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    Granular Application Equipment—The State of the Art and Current Problems

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    This discussion focuses on granular application equipment purchased and used by the farmer. Often this equipment is part of a planter or seeder but may be separate or combined with other implements. Insecticide applicators are the most popular granular attachment on row crop planters, followed in order by fertilizer and herbicide attachments. Fertilizer is the most popular granule used with small grain seeders, but herbicide and insecticides are also occasionally applied. A granular applicator must meter, deliver, and distribute the chemical. In some cases, soil incorporation is also required. Granules are usually metered either through a gravity-fed metering orifice or through a positive metering device in which a constant granule volume is metered by means of a rotor. The granule is then delivered to a target location by means of gravity or pneumatic pressure. In some cases, such as with insecticides, several alternative distribution methods and sites must be provided. These include application in the seed furrow or a broadcast band over the row that either remains on the soil surface or is incorporated into the soil profile.

    Engineering decisions interact with physical and chemical properties of granular chemicals. Uniform metering is dependent upon careful control of factors such as particle size, bulk density, flowability, and caking susceptibility. Factors such as granule crushing strength, abrasiveness, and impact resistance affect the vigor with which mechanical systems can be designed to handle and deliver granules. The hygroscopic and corrosive properties of granules affect maintenance procedures and durability of a given application system. Future customers will demand and deserve improved granule application systems. Interdisciplinary cooperation can assist in targeting realistic areas to improve the ease, safety, and efficiency of chemical granule use.


    equipment usage, metering, granule physical properties, granule chemical properties, engineering concerns, pesticides

    Author Information:

    Johnson, RR
    Staff agronomist, Deere & Company Technical Center, Moline, Ill.

    Committee/Subcommittee: E35.22

    DOI: 10.1520/STP31790S