Pesticidas no perfil de solos em áreas de plantação de cebolas em Ituporanga, SC

Abstract

RESUMOObjetivou-se com este trabalho avaliar as concentrações de resíduos de pesticidas no perfil do solo sob cultura de cebola, no município de Ituporanga, em Santa Catarina. Coletas de amostras foram realizadas nas profundidades de 0 a 20, 40 a 60 e 80 a 100 cm, em três áreas com plantação de cebola. Nestas áreas são realizadas rotações de cultura, abrangendo o milho, cebola, batata, feijão e beterraba. Três séries de amostragens foram realizadas nos períodos de 2006 e 2007, sendo coletadas, em um ano, amostras simples e, no outro, uma amostra composta. Para cada amostra foram determinadas as concentrações dos herbicidas: 2,4-D, alacloro, atrazina, diurom, dos fungicidas: azoxistrobina, metalaxil, metconazol, tebuconazol e do inseticida: lambda-cialotrina. Os resultados mostram que os ingredientes ativos considerados foram detectados nas três profundidades. Os fungicidas foram detectados com maior frequência na camada superficial. As concentrações variaram entre as áreas e entre as profundidades, de forma descontínua. O comportamento de distribuição das concentrações foi similar para todos os pesticidas. Supõe-se que a existência de caminhos preferenciais no perfil do solo seja o fator responsável pela ocorrência de concentrações elevadas em profundidade, de forma irregular. Palavras-chave: lixiviação, resíduos de pesticidas no solo, herbicida, inseticida, fungicidaPesticides in the soil profile in planting areas of onions in Ituporanga, SC ABSTRACT This study aims to evaluate the pesticide concentrations in the soil profile under cultivation of onion in the municipality of Ituporanga in Santa Catarina. Samples of soil were collected, at depths of 0-20, 40-60 and 80-100 cm in three areas. In these the maize, onion, potatoes, beans, and beets are used in crop rotation. Three sets of samples were collected in the period 2006 and 2007. In the first year single samples were collected and in the other year, a composite sample. For each sample, the concentrations of herbicide 2,4-D, alachlor, atrazine, diuron, of fungicides: azoxystrobin, metalaxyl, metconazole, tebuconazole and of insecticides: lambda-cyhalothrin were determined. The results show that the active ingredients were detected in three depths. The fungicides were detected more frequently in the surface layer. Those, in turn, were detected more frequently in the deeper layer. The concentrations varied among the areas and depths, occurring in discontinuous form. The behavior of the distribution of concentrations was similar for all pesticides. It is supposed that the existence of preferential paths in the soil profile is the responsible factor for the irregular occurrence of high concentrations in depth.

Atributos químicos do solo e lixiviação de compostos fenólicos após adição de resíduo sólido alcalino

“…De acordo com Pinheiro et al (2011) pesticidas submetidos aos processos de degradação e sorção nas partículas do solo são transportados na direção vertical pela água percolada e as quantidades transportadas serão mais expressivas se a percolação ocorrer em caminhos preferenciais, formados pelos macroporos.…”

Sustainability of the grey water footprint (GWF) for cultivation of onion in the Brazilian semi-arid regions

“…This means that this product has the largest amount of chemical applied during the year. Pinheiro et al (2011) report that a chemical to be considered suitable for crops should be lethal to the target pests, diseases and weeds but not non-target species including man, water and resources of soil. However, this is not the case, as the controversy of use and abuse of agrochemicals has emerged.…”

“…Damalas et al (2011), reported that the amount of agrochemicals that migrates from its area of application is directly affected by the specific chemical properties and are linked to their propensity to binding to colloids of soil, vapor pressure, water solubility, leaching potential, dilution in the water precipitated and its resistance to degradation over time. Pinheiro et al (2011) reported that the environmental factors are more dynamic in agrochemicals currently being used in the cultivation of onion. There is spatial and temporal heterogeneity, which influence the spatial distribution, either in the vertical direction or in the horizontal direction of the soil and time, occurring dissipation of the product, or by degradation, evaporation or absorption of bodies.…”

Leaching potential and residual effect of amicarbazone in soils of contrasting texture

“…Knowledge of the processes involved between the interaction of herbicides and the soil is of fundamental importance in order to minimize negative effects on the environment, especially water resources (BERGSTRÖM; BÖRJESSON;STENSTRÖM, 2011;PINHEIRO;MORAES;SILVA, 2011). Therefore, when herbicides are applied in the soil, they are exposed to the environment and may biodegrade due to the influence of physical, chemical and biological factors, or volatilized, adsorbed by soil colloids determining the residual effect and transported externally by soil surface runoff and leaching (LI et al, 2003;ANDREU;PICÓ, 2004;GUNASEKARA et al, 2007;VRYZAS;PAPADAKIS;PAPADOPOULOU-MOURKIDOU, 2012).…”