Foliar Micronutrients for Greater Corn Yield.

Under optimum growing conditions, adequate nutrient availability often limits corn (Zea mays) growth and productivity. Nitrogen, potassium, and boron accumulation mainly occurs before flowering compared to the uptake of phosphorus, sulfur, and zinc, which primarily occurs during grain-filling. Increased planting densities and hybrid selection create a high-yield potential in today’s modern corn production systems, necessitating greater nutrient supply or efficiency. Limited plant remobilization and translocation of Zn requires greater root accumulation of Zn in the absence of supplemental foliar nutrition. Alternatively, peak demand for B occurs immediately prior to pollination and is subsequently remobilized from leaf tissues to developing reproductive organs (ear and tassel) during the initiation of reproductive growth. Our objective was to quantify yield responses to foliar B and/or Zn nutrition when used in intensive corn production systems. The experiment was conducted in Champaign, IL in 2014 and 2015. A population tolerant corn hybrid was evaluated at planting densities of 79,000, 94,000 and 109,000 plants ha^-1. Treatment applications were designed to supply nutrients based on known patterns of nutrient accumulations and included a foliar boron application of 71.4 g ha^-1 using a chelated boron source at V16 and a foliar zinc application of 202.1 g ha^-1 using a chelated zinc source at R2. The yield increase associated these applications appeared to be greater with higher planting densities. There was a 128 kg ha^-1 yield increase at the moderate and high populations when foliar B was applied and a 215 to 397 kg ha^-1 yield increase at higher populations from foliar Zn applications. Greater planting populations tend to decrease individual plant root volume, and may limit the ability to accumulate nutrients even in soils with nutrient test levels that are considered ‘adequate’. In modern corn production, greater planting densities provide the opportunity for increased grain yield and as a result, optimum nutritional management that includes foliar nutrient applications also becomes more important.