Subsurface banding increases ammonia emissions under rainfed cotton in Florida sandy soils

Ammonia (NH 3 ) volatilization is a significant pathway for nitrogen (N) loss. The acidic, sandy soils of Florida offer ideal conditions for NH 3 losses in rainfed cotton production systems. To assess NH 3 losses under various N placement methods and rates, the experiment was conducted in 2023 and 2024 using a randomized complete block design with four replications. The study employed two placement methods: surface broadcasting and subsurface banding, and two N rates: 67.5 and 102 kg N/ha. Ammonia emissions were measured using open-chamber traps, with sampling conducted multiple times per week. Daily NH 3 emissions (g/ha/day) were averaged over each week, and cumulative emissions (g/ha) were calculated by summing weekly averages across the sampling period. These cumulative values were then used to estimate total NH 3 -N losses, expressed as a percentage of the total N applied. Sampling weeks were referenced as WAF (weeks after fertilization) to standardize timing across both years. Results indicated that both daily and cumulative NH 3 ; emissions were significantly higher with subsurface banding compared to surface broadcasting, leading to greater N-NH 3 ; losses under banding. In addition, neither placement method nor N rate significantly influenced cotton lint yield. These findings suggest that, under the conditions of this study, subsurface banding increased NH 3 volatilization losses in rainfed cotton grown on sandy soils in Florida.