Soil microbes, carbon, nitrogen, and the carbon to nitrogen ratio indicate priming effects across terrestrial ecosystems

PurposeThe control of the exogenous carbon-induced soil-priming effect (PE) by soil microbes, carbon, nitrogen, and carbon/nitrogen is still uncertain. To examine the relationship between diverse soil properties and the PE, the research was conducted using soils from forest, cropland, and grassland ecosystems.MethodsWe introduced a solution of C-13-labeled glucose (containing 6 atom% C-13) into soils collected from three distinct ecosystems. For the control group, we added an equal amount of water to the soils. Subsequently, all treatment and control samples were incubated at 60% of their water holding capacity and maintained at a temperature of 25 & DEG;C for a period of 28 days.ResultsThe magnitude of priming on native SOC was significantly higher in grassland ecosystems than in forest and cropland ecosystems. The results of structural equation modelling revealed a significant positive association of the PE with the soil carbon/nitrogen ratio, bacterial diversity, and community composition, as well as a negative association of the PE with SOC, dissolved organic carbon, and total nitrogen. Network analysis showed that the keystone taxa for each ecosystem were different. Sphingomonas, SBR1031, BD2-11-terrestrial-group, and Sebacina were the keystone taxa significantly positively associated with the PE, whereas Solirubrobacter, Bacillus, and Preussia were the keystone taxa significantly negatively associated with the PE.ConclusionOur findings are significant for studying carbon fluxes, improving soil carbon dynamics models, and understanding soil microbe, carbon, and nitrogen relationships with SOC mineralization. This understanding is crucial for mitigating climate change, promoting sustainable land management, and enhancing soil carbon stabilization.