Nitrogen Fertilization Reduces the Capacity of Soils to Take up Atmospheric Carbonyl Sulphide

Abstract

Soils are an important carbonyl sulphide (COS) sink. However, they can also act as sources of COS to the atmosphere. Here we demonstrate that variability in the soil COS sink and source strength is strongly linked to the available soil inorganic nitrogen (N) content across a diverse range of biomes in Europe. We revealed in controlled laboratory experiments that a one-off addition of ammonium nitrate systematically decreased the COS uptake rate whilst simultaneously increasing the COS production rate of soils from boreal and temperate sites in Europe. Furthermore, we found strong links between variations in the two gross COS fluxes, microbial biomass, and nitrate and ammonium contents, providing new insights into the mechanisms involved. Our findings provide evidence for how the soil–atmosphere exchange of COS is likely to vary spatially and temporally, a necessary step for constraining the role of soils and land use in the COS mass budget.

Seasonal dynamics of the COS and CO<sub>2</sub> exchange of a managed temperate grassland

“…Another factor contributing to the high COS soil emissions might be the yearly fertilization using slurry, as high nitrogen 378 content in soils has been linked to a higher source strength of COS (Kaisermann et al, 2018). This agrees well with the study 379 of Kitz et al (2019), who found a correlation between increased soil nitrogen content and soil COS emission in a laboratory 380 experiment with samples taken from the grassland at two different dates (i.e.…”

Soil COS Exchange: A Comparison of Three European Ecosystems

“…In the few experiments where COS emission were detected (Bunk et al, ; Whelan et al, ), the corresponding soil samples were very dry, as with the SAV samples (Figure ). Other soil parameters, found to influence the soil COS exchange in the literature, are soil pH (Sauze et al, ) and soil nitrogen content (Kaisermann, Jones, et al, ; Meredith et al, ). Soil pH differed between our samples (Figure ) with COS uptake in the more acidic samples and COS production in the less acidic samples, while no apparent pattern emerged from the C/N ratio of our samples with regard to soil COS fluxes (supporting information Figure S3).…”

“…The motivation to understand how soil COS fluxes vary with soil moisture, soil temperature, and radiation is therefore growing, since more knowledge is needed to adequately represent the soil COS exchange in models (Whelan et al, ). Advances have been made in understanding the impact of soil moisture on the soil COS flux by recent laboratory studies (Bunk et al, ; Kaisermann, Jones, et al, ), which investigated soil samples from different ecosystems, concluding that COS production increases under drier conditions. Bunk et al () showed that soil samples can act as both a net COS sink and source depending on their soil moisture.…”

Formation and Fluxes of Soil Trace Gases

“…For example, Meredith et al (2018) observed an exponential increase in OCS production in dry soils without a decline at high temperatures that would denature enzymes, suggesting the process is driven by zero-order chemical production and not biological production [5]. First-order trace gas consumption processes are sensitive to trace gas (substrate) concentrations, which Kaisermann et al (2018) leverage to partition OCS NSE by varying OCS concentrations to stimulate microbial consumption rates, while OCS production does not vary [6]. They derive gross consumption and production rates from this method and additionally use reactive trace gas models to account for physical factors of the soil system and derive underlying bulk enzymatic rates for OCS consumption.…”

“…An approach to reconciling this discrepancy must, then, be developed, such that the results of the laboratory study provides information that is meaningful and complementary to what can be achieved through field investigations. For example, Meredith et al (2018) and Kaisermann et al (2018) both utilized the benefits of a controlled laboratory environment and access to advanced analytical equipment to test specific hypotheses related to the spatial variability observed between different soil types and land uses for the soil production and uptake of OCS. Instead of focusing on obtaining the most environmentally realistic and directly scalable measurements of OCS production and uptake rates possible, these two studies aimed to elucidate factors (e.g., nitrogen fertilization/availability, soil carbon, and organic sulfur species) that were hypothesized as potential drivers behind variability in OCS fluxes in previous studies.…”