Estimation of ammonia and nitrous oxide emissions from turfgrass systems using a dynamic chamber method and a biogeochemical modeling framework

Abstract:

Turfgrass management is characterized by intensive use of fertilizers, irrigation, and pesticides that contributes to reactive nitrogen emissions to the environment. This work aimed to estimate ammonia (NH₃) and nitrous oxide (N₂O) emissions from turfgrass systems by combining measurements from field experiments and simulations from a biogeochemical model. Field experiments were conducted seasonally by using a dynamic chamber method on a 50 ft by 50 ft tall fescue field at Lake Wheeler Turfgrass Field Laboratory, Raleigh, NC. Emission measurements indicate a wide range of emissions for NH₃ (3.5-117.5 ng NH₃-N m^-2 s^-1) and N₂O (7.2-24.3 ng N₂O-N m^-2 s^-1). Both NH₃ and N₂O emissions were higher during spring and summer, suggesting that the emissions are influenced by temperature-regulated soil processes (e.g., NH₃ volatilization and microbially-driven denitrification). Meanwhile, the biogeochemical modeling simulations were performed by using the Environmental Policy Integrated Climate (EPIC) model. The model utilized customized input files such as site information, daily weather data, soil physical and chemical characteristics, fertilizer types, and the site management options. The model performance was evaluated by comparing the simulation results with observational data from field experiments. Outputs from EPIC simulations were consistent with results from the field experiments (R = 0.5-0.8). However, EPIC constantly underestimated emissions measured during the field experiments. This highlights a more comprehensive data collection and analysis to improve the model performance for future works.