I2.2Flow of Agricultural Nitrogen

Abstract

The emission, atmospheric transport and deposition of ammonia (NH3) forms an important link between the terrestrial nitrogen cycle, atmospheric chemistry and agricultural productivity. This presentation discusses the FAN process model, which has been incorporated into both the E3SM land model (ELM) and the Community Land Model (CLM). FAN simulates atmospheric NH3 emission in agricultural activities such as fertilizer application and manure management, and includes sufficient mechanistic detail to simulate responses to both environmental and agricultural drivers. Comparison between global, multi-year FAN simulations and existing NH3 emission inventories shows that the simulated volatilization losses are compatible with the current estimates for North America and Europe and China but differ over the data sparse regions of Africa, Latin America and India. Coupling FAN with an atmospheric model allows us to evaluate the model through atmospheric measurements of ammonia and ammonium concentration and deposition. Using data from atmospheric monitoring networks, we show that FAN captures these measurements as well as regionally based inventories. This is a first step in simulating the coupled land-atmosphere nitrogen cycle through process-based modeling suitable for climate and N-cycle simulations.