Micronutrient supply through granular-coated single superphosphate under field conditions

ABSTRACT

The lack of efficient methods for soil-based micronutrient fertilization in field crops at sowing remains an important limiting factor for agricultural production in low fertility soils. Therefore, we evaluated the efficiency of single superphosphate (SSP) coated with either finely ground zinc (Zn) oxide or manganese (Mn) carbonate to supply Zn to corn (Zea mays L.), and Mn to soybean (Glycine max L.) and oat (Avena sativa L.) versus traditional sources (oxide and sulfate). One experiment for each micronutrient was performed under field conditions in two sequential growing cycles: rainy season (corn and soybean) and off-season (corn and oat). Treatments were combination of Zn or Mn fertilizers (oxide, sulfate, and SSP coated with Zn oxide or Mn carbonate) at rates of 1.25, 2.5, and 5.0 kg ha⁻¹ of Zn or Mn, plus a control. Micronutrient fertilization showed, relative to the unfertilized control, significant increases in shoot biomass at flowering, crop yield (corn silage and soybean grain), and leaf concentration and shoot uptake of Zn and Mn during the rainy season. Residual effect of Zn on off-season corn crop represented a 43% increase in grain yield over the control. However, oat did not respond to residual Mn. The positive effects of Zn and Mn application on crop performance did not depend on fertilizer material, suggesting similar fertilizer-use efficiency. We concluded that banded application of SSP coated with either finely ground Zn oxide or Mn carbonate would be a viable option to supply these micronutrients at the time of sowing in micronutrient-deficient soils.

KEYWORDS:

• Corn
• fertilizer material
• manganese
• nutrient uptake
• soybean
• zinc