The use of herbicides is important to eliminate losses of weed interference on crops. However, excessive and inappropriate employment of these substances can cause serious consequences to the environment. In this way, the release system is very attractive for the weed control in the agriculture area. The aim of this work was to study a new delivery system for sulfentrazone herbicide encapsulated into the calcium alginate (Ca-ALG) microparticles for the weed control. The alginate microparticles were prepared via ionotropic gelation method and characterized by using optical microscopy, scanning electron microscopy, and thermogravimetric and differential thermal analysis. The controlled release (M
 t
 /M
 ∞
 vs. time) of the sulfentrazone herbicide was also analyzed using UV–Vis spectroscopy where we proposed different mathematical models to understand the mechanisms of controlled release of the herbicide. Furthermore, the release tests in field trial weed control were conducted using bioindicator species (Cucumis Sativus—Cucumber) to study the phytotoxicity evaluation caused by the Ca-ALG microparticles at different concentrations and their relationship with leaching depth. The results showed that the Ca-ALG microparticles exhibited good encapsulation efficiency (%EE): 76.11, 78.62, and 80.42% for the 4, 5 and 6 g L−1 concentration of herbicide. The release rates in the region I were 39.2, 46.5, and 35.5 mg s−1 for the 4, 5, and 6 g L−1 of herbicide concentration, respectively. The Ca-ALG microparticles containing sulfentrazone herbicide demonstrated potential application in controlled release platforms in agricultural as well as for controlling of weeds and minimization of leaching processes.

Controlled release behavior of sulfentrazone herbicide encapsulated in Ca-ALG microparticles: preparation, characterization, mathematical modeling and release tests in field trial weed control

This study evaluated remediation of the herbicide sulfentrazone in soils with three different mineralogies (kaolinite, hematite, and gibbsite) and three remediation sulfentrazone treatments (Canava...

Phytoremediation and natural attenuation of sulfentrazone: mineralogy influence of three highly weathered soils

Microbial bioremediation of pesticides in agricultural soils: an integrative review on natural attenuation, bioaugmentation and biostimulation

O ametryn e um dos herbicidas mais utilizados na cultura da cana-de-acucar, e pouco se conhece sobre as interacoes desse herbicida com os atributos dos solos da regiao canavieira do Nordeste brasileiro. Esse conhecimento antes da recomendacao do herbicida permite minimizar os efeitos negativos ao ambiente - em especial, aos recursos hidricos - e garantir a eficiencia no controle de plantas daninhas. Neste trabalho foi estimado o potencial de lixiviacao do ametryn, por meio de bioensaios e cromatografia, em cinco solos da regiao canavieira do Nordeste brasileiro: Neossolo Quartzarenico, Argissolo Vermelho, Espodossolo Ferri-humiluvico, Latossolo Vermelho-Amarelo e Cambissolo Haplico. Para isso, foram preparadas colunas com amostras dos respectivos solos. No topo dessas colunas foi aplicado o ametryn e, 12 horas depois, foi simulada uma precipitacao pluviometrica de 60 mm. Apos a drenagem da agua (72 horas apos aplicacao do herbicida), as colunas foram abertas longitudinalmente, para retirada de amostras de cada solo a cada 5 cm de profundidade. Numa parte dessas amostras fez-se a quantificacao do ametryn por cromatografia liquida de alta eficiencia e, na outra, foram realizados ensaios biologicos para confirmar esses resultados. A mobilidade do ametryn foi influenciada pelas caracteristicas fisico-quimicas dos solos, principalmente pelo teor de materia orgânica, textura e capacidade de troca cationica (CTC). Entretanto, isso nao pode ser considerado para o Espodossolo Ferri-humiluvico, cujas caracteristicas cimentantes restringem a infiltracao de agua e compostos orgânicos. A maior lixiviacao do ametryn ocorreu no Neossolo Quartzarenico, com maior concentracao do herbicida na camada de 5 a 10 cm de profundidade, em relacao a camada superficial de 0 a 5 cm, indicando possibilidade de perda da eficiencia agronomica e maior risco de contaminacao de aguas subterrâneas.

http://www.scielo.br/pdf/pd/v34n4/0100-8358-pd-34-04-00839.pdf

Ametryn Leaching in Soils from the Sugarcane Region in Northeastern Brazilian

One of the most damaging species in sunflower crops in Brazil is the hairy beggartick (Bidens pilosa L). The large number of seeds, the various vegetative cycles during the year, the staggered germination and the scarcity of selective and effective herbicides to control this weed in sunflower are some of attributes that hinder the control of hairy beggartick populations. Two experiments were carried out to evaluate the control of hairy beggarticks, as well as sunflower tolerance to herbicides. The treatments were as follows: S-metolachlor (1,200 and 2,400 g ai ha-1), flumioxazin (60 and 120 g ai ha-1), and sulfentrazone (150 and 300 g ai ha-1) and two controls (weedy and weed-free check). The selectivity of the herbicides was higher at low doses. Flumioxazin and sulfentrazone caused injury to sunflowers at the highest doses and mainly in sandy soils. Although S-metolachlor did not cause visual symptoms of injury, the higher dose reduced sunflower yield. The herbicides sulfentrazone and flumioxazin provided satisfactory control of hairy beggartick plants in both types of soils. S-metolachlor presented medium control of hairy beggarticks in clay soil; however, its efficiency was slightly higher when applied in sandy soil. The most efficient herbicide for controlling hairy beggartick plants was flumioxazin, followed by sulfentrazone.

/pdf/bidens-pilosa-l-asteraceae-control-in-sunflower-with-qe4xov4ifc.pdf

Bidens pilosa L. (Asteraceae) control in sunflower with residual herbicides

Sulfentrazone leaching potential is dependent on soil properties such as strength and type of clay, organic matter content and pH, and may result in ineffectiveness of the product and contamination of groundwater. The objective of this study was to evaluate sulfentrazone leaching in five soils of the sugarcane region in the Northeast Region of Brazil, with different physical and chemical properties, by means of bioassay and high-performance liquid chromatography (HPLC) resolution. The experiment was conducted in a split plot in a completely randomized design. The plots had PVC columns with a 10 cm diameter and being 50 cm deep, filled with five different soil classes (quartzarenic neosol, haplic cambisol, yellowish-red latosol, yellowish-red acrisol, and haplic gleysol), and subplots for 10 depths in columns, 5 cm intervals. On top of the columns, sulfentrazone application was conducted and 12 hours later there was a simulated rainfall of 60 mm. After 72 hours, the columns were horizontally placed and longitudinally open, divided into sections of 5.0 cm. In the center of each section of the columns, soil samples were collected for chromatographic analyses and sorghum sowing was carried out as an indicator plant. The bioassay method was more sensitive to detect the presence of sulfentrazone in an assessment for chromatography soil, having provided greater herbicide mobility in quartzarenic neosol and yellowish-red latosol, whose presence was detected by the indicator plant to a depth of 45 and 35 cm, respectively. In the other soils, sulfentrazone was detected up to 20 cm deep. The intense mobility of sulfentrazone in quartzarenic neosol may result in herbicide efficiency loss in the soil because the symptoms of intoxication and the amount of herbicide detected via silica were highest between 15 cm and 35 cm depth regarding the soil surface layer (0-10 cm), indicating that sulfentrazone should be avoided in soils with such characteristics.

/pdf/leaching-of-sulfentrazone-in-soils-from-the-sugarcane-region-9sag7td8ya.pdf

V.C. Melo

Papers

Leaching of Sulfentrazone in Soils from the Sugarcane Region in the Northeast Region of Brazil