ABSTRACT In tropical and subtropical agricultural no-till (NT), lime and nitrogen (N) fertilizers are surface-applied. The pH increase from liming can enhance ammonia (NH 3 ) volatilization. This study aimed to quantify NH 3 losses from NT areas treated with different N fertilizers and lime rates and assess the effects on topsoil pH. Field experiments were conducted on clayey soil (Latossolo Vermelho distroférrico típico). The experimental design was a randomized complete block design with a 4 × 4 factorial split-plot arrangement and four replications. Main plots received four rates of dolomitic limestone (0, 2.6, 5.4, and 8.1 Mg ha -1 ) and subplots received four N fertilizers. Nitrogen fertilizers were: conventional urea (46 % N), urea coated with copper (Cu) and boron (B) (Ur-Cu+B; 0.15 % Cu, 0.4 % B, and 44 % N), NBPT-treated urea (Ur-NBPT, 46 % N and 0.53 % NBPT), and ammonium sulfate (AMS, 21 % N and 22 % sulfur). Nitrogen fertilizers were applied during two second-crop corn growing seasons, at 24 and 36 months after liming. Soil pH in the 0.00-0.05 m layer was determined at the end of the experiment. The increase in soil pH due to liming enhanced NH 3 -N volatilization losses, regardless of the N fertilizer used. Ammonia volatilization losses ranged from 16 to 32 % in urea plots, 12 to 31 % in Ur-Cu+B plots, 7 to 19 % in Ur-NBPT plots, and 0.2 to 5 % in AMS plots treated with lime rates of 0 to 8.1 Mg ha -1 , respectively. For every 1 Mg ha -1 of applied lime, NH 3 -N volatilization increased by 1.7 to 2.2 % in Ur plots, 1.6 to 5.1 % in Ur-Cu+B plots, 1.3 to 1.5 % in Ur-NBPT plots, and 0.7 to 0.9 % in AMS plots. These results highlight the need to adjust N management after liming, with ammonium-based fertilizers (e.g., AMS) or stabilized urea sources (e.g., Ur-NBPT) being more effective mitigation strategies than urea or Ur-Cu+B in reducing NH 3 volatilization under surface-limed no-till conditions.
Minato et al. (Thu,) studied this question.