Nitrogen fertilizer technologies: Opportunities to improve nutrient use efficiency towards sustainable coffee production systems

Adequate fertilizer management is fundamental for efficient use of N and the sustainability of coffee crop environment. Thus, an experiment was conducted for four consecutive years with Coffea arabica L., seeking to assess strategies for nitrogen fertilization considering losses of N-NH3 and agronomic aspects of the coffee plant. The following fertilization technologies were used: ammonium nitrate -AN, conventional urea, and urea with N-(n-butyl) thiophosphoric triamide -NBPT (UNBPT source), applied in five doses (from 0.0 to 525 kg N ha-1 crop season-1). Quantification was made for NH3 losses, N content in the leaves and that exported in the fruit, and yield. The losses of NH3 at the dose of 150 kg N ha-1 were urea (13.7 %) > UNBPT (6.2 %) > AN (0.6 %); and at the dose of 400 kg N ha-1, urea (13.6 %) > UNBPT (9.5 %) > AN (0.3 %). N-NH3 losses from urea ranged from 5.3 % to 24.2 % of the N applied. The NBPT delayed 3.8 days (at the dose of 150) and 2 days (at the dose of 400) to maximum emission of N-NH3 in relation to urea. The AN and the UNBPT reduced volatilization in relation to urea by 96 % and 43 %, respectively. We present a pioneering study of long-time field trial with the main nitrogen fertilizers used on coffee crops, which carries scientific advances important for coffee growing.