Predicting changes in greenhouse gas emissions in muck soil using physical observations

Abstract

<abstract> <b>Abstract.</b> Greenhouse gas (GHG) fluxes in the field are temporally variable due to weather events, which may be predicted from ancillary soil measurements like soil moisture, soil water content and soil temperature. Hand-held probes provide point measurements in the field, but wireless sensor networks (WSN) are more useful for describing the dynamics of soil properties via in-situ probes, in relation to the temporal variations in GHG fluxes. WSN probes enable continuous measurements to be gathered from the field easily and at a relatively low cost. This is particularly important in soils that exhibit high temporal variability in GHG fluxes, such as organic (muck) soils. The objective of this study was to relate continuous soil water content and soil temperature measurements with the emissions of nitrous oxide (N₂O), methane (CH₄) and carbon dioxide (CO₂) throughout the growing season of irrigated onion production on muck soils. The GHG fluxes were calculated from regular sampling of static, non-steady state chambers and gas chromatography measurements. Soil water content and soil temperatures were measured using portable sensors in addition to a stationary WSN. Relatively cool and wet soil conditions resulted in greater N₂O fluxes whereas relatively dry and warm soil conditions were associated with more CO₂ release. With respect to sensor technologies, soil matrix potential sensors were better at predicting high GHG fluxes than capacitance moisture sensors. This research shows the potential of WSN to evaluate the relationship between GHG fluxes and the environmental conditions of muck soils, using real-time measurements of soil moisture and temperature conditions.