title: Photostabilization of the herbicide norflurazon microencapsulated with ethylcellulose in the soil-water system.
abstract: Ethylcellulose-microencapsulated formulations (ECFs) of norflurazon have been shown to reduce leaching, maintaining a threshold concentration in the topsoil than the commercial formulation (CF). Since photodegradation contributes to field dissipation of norflurazon, the objective of the present work was to study if such formulations can also protect from its photodescomposition. For this purpose, aqueous solutions of CF and ECFs, containing the most important soil components (goethite, humic and fulvic acids and montmorillonite) were tested. To get a more realistic approach, studies in soil were also performed. The results were well explained by a simple first order model. DT(50) value was 3h for CF under irradiation, which was considerably lower than those corresponding to the systems where ECF was used (35 h for ECF; 260 h for ECF-goethite; 53 h for ECF-humic acids; 33 h for ECF-montmorillonite; and 28 h for ECF-fulvic acids). ECF protected against photodegradation in both aqueous solution and soil due to the gradual release of the herbicide, which reduced the herbicide available to be photodegraded. These lab-scale findings proved that ECF could reduce the herbicide dosage, minimizing its photolysis, which would be especially advantageous during the first hours after foliar and soil application.
authors.affiliation: Institute of Natural Resources and Agrobiology (CSIC), Reina Mercedes 10, Apdo 1052, 41080 Seville, ES, Spain. fsopenav@irnase.csic.es
authors.forename: Fatima
authors.initials: F
authors.lastname: Sopeña
authors.forename: Jaime
authors.initials: J
authors.lastname: Villaverde
authors.forename: Celia
authors.initials: C
authors.lastname: Maqueda
authors.forename: Esmeralda
authors.initials: E
authors.lastname: Morillo
mesh_terms: D002482:Cellulose / Q000031:analogs & derivatives* / Q000737:chemistry; D004339:Drug Compounding; D006540:Herbicides / Q000737:chemistry*; D010777:Photochemistry; D011724:Pyridazines / Q000737:chemistry*; D012989:Soil Pollutants / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D006540:Herbicides; D011724:Pyridazines; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; C013517:ethyl cellulose; D002482:Cellulose; C008677:norflurazone