Kassio Ferreira Mendes

Quantification of the fate of mesotrione applied alone or in a herbicide mixture in two Brazilian arable soils

The effects of mesotrione, S-metolachlor, and terbuthylazine, applied in mixture, on soil biodegradation remain insufficiently researched. However, herbicide mixtures have been a common practice in agricultural systems in the last years. Understanding the fate of soil-applied herbicides may help on planning weed management tactics towards more sustainable and efficient weed control. Therefore, this study evaluated the fate of mesotrione alone and in mixture with S-metolachlor and terbuthylazine when applied to two contrasting arable Brazilian soils. Mineralization and degradation experiments were conducted using 14C-mesotrione alone or in mixture. From the 49-day laboratory incubation data, increased mineralization half-life of mesotrione was observed for the mixture of herbicides, ranging from a 4-day increase for the sandy loam soil to a 1-day increase in the sandy clay texture soils. Mesotrione degradation rate had a twofold increase in the sandy loam compared to the sandy clay soil. Two metabolites can be identified from mesotrione degradation, 4-methyl-sulfonyl-2-nitrobenzoic acid (MNBA) and 2-amino-4-methylsulfonyl benzoic acid (AMBA). Indices for the score of ubiquity in groundwater indicated mesotrione possesses leaching potential for both soils. Applying mesotrione alone or in mixture did not influence the amount of bound residues from mesotrione. However, mesotrione degradation rate was influenced by soil texture regardless if applied alone or in mixture. Mesotrione biotransformation was relatively quick, indicating that this herbicide has low persistence and, consequently, low residual effect on crops and weeds when present in similar soils to this present study.

Aminocyclopyrachlor sorption-desorption and leaching from three Brazilian soils

ABSTRACT This study aimed to evaluate the sorption-desorption and leaching of aminocyclopyrachlor from three Brazilian soils. The sorption-desorption of 14C-aminocyclopyrachlor was evaluated using the batch method and leaching was assessed in glass columns. The Freundlich model showed an adequate fit for the sorption-desorption of aminocyclopyrachlor. The Freundlich sorption coefficient [Kf (sorption)] ranged from 0.37 to 1.34 µmol (1–1/n) L1/n kg−1 and showed a significant positive correlation with the clay content of the soil, while the Kf (desorption) ranged from 3.62 to 5.36 µmol (1–1/n) L1/n kg−1. The Kf (desorption) values were higher than their respective Kf (sorption), indicating that aminocyclopyrachlor sorption is reversible, and the fate of this herbicide in the environment can be affected by leaching. Aminocyclopyrachlor was detected at all depths (0−30 cm) in all the studied soils, where leaching was influenced by soil texture. The total herbicide leaching from the sandy clay and clay soils was <0.06%, whereas, ∼3% leached from the loamy sand soil. The results suggest that aminocyclopyrachlor has a high potential of leaching, based on its low sorption and high desorption capacities. Therefore, this herbicide can easily contaminate underground water resources.

Emergence and Control of Rottboelia spp. in Different Months in Sugarcane Cultivation1

This study aimed to evaluate the control of Rottboelia spp. with the formulated mixture diuron + hexazinone + sulfometuron-methyl and the emergence of this weed in the months of April, May, June, July, August, September, October and November 2012 in sugarcane cultivation, cultivar RB867515. The experimental design consisted of randomized blocks, with treatments in a 4 x 4 factorial arrangement with four replicates for the months of April to November. The emergence tests used a randomized block design, in a 8 x 5 split plot arrangement with four replicates. The analyzed factors were the rates of the formulated mixture (diuron + hexazinone + sulfometuron-methyl), which consisted of: 1,809.00 + 510.00 + 43.50 g ha-1 (T2); 1,507.50 + 425.00 + 36.25 g ha-1 (T3) and 1,386.90 + 391.00 + 33.35 g ha-1 (T4), in addition to the control (T1) without application. Controls over 80.00% were found for the application performed in the month of November in evaluations at 30 and 60 DAA, regardless of the rate in use. All treatments were selective for the sugarcane cultivar RB867515. The tests conducted in the months of August, September, October and November showed the highest population density.

Pollutants Transformation and Metabolite Accumulation in Soils

Abstract After use by a wide range of activities and applications, and/or after made available by accidental sources, chemicals of various types remain as major pollutants in the main environmental compartments including soils. Organisms, including plants, and animals/humans, can be exposed to and impacted by soil-associated pollutants. Once in soils, the transformation of pollutants can be possible via chemical, photochemical, and surface-induced reactions. Eventually, the severity of toxicity of various metabolites mainly associated with the pollutant transformation products to parent material and/or organisms can differ. Considering recent literature this chapter: (1) introduces major pollutants encountered by the organisms or with their easy access to the soil medium, (2) overviews major mechanisms underlying transformation of pollutants in soils and the respective formation of metabolites, (3) highlights major techniques available for the determination of pollutants-transformation products and metabolites, and (4) lists the so far least explored aspects in the current context.

