Controlled release of isoproturon from an alginate-bentonite formulation: water release kinetics and soil mobility

• Published in: Pest management science 2000-09, Vol.56 (9), p.749-756
• Main Authors: Villafranca-Sánchez, M, González-Pradas, E, Fernández-Pérez, M, Martinez-López, F, Flores-Céspedes, F, Ureña-Amate, M D
• Format: Article
• Language: English
• Subjects: bentonite; Biological and medical sciences; Chemical control; controlled release; Fundamental and applied biological sciences. Psychology; isoproturon; leaching; Parasitic plants. Weeds; Phytopathology. Animal pests. Plant and forest protection; soil; sorption; Weeds
• ISSN: 1526-498X; 1526-4998
• DOI: 10.1002/1526-4998(200009)56:9<749::AID-PS196>3.0.CO;2-#

The herbicide isoproturon [3‐(4‐isopropylphenyl)‐1,1‐dimethylurea] was incorporated in alginate‐based granules to obtain controlled‐release (CR) properties. The basic formulation (sodium alginate (1.87%)–isoproturon (0.67%) in water) was modified by addition of different sorbents. The effect on isoproturon release rate, modified by the incorporation of natural and acid‐treated bentonite in alginate formulation, was studied by immersion of the granules in water while shaking. The release of isoproturon was diffusion‐controlled. The time taken for 50% of the active ingredient to be released into water, T50, was longer for those formulations containing added bentonite (5.98 and 7.43 days, for natural and acid‐treated (1 M H2SO4) bentonite, respectively) than for the preparation without bentonite (3.78 days). The mobilities of non‐formulated technical grade (98%) and formulated isoproturon were compared using soil columns. The use of alginate‐based CR formulations containing bentonite reduced isoproturon movement compared with the technical product. Sorption capacity of the soil for isoproturon was measured using batch experiments (0.29 litre kg−1) and the results obtained here in agreement with those obtained under dynamic conditions. © 2000 Society of Chemical Industry