Corn Response to Starter Fertilizer Acidity and Manganese Materials Varying in Water Solubility1

Abstract

AbstractManganese deficiencies occur on sandy Atlantic Coastal Plain soils that have been limed excessively. Granular Mn materials can be blended with starter fertilizer to overcome these deficiencies but variation in their water solubility and in starter fertilizer acidity affects the availability of Mn from these materials. Seven Mn materials varying in water solubility and three starter fertilizers were band‐applied to supply 11 kg ha−1of Mn to corn (Zea maysL.) on a sandy soil (fine‐loamy, siliceous, thermic Aquic Paleudult) at pH 6.9. Starter fertilizers, in order of increasing acid‐forming potential [NaNO3+ triple superphosphate (SNT); diammonium phosphate (DAP); and (NH4),SO4+ triple superphosphate (AST)] were applied at rates that supplied 28 and 31 kg ha−1of N and P, respectively, at planting. Soils were sampled through the fertilizer band at 30 days, whole plants were sampled at 30, 60, and 90 days, and leaves opposite and below the ear were collected at silking (75 days). Soil Mn, whole plant Mn concentration and uptake, and leaf Mn concentration increased with increasing solubility of the Mn materials. The MnO in the Mn materials did not contribute to these relationships. Increased acidity of the starter fertilizer also increased plant Mn concentration and uptake. Manganese deficiency symptoms occurred with the least acid‐forming starter fertilizer (SNT) and decreased with increasing water solubility of the accompanying Mn materials. Equations were developed to predict recommended rates of Mn material, depending on water solubility, to apply with each starter fertilizer