Soil Basal Respiration as a Method to Determine The Influence of Soil Management and Microbial Activity

Soil respiration represents the transfer of CO₂ from the soil to the atmosphere and is one of the largest terrestrial carbon fluxes after gross primary production. Because it is driven largely by the metabolic activity of soil organisms, it is widely recognized as a sensitive indicator of soil biological activity, carbon turnover, and the impacts of environmental or management-related disturbances. Soil respiration integrates multiple CO₂ sources, including autotrophic respiration from plant roots and rhizosphere microorganisms, and heterotrophic respiration associated with microbial decomposition of organic matter. When measured in the absence of external substrates or recent nutrient inputs, microbial respiration is referred to as soil basal respiration (SBR). This article presents an infrared gas analyzer (IRGA) based protocol to quantify SBR under controlled laboratory conditions. To isolate the heterotrophic component attributable to microbial metabolism alone, plant-derived CO₂ fluxes are excluded by using preconditioned, sieved, and homogenized soil samples incubated under standardized moisture and temperature conditions, allowing quantification of cumulative C-CO₂ evolution over time, providing a robust proxy for microbial biomass, activity, and soil health. The protocol includes soil preparation, moisture adjustment, sealed-vial incubation, IRGA-based CO₂ measurement, and calculation of cumulative respiration. In this study, we assessed SBR using an infrared gas analyser (IRGA), which allows monitoring of soil CO₂ dynamics under controlled conditions. Representative results showed that compost addition enhanced microbial respiration in arid soils from the Tabernas Desert, indicating a strong stimulation of microbial processes following organic amendment. These findings highlight the usefulness of SBR as an indicator of soil management effects on microbial activity, particularly in degraded arid environments. Methodologically, the IRGA-based protocol offers a practical tool for research and teaching applications related to soil carbon dynamics.