Corn gluten meal applicator for weed control in organic vegetable production

Producers of organic vegetables often report that weeds are their most troublesome production problem. Corn gluten meal (CGM), a by-product of the wet-milling process of corn, is phytotoxic. As a preemergence or preplant-incorporated herbicide, CGM inhibits root development, decreases shoot length, and reduces plant survival of weed or crop seedlings. The development of a mechanized application method forCGMand the ability to apply the material in a banded pattern would increase its use in organic vegetable production, especially in direct-seeded vegetables. The objective was to develop a mechanized method to uniformly apply CGM to the soil surface in either a solid (broadcast) or banded pattern. An applicator was assembled using various machinery components (fertilizer box, rotating agitator blades, 12-volt motor, and fan-shaped, gravity-fed, row-banding applicators). The equipment was evaluated for the application of two CGM formulations (powdered and granulated), three application rates (250, 500, and 750 g/m2), and two application configurations (solid and banded). Field evaluations were conducted during the summer of 2004 on 81 cm wide raised beds at Lane, OK. Differences between CGM formulations affected flow rate within, and between, application configurations. The granulated formulation flowed at a faster rate, without clumping, compared with the powdered formulation, while the CGM in the banded configuration flowed faster than the solid application. The delivery of CGM powder with the solid application configuration was inconsistent and unreliable, and therefore this material is considered impracticable when used in this configuration without further modifications to the equipment. The feasibility of using equipment, rather than manual applications, to apply CGM to raised beds for organic weed control purposes was demonstrated. Equipment alterations will increase the efficiency and potential usefulness of this equipment. If future research determines that the weed control efficacy between the two CGM formulations is equivalent, the granulated formulation would be the preferred one for use in this application equipment because it flows more smoothly. This equipment would be useful for evaluating benefits of banded applications of CGM for weed control efficacy and crop safety for direct-seeded vegetables.