined. The distribution of the chemical species of Al and the activity of the Al3+ species were obtained through the Visual Minteq software. The application of pig slurry does not change the exchangeable Al content in the soil and the Al3+ activity in the soil solution. The low Al3+ activity in the topsoil layers does not present risk of toxicity for most crops. Pig slurry applications increase the proportion of the AlHPO4 and AlSO4 species in the soil solution, by increasing the concentration of soluble inorganic ligands.

Contribution of mineral N to young grapevine in the presence or absence of cover crops

The presence of cover crops in vineyards may decrease the availability of nitrogen (N) derived from fertilizer to grapevines. The present study aimed to evaluate the recovery of urea-15N and growth of young grapevines with and without natural vegetation in plant rows. The study was conducted in southern Brazil on one-year-old Chardonnay grapevines grown in soils with and without cover crops. The grapevines were subjected to the application of 40 kg N ha-1 in the form of urea-15N at 3% 15N atom excess. Dry matter yield, total N and fertilizer N were assessed in grapevines and soil layers. A small amount of N that is applied during the growing season of the grapevines is readily assimilated by the plants. The maintenance of cover crops in young vineyards may favor the maintenance of higher levels of N in the subsurface layers of the soil, contributing to the nutrition of the grapevines in the following growth cycles. The presence of cover crops reduced the importance of nitrogen fertilization in the growth cycle of grapevines because a large part of N absorbed by grapevines was derived from other sources. Nitrogen derived from the fertilizer applied to the soil in the presence or absence of cover crops was mainly concentrated in the newly-formed vegetative grapevine organs (leaves and shoots).

Vulnerability to contamination by phosphorus in a zero-order basin with a high density of pigs and a history of slurry addition: extrapolation of an index

AbstractThe application of phosphorus (P)-index methodology to assess the risk of water pollution from agriculture in river basins usually takes time and expends a great amount of resources. This study adapted the P-index methodology using digital mapping of key basin risk criteria for P loss in reference areas to evaluate the wider vulnerability to P loss in a zero-order basin with an intense concentration of pigs and with a history of pig slurry additions to the soil. The P content of eleven reference areas, where ten areas have received various applications of pig slurry and one area has no history of addition, was extrapolated to a zero-order basin using principal component analysis and analysis of hierarchical groupings. Estimated loss of soil and the distance between the P source and the watercourse were mapped using satellite images and in situ evaluations. The methodology of extrapolating was well correlated with a survey of P concentrations in land runoff and provides the potential to improve land management of those areas that are most vulnerable. Principal component analysis and hierarchical clustering analysis proved to be useful tools for the separation of areas with different slurry application times. Our results suggest that the P loss risk could be reduced through the adoption of soil conservation techniques such as reduced-tillage incorporating slurry and crop residue management to provide adequate soil protection, reduce the impact of raindrops and reduce erosion risk and transport of chemical pollutants to water bodies.

Copper and zinc fractions in the profile of an Inceptisol cultivated with apple in southern Brazil

The present study aimed to evaluate the accumulation and distribution of Cu and Zn fractions in the profile of an Inceptisol by application of fungicides with a previous history of apple cultivation in southern Brazil. Stratified soil samples (0.0 ? 0.025 m, 0.025 ?0.050 m, 0.05 ? 0.10 m, 0.10 ? 0.15 m, 0.15 ? 0.20 m and 0.20 ? 0.40 m depth) were collected in two apple orchards (8 years old and 18 years old), and in a native pasture area adjacent to the orchards. The soil was subjected to analysis of physical and chemical properties and to chemical fractionation of Cu and Zn. The fractions of soluble, exchangeable, organic, residual and total Cu and Zn accumulated in the topsoil (0.0 ? 0.025 m) of the orchards, being higher in the orchard cultivated for 18 years. Most Cu, especially in the topsoil of the 18 years old orchard, accumulated in the less stable organic fraction, which can potentiate toxicity to plants and transfer Cu e Zn to ground water. In deeper layers, Cu was also distributed in the residual and mineral fractions, which are more stable. Most Zn in the soil of the apple orchards was distributed in the mineral and residual fractions, which have low mobility and low potential toxicity to plants. Key words: Malus domestica, trace elements, toxicity, environmental contamination.