Ammonia volatilization and yield of corn fertilized with different nitrogen sources in the Brazilian semiarid

Abstract

The objective of this work was to evaluate the effect of the use of different nitrogen fertilizers on N losses by NH₃ volatilization and on the grain yield of a corn (Zea mays) crop grown in the semiarid region of the state of Sergipe, Brazil. Corn was managed under rainfed conditions and conventional tillage. The fertilization treatments were: sulfur-coated urea (SU) and organo-mineral-coated urea (OMU). Regular urea and ammonium sulfate (AS) were also included as a reference of N sources of high and low NH₃-volatilization potential, as well as a control without N fertilization. The N sources were applied to the soil surface at a rate of 150 kg ha^-1 N as side-dressing at the V5 growth stage of corn. The experiment was carried out in 2015 and repeated in 2016. Losses of N through NH₃ volatilization differed among the N sources in the two study years, with AS presenting the lowest N losses and regular urea, the highest. In the area treated with OMU, losses by NH₃ volatilization were consistently controlled, showing a reduction of 74 and 67% in relation to that of regular urea in both years. SU, however, only mitigated NH₃-N losses in 2015, increasing them in 2016, compared with regular urea. Corn plant grain yield and N status, assessed by the index leaf, did not clearly reflect N losses by NH₃ volatilization. For the semiarid of Sergipe, OMU is the best urea-based fertilizer to mitigate N losses by NH₃ volatilization, and the use of AS is an alternative to increase corn yield and eliminate N losses as NH₃.