The Dissipative Potential of Gamma Irradiation in Residues of Imidacloprid and Thiamethoxam in the Postharvest of Common Beans: Effect of gamma rays in pesticides …

Gamma irradiation (60 Co) in postharvest of common beans (Phaseolus vulgaris L.), has already proven beneficial, regarding the prolongation of shelf life and physical, chemical, and organoleptic aspects of grains. However, few prior studies have investigated the effect of gamma irradiation on the dissipation of pesticides in foods, especially insecticides in beans. This study aimed to evaluate the waste dissipation of two insecticides, imidacloprid and thiamethoxam, used in the cultivation of common bean, a variety of Carioca, using gamma irradiation. Ground bean samples were spiked each insecticide in the laboratory at 3, 4, and 5 mg/kg, and were then irradiated at 0, 1, and 2 kGy per irradiator with a 60 Co source. Liquid chromatography-tandem mass spectrometry was used to quantify the insecticides. The irradiation promoted dissipation of thiamethoxam at 1 and 2 kGy doses, with the highest dissipation verified at 2 kGy. In general, at this higher dose of irradiation the reduction dissipation of thiamethoxam was 66% of the mean value found in the treatment without irradiation and ∼44% relative to the 1 kGy dose. Conversely, imidacloprid showed no effect of irradiation on waste dissipation, except in the treatment of 5 mg/kg at 2 kGy dose. From the results, it was concluded that the gamma irradiation might have applicability in dissipating thiamethoxam in real bean samples. PRACTICAL APPLICATION Pesticide residues remaining from bean cultivation, sensitive to optimal doses of gamma irradiation, can be transformed into other less harmful or nonharmful substances, increasing the quality of the beans before the food arrives at the consumers table. Irradiation of the grains after harvest also eliminates the need for application of other pesticides to preserve the grains during storage, as the technique is capable of eradicating deteriorating agents, such as microorganisms and insects.

Effects of Ametryn on Microbial Activity in Soil with Biofertilizer Addition

In recent years, pesticide application has increased worldwide due to the need for increased food production. In this way, understanding of the effects that these xenobiotic molecules can result in the soil microbiota becomes fundamental. Thus, this work aimed to evaluate microbial enzymatic activity by FDA, as well as quantify bacteria and fungi contaminated soil by ametryn herbicide. In addition, biofertilizer was added as a form of microbial biostimulation in order to cause enrichment of the affected site. The ametryn herbicide was chosen because it is widely used in sugarcane crops in Brazil, in the control of weeds, and is moderately persistent in the environment. It can be evaluated that the biofertilizer was fundamental in increasing the microbial activity of the soil, even in the presence of ametryn, probably contributing to its biodegradation. The estimation of the enzymatic activity by FDA, was essential for the evaluation of the increase of the microbial action, contributing to the verification of the active microbiota in the soil. It is suggested the application of biofertilizer in soils contaminated by ametryn, as a way to mitigate affected sites.

Glucose mineralization in soils of contrasting textures under application of S-metolachlor, terbuthylazine, and mesotrione, alone and in a mixture

Microbial adaptation may occur in surface soils under agricultural uses exposed to herbicides. However, little is known about herbicide mixture effects in the soil, especially in tropical regions like Brazil. The aim of this study was to evaluate glucose mineralization in soils of contrasting textures (sandy clay and sandy loam) from areas cultivated with maize under application of S-metolachlor, terbuthylazine and mesotrione, alone and in a mixture. The methodology was established according to the soil microorganisms: carbon transformation test with 14C-glucose solution (D-[U-14C] glucose) in biometric flasks. After the addition of 14C-glucose, the amount of 14C in cumulative CO2 of microbial respiration was measured several times during the 28-day incubation. For unamended soil control (without herbicide), microbial activity followed a similar behavior to SOIL AND PLANT NUTRITION Article Glucose mineralization in soils of contrasting textures under application of S-metolachlor, terbuthylazine, and mesotrione, alone and in a mixture Kassio Ferreira Mendes1*, Stella Andressa Collegari2, Rodrigo Floriano Pimpinato1, Valdemar Luiz Tornisielo1 1.Universidade de São Paulo Centro de Energia Nuclear na Agricultura Laboratório de Ecotoxicologia Piracicaba (SP), Brazil. 2.Universidade de São Paulo Escola Superior de Agricultura “Luiz de Queiroz” Piracicaba (SP), Brazil. *Corresponding author: kassio_mendes_06@hotmail.com Received: Oct. 4, 2016 – Accepted: Mar. 21, 2017 amended soil with herbicides in total CO2 released and accumulated, ranging from 23 to 27%. Overall, mineralization constant rate (k) values for all treatments were also similar, with an average value of 0.0038% CO2.d –1. Consequently, mineralization half-life times (MT50) were from 173 to 198 d. Microbial respiration for all treatments was slightly higher in the sandy clay compared with sandy loam soil; although soil samples with application of herbicides (alone and in a mixture) did not show decreased basal microbial respiration or mineralization rates of glucose. To corroborate these findings, additional research with different organic substrates and in cultures with different applications of herbicides are needed to prove the non interference of these herbicides on the microbial respiration in the soil.

