Assessing the drivers of nitrogen fertilizer application in Panama to support sustainable nutrient management

Nitrogen fertilizers are vital for global food production, but their overuse can degrade ecosystems and compromise agricultural productivity. Although fertilizer use is increasing in Latin America, research on the drivers of nitrogen application remains limited, particularly at subnational scales where management decisions are made. Using the Republic of Panama as a model system, this study integrates census data, government records, Landsat imagery, and interviews with farmers to identify the factors shaping nitrogen application across districts. Nitrogen inputs varied widely among crops, with bananas and pineapples exhibiting the highest mean application rates at 278 and 189 kg ha^-1 yr^-1, while coffee, oranges, and pigeon pea received far lower amounts (<40 kg ha^-1 yr^-1). Agronomic factors were particularly influential, and both crop type and farm size emerged as significant predictors of nitrogen use. Notable, larger farms applied more nitrogen per hectare, as indicated by the positive elasticity of farm size where a 1 % increase in farm size corresponded to a 0.35 % increase in nitrogen application, likely reflecting greater resource availability and the use of more input-intensive production systems. In contrast, districts with greater adoption of conservation practices applied less nitrogen overall, underscoring the role of sustainable management in reducing fertilizer inputs. For example, model predictions indicate that increasing conservation adoption from 15 % to 25 % at the district level is associated with a 39 % reduction in nitrogen application. We also generated the first district-level nitrogen fertilizer application map for Panama, revealing substantial spatial variation ranging from 10.34 to 1032.60 kg ha^-1 yr^-1, with central and western districts showing the highest values. These findings underscore the complexity of fertilizer use across Panama and emphasize the need to consider farm structure, crop composition, and conservation practices when designing strategies for sustainable nutrient management, providing an essential baseline for future policy and decision making.