Enhanced ammonia volatilization prediction with EPIC: Model description and testing of different fertilizers

Biogeochemical models are promising cost-effective tools to evaluate ammonia (NH3) volatilization reduction strategies at large spatial scales provided they capture all the relevant processes that regulate universally the nitrogen (N) cycle in agroecosystems. This work aims to enhance the Environmental Policy Integrated Climate (EPIC) model to improve its ability to simulate NH3 volatilization from both organic and mineral N fertilizers in agricultural fields. Extant algorithms of NH3 volatilization in EPIC were replaced with a mechanistic submodel that, operating at hourly steps, effectively simulated NH3 volatilization by capturing processes of ammonium (NH4+) adsorption, urea hydrolysis, soil pH-based partitioning of total ammoniacal N into NH3 and NH4+, and mass transfer. The new EPIC submodel was calibrated and validated using data from two different locations (Legnaro, NE Italy; Eatonton, Georgia, USA), including several combinations of fertilizer types and application methods in...