Dual Functional Coatings for Urea to Reduce Ammonia Volatilization and Improve Nutrients Use Efficiency in a Brazilian Corn Crop System

Abstract

The investigation aimed to evaluate the use of micronutrients Zn, B, and the urease inhibitor (N-(n-butyl) thiophosphoric triamide) (NBPT), associated with an organic polymer to reduce ammonia losses (N-NH3) and increase maize yield. Two experiments were conducted under field conditions in Luminarias and Ingai, Minas Gerais, Brazil. The treatments consisted of the application of prilled urea, urea coated by an organic polymer, polymer + zinc (Zn), and boron (B) or NBPT, which are urease inhibitors in the soil, and a control treatment without N application. The reduction of N-NH3 losses applying the studied sources ranged between 0.2 and 42% on average. Leaf N concentration at flowering varied between 21 and 27 g kg−1, Zn concentration varied between 34 and 38 mg kg−1, and grain yield ranged from 3403 to 4810 kg ha−1. Grain yield increased by 15% on average compared to the control treatment. The addition of the organic polymer alone to urea reduces N losses by volatilization compared to prilled urea. However, when associated with Zn and B additions, this approach becomes more effective. The NBPT (N-(n-butyl) thiophosphoric triamide) concentrations used in this study exhibited low efficiencies in reducing N losses by volatilization. The application of Zn and B with the organic polymer affected nutrient uptake at the maize flowering stage but was not enough to increase maize yield. The removal of Zn and B by the grains was enhanced by the addition of these micronutrients to the organic polymer coating, regardless of the Zn source.