Saturday, March 21, 2009

Turf and Landscape - Slow Release Fertilizers: Thermoplastic Resin Coated Fertilizer

This is the fourth in a series on slow release fertilizers for turf and landscapes. This post contains information on another coated slow release fertilizer product using thermoplastic resins.

Meister products are produced by using thermoplastic resins, such as polyolefins, polyvinylidene chloride, and copolymers as coating materials. The coatings are dissolved in fast-drying chlorinated hydrocarbon solvents and are applied to a variety of substrates including urea, diammonium phosphate, potassium sulfate, potassium chloride, and ammonium nitrate. Because the thermoplastic polymers used are highly impermeable in water, release controlling agents such as ethylene-vinyl acetate and surfactants are added to the coating to obtain the desired diffusion characteristics. Coating thicknesses are essentially the same for all products with the release pattern being controlled by the level of release-controlling agent. Release rates can also be altered by blending talc resin into the coating.

As with other polymer-coated fertilizers, nutrients are released by diffusion through the coating. The various releasing agents incorporated into the coating change the permeability characteristics, while the amount of release agent contained in the coating determines how fast the nutrients will diffuse. As with most polymer-coated fertilizers, the release is largely controlled by temperature.

Reprinted from Selected Fertilizers Used in Turfgrass Fertilization by J. B. Sartain and J. K. Kruse, University of Florida Extension.

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