CONTROLLED-RELEASE FORMULATIONS OF ALACHLOR BASED ON CALCIUM ALGINATE

Granular controlled release formulations of alachlor were prepared fro m sodium alginate-kaolin-linseed oil-herbicide slurries dropped onto c alcium chloride to form spherical beads which were air-dried and evalu ated for release rates in a static water extraction. These formulation s gave considerably slower release of alachlor than a commercial formu lation and/or the alginate formulation without oil. Factors affecting the rate of release included aging of the dried formulation and the ra tio of oil/herbicide in the formulation. The size of the beads had no appreciable effect on the rate of release and several oils, including canola, corn, olive, safflower, peanut, soybean, and sunflower gave si milar release rates to linseed oil formulations for alachlor. The use of lignin in combination with alginate also produced a granular formul ation with reduced release rates.