Efficiency of bispyribac-sodium as ripening agent in the cultivation of sugarcane.

Objetivou-se com este trabalho avaliar a eficiencia do bispyribac-sodium como maturador quimico na cultura de cana-de-acucar variedade RB86-7515. O ensaio foi realizado no delineamento em blocos casualizados, esquema com parcelas subdivididas e 4 repeticoes. Os tratamentos principais (maturadores) foram compostos por testemunha T1 (sem aplicacao), T2, T3, T4, T5, T6 (20; 22; 24; 26 e 28 g ha-1 de bispyribac-sodium, respectivamente), T7 (15 g ha-1 de sulfometuron-methyl) e T8 (200 g ha-1 de ethyl-trinexapac). Os tratamentos secundarios (subparcelas) corresponderam as epocas de amostragens aos 15; 30; 45; 60 e 75 dias apos a aplicacao (DAA) dos maturadores. Foram considerados os parâmetros fitointoxicacao, produtividade de colmos, brotacoes laterais, solidos soluveis (%Brix), pol da cana (%Pol) e acucares totais recuperaveis (ATR em kg t-1). Os maturadores foram seletivos, onde nao foi constatado fitointoxicacao, independente do tratamento. Para as variaveis produtividade de colmos, Brix e ATR, nao houve diferenca significativa entre os diferentes tratamentos quimicos. Elevados indices de brotacoes laterais foram obtidos nos tratamentos com o bispyribac-sodium aos 60 e 75 DAA. Todos os tratamentos com maturadores apresentaram incrementos significativos nos indices de Brix e Pol, sem que houvesse decrescimo na produtividade e induziram ao aumento no teor de ATR aos 45; 60 e 75 DAA, em relacao a testemunha. O bispyribac-sodium, assim como o sulfometuron-methyl e ethyl-trinexapac foram eficientes na melhoria da qualidade tecnologica e apresentam potenciais para serem utilizados como maturadores na cultura da cana-de-acucar.

Sorption of oxadiazon in soils cultivated in the brazilian cerrado

The objective of this study was to evaluate oxadiazon sorption in different soils of the Brazilian Cerrado, highlighting the correlations of lethal doses of this herbicide capable of inhibiting 50% of the dry matter accumulation of the bio-indicator (LD50) among the chemical characteristics of the soil and its direct and indirect effects. The experiment was carried out in a greenhouse in a randomized block design and four repetitions. Each experimental unit consisted of a pot with increasing rates of oxadiazon and oat (Avena sativa), as the bio-indicator species. For sorption evaluation, washed sand and 22 soils (substrates) from Cerrado Brazilians Alliaceae cultivated areas were used. LD50 and sorption ratio (SR) = [(LD50soil - LD50sand)/LD50sand] to the substrates were determined. Pearson correlation analysis was performed between the chemical characteristics of the substrates and the LD50 of oxadiazon. A path analysis was quantified, to deploy only the significant correlations estimated in direct and indirect effects of the characters on LD50, which is a basic variable. A more pronounced LD50 (528.09 g ha-1) for the Cerrado soil sample resulted in higher SR (> 53.00), while in the washed sand substrate, LD50 corresponded only to 9.74 g ha-1 of the oxadiazon (available in soil). It was concluded that oxadiazon sorption is influenced by the chemical characteristics of the soils, highlighting the correlation with pH (CaCl2), magnesium content, aluminum, organic matter, organic carbon, and aluminum saturation.

Períodos de interferência de plantas daninhas na cultura do girassol

A interferencia de plantas daninhas na cultura do girassol pode reduzir significativamente a produtividade de aquenios. O objetivo deste trabalho foi determinar o Periodo Anterior a Interferencia e o Periodo Total de Prevencao a Interferencia da comunidade infestante sobre a produtividade de aquenios e de oleo da cultura do girassol. O experimento foi conduzido em campo, na area da Faculdade de Ciencias Agronomicas FCA/UNESP, na Fazenda Experimental Lageado, municipio de Botucatu (SP), no ano agricola de 2007/2008. O delineamento experimental foi o de blocos casualizados, com quatro repeticoes. Os tratamentos foram compostos por parcelas constituidas por periodos de controle e de presenca de plantas daninhas. Para os periodos de controle, a cultura foi mantida livre das plantas daninhas pelos periodos crescentes de 7, 14, 21, 28, 35, 42, 49 e 110 dias apos a emergencia do girassol. Para os periodos de convivencia, a cultura foi mantida na presenca da comunidade infestante pelos mesmos periodos. Foram avaliadas as seguintes variaveis: Diâmetro de capitulos, produtividade de aquenios, rendimento de oleo de girassol, densidade e materia seca das plantas daninhas e indices fitossociologicos. O periodo anterior a interferencia foi de 35 DAE da cultura para a produtividade de aquenios, sendo que o periodo total de prevencao a interferencia estendeu-se ate 24 DAE. Para o rendimento de oleo, o periodo anterior a interferencia foi de 25 DAE, enquanto que o periodo total de prevencao a interferencia prolongou-se por 14 DAE.