Coffee yield is influenced by soil properties, not by nitrogen fertilization strategies, under greenhouse gas monitoring in a Costa Rican Andisol

In recent years, Costa Rican coffee farms have increased nitrogen (N) inputs to maximize yields, using different rates, timings, and sources. N is often applied in complete fertilizers that include phosphorus (P), a limiting nutrient in Andisols due to their physical and chemical properties. However, excessive N use raises concerns about greenhouse gas (GHG) emissions and soil acidification. In 2024, a field trial was conducted for eight months at the Alsacia Coffee Farm (Starbucks Company) in Alajuela, Costa Rica, to evaluate coffee yield and quantify nitrous oxide (N 2 O) and methane (CH 4 ) emissions under three N fertilization strategies, considering soil interactions. The experiment used 15 × 16 m plots in six randomized complete blocks across two sectors (A and B) with contrasting microtopography. Treatments included: urea (U; 414 kg N ha - ¹, split into two applications), urea + urease inhibitor NBPT (F; 346 kg N ha - ¹), and ammonium nitrate (Y; 346 kg N ha - ¹), the last two split into three applications. No significant yield differences were observed during one crop cycle among treatments; however, yield was strongly affected by soil properties. Sector A, with 50% more clay and higher P, doubled the yield compared to Sector B. N 2 O cumulative emissions were similar for F and Y but higher in U due to greater N input. Soils acted as a CH 4 sink. Although treatment F had lower yield-scaled emissions (74 ± 20 g CO 2 e kg coffee - ¹ ) than U (146 ± 47 g CO 2 e kg coffee - ¹ ), the environmental impact was limited. Results highlight the importance of site-specific nutrient and soil management to improve sustainability in coffee production. Under the experimental conditions, soil texture and phosphorus content were key factors influencing coffee productivity.