Post-Harvest Resilience of Microbial Activity in Bacterially Inoculated Soils Under Drought Stress

Özet

The effects of microbial inoculation strategies on plant development in agricultural ecosystems are widely known. However, the "legacy effects" left on the soil after the main crop is harvested are not fully known. This study was conducted to examine the permanent effects of different Bradyrhizobium japonicum inoculation methods (seed and soil) on microbial stability during the 10-day plant-free incubation period after soybean (Glycine max L.) harvest in soils with a history of drought stress. In the study, soil respiration (CO₂), dehydrogenase activity (DHA), microbial biomass carbon (MBC) and metabolic (qCO₂) and specific (qD) ecophysiological indices were evaluated with multivariate statistical analyzes (PCA and Correlation). The findings showed that the "nutrient shock" caused by the cessation of post-harvest root exudates led to severe metabolic stress and carbon wastage from cellular respiration in the uninoculated control group. While drought stress (WS) suppressed