Irrigated Corn and Soybean Response to Starter and Foliar Fertilizer Applications.

Foliar fertilizers and inclusion of micronutrients with starter fertilizers are often used by producers under high-yield environments for corn and soybean. The objective of this study was to evaluate the effectiveness of starter and foliar fertilization including micronutrients. Field studies were conducted at four irrigated locations during 2010 and 2011. A factorial arrangement in a randomized complete block design was used where each main factor (starter and foliar) included a control, NPK, and NPK plus a micronutrient mix (B, Cu, Fe, Mn, and Zn), resulting in nine treatment combinations. Starter fertilizer was dribbled over the row at planting, and foliar fertilizer was sprayed at V6-V8 in corn and R1-R2 in soybeans. To identify likelihood of crop response, soil and tissue analyses were evaluated prior to treatment applications for each small plot. Some micronutrient tissue concentrations in corn and soybeans were significantly changed by the addition of the micronutrient starter fertilizer. The tissue concentrations of all nutrients of corn and soybean in each small plot were near or well above documented critical levels prior to foliar application, except for P in 2010 Scandia corn. At Scandia in 2010, starter fertilizer application increased corn tissue P concentration and early growth, though corn grain yield was not significantly increased over the control with any treatment combination. Likewise, no yield response was found with soybeans at Scandia in 2010. The 2010 Clay Center corn grain yield was not significantly different among any of the treatment combinations whereas soybean demonstrated a significant treatment interaction for grain yield. Additional sites years need to be assessed for yield response to micronutrient applications in high-yield environments.