A Gas Diffusion Analysis Method for Simulating Surface Nitrous Oxide Emissions in Soil Gas Concentrations Measurement

Abstract

The detection of low gas concentrations from the soil surface demands expensive high-precision devices to estimate nitrous oxide (N2O) flux. As the prevalence of N2O concentration in the soil atmosphere is higher than its surface, the present study aimed to simulate N2O surface flux (CF) from soil gas measured in a soil-interred silicone diffusion cell using a low-cost device. The methodological steps included the determination of the diffusion coefficient of silicone membrane (Dslcn), the measurement of the temporal variations in the N2O gas in the soil (Csi) and on the surface (MF), and the development of a simulation process for predicting CF. Two experiments varying the procedure and periods of soil moisture saturation in each fertilized soil sample were conducted to detect Csi and MF. Using Dslcn and Csi, the variations in the soil gas (Csoil) were predicted by solving the diffusion equation using the implicit finite difference analysis method. Similarly, using six soil gas diffusivity models, the CF values were simulated from Csoil. For both experiments, statistical tests confirmed the good agreement of CF with MF for soil gas diffusivity models 4 and 5. We suggest that the tested simulation method is appropriate for predicting N2O surface emissions.