Addition of micronutrients to npk formulation and initial development of maize plants

Micronutrients are essential nutrients for plant growth and development; however, the micronutrient content in soil is often insufficient to ensure maximum productivity, which creates the need for their application through fertilizers. This study compared the availability of zinc, boron, manganese and copper to the soil, their absorption, accumulation and effect in developing maize plants, supplied as granules mixed with NPK granules or as powder, coating NPK granules. The experiment was conducted in a greenhouse, in a randomized block design with four replications, using a soil classified as Oxisol and maize hybrid AG1051. The formulation for fertilizers used was 4-30-10 (N- P2O5 -K2O) with 0.3% zinc, 0.1% boron, 0.2% manganese and 0.2% copper applied at doses of 0, 150, 300, 600, 1200 and 2400 kg ha-1, furthermore, doses of 4-30-10 without micronutrients were applied to ensure variation only for micronutrient doses. Coating NPK granules with micronutrients was better than the mixture for soil Zn content, zinc concentration and accumulation in the shoot and dry mass production. Both fertilizers presented similar behavior for soil B content, B concentration and accumulation in shoots. However, for the greatest dose, B results were better for the mixture of granules. The addition of Mn and Cu to NPK formulation resulted in no response in the soil, although the mixture resulted in greater concentration of Mn in the shoot and coating granules showed greater accumulation of Cu.