Agricultural fields are complex systems that often exhibit spatially and temporally heterogeneous greenhouse gas emissions patterns. Methods using static gas flux chambers tend to capture the spatial variability but cannot provide high temporal resolution data because of the labour involved in deployment. In agricultural systems, where large event-driven (i.e. fertilization, precipitation) pulses of greenhouse gas emissions dominate the annual greenhouse gas budgets, the lack  of temporal resolution with static chamber approaches can severely affect the results.

Until recently, in-situ measurements of the primary greenhouse gases were not practical and discrete gas samples had to be taken back to the lab for analysis. Now, state-of-the-art laser-based systems that simultaneously measure CO₂, CH₄ and N₂O, are readily available opening up new avenues of research by providing real-time, high temporal resolution, and high accuracy. These laser-based systems have demonstrated comparable accuracy to traditional methods like GC, but with the additional benefit of substantially increasing the measurement frequency, thereby lowering the Minimum Detectable Flux limit that researchers can expect from their experiments.

Here, we use a field study at an experimental soil amendment (biosolids) study to show how the increased measurement frequency of the CRDS instruments can substantially alter the estimate of cumulative greenhouse gas flux at the site by taking into account short time scale, pulse-driven variation in greenhouse gas emissions. In addition to this, we will be coupling the Picarro G2508, 5-species analyzer, and the Picarro G5101-i to determine the N2O isotopomer flux following biosolids addition, using the N isotopomers to identify the mechanisms of N2O production in the soil. Finally, we will focus on demonstrating how the usage of these high-resolution instruments in the field allowed us to detect significantly smaller fluxes through calculation of the systems’ Minimum Detectable Flux and comparison to traditional techniques using static chambers and gas chromatography.