Is Chelated Zinc Applied in-Furrow in a Liquid Starter Fertilizer Program Needed for Corn Production?.

Zinc (Zn) is the only essential micronutrient recommended in fertilizer program for corn (Zea mays L.) production in Minnesota. Zinc is recommended in Minnesota when soil soils test <0.75 mg Zn kg-1 (0-15 cm soil sample extracted by DTPA). Some farmers opt for applying Zn directly on the seed with their starter fertilizer regardless of soil test values. Our objective was to determine if the use of EDTA chelated Zn applied in-furrow enhance corn yield and whether the addition of EDDHA would enhance uptake of Zn for corn. Research was conducted at ten locations over five years. All treatments were applied as a liquid with the planter directly on the corn seed. Treatments were a control, 23-46 L ha-1 in-furrow starter fertilizer (11-15-0 N-P-K), 2.3 L ha-1 of a 10% EDTA chelated Zn, and a combination of in-furrow starter and chelated Zn. Most locations tested high in Zn (>0.75 mg Zn kg-1). The use of starter fertilizer increased early plant growth and nutrient uptake and sometimes increased corn grain yield. The use of EDTA chelated Zn did not increase early plant growth and did not increase corn grain yield. The results suggest that the use of chelated Zn is not needed when soil already test high in Zn. Targeting low testing field areas is still the best option to ensure profitability when applying Zn.