Norflurazon Mobility, Dissipation, Activity, and Persistence in a Sandy Soil As Influenced by Formulation

Abstract

Five ethylcellulose (EC) microencapsulated formulations (MEFs) of norflurazon were prepared and applied in soil to study their mobility, dissipation, activity, and persistence. The results show that the release into water of norflurazon from EC microspheres was retarded when compared with that of commercial herbicide. The mobility of norflurazon from MEFs into soil columns has been greatly diminished in comparison with that of its current commercial formulation (CF). Norflurazon distribution at different depths in the soil was higher in the upper ring (up to 50% of the initial application). In contrast, the residues from commercial norflurazon along the complete soil column were only about 2%. Degradation and bioassay experiments showed that the MEFs had greater persistence (t1/2 values were 7.72 and 30.83 weeks for CF and MEFs, respectively) and herbicidal activity than the commercial formulation. The use of these formulations can be advantageous, because they can minimize the risk of groundwater contamination and permit herbicide use at reduced rates, maintaining the desired concentrations of herbicide in the topsoil layer for longer periods of weed control.

Controlled release system for ametryn using polymer microspheres: Preparation, characterization and release kinetics in water

“…The low efficiency of encapsulation of bioactive substances in some microparticles could be related to the use of high concentrations of emulsifiers, as is the case for the PHB and PHBV microparticles, where poly-vinyl alcohol (PVA) is used in the preparation procedure. The emulsifier increases the solubility of the herbicide in the aqueous phase, and therefore reduces the association of the compound [44][45][46][47]. This could be useful in agricultural practices, since a controlled release system in which only 30% of the herbicide is incorporated within a carrier enables the fraction of the active compound that is not associated with the microparticles to be immediately released at the application site, where it acts rapidly, while the remaining fraction is progressively released with time.…”

Matrix-Based Fertilizers Reduce Pesticide Leaching in Soil

“…Microencapsulation is defined as the process of coating an active substance (molecules, solid particles, or liquid globules consisting of various materials), resulting in particles of micrometric size (Arshady 1999). Microencapsulated ethylcellulose formulations reduced alachlor loss by 54% compared with the commercial formulations (Dowler et al 1999;Fernández-Urrusuno et al 2000;Sopeña et al 2007). Commercial slow-release pesticide formulations have been encapsulated with a hydrophobic barrier often from various styrene compounds, combined with mono-or di-carboxylic acids anhydride carboxyl groups.…”

Polysaccharides as safer release systems for agrochemicals

“…This result indicates that the release process was governed by Fickian transport. Sopeña et al (2007) determined the influence of several variables on the ability of microspheres to reduce leaching of the herbicide alachlor in sandy soils in order to avoid contamination of underground water bodies. The microspheres were able to retard the release rate of the alachlor in relation to commercial formulation.…”

“…The release of herbicides from the carrier system is affected by the formulation parameters (Sopeña et al 2005(Sopeña et al , 2007. Fernandez-Urrusuno et al (2000) have developed the microspheres of alachlor by the solvent evaporation technique using ethyl cellulose as pre-existing polymer.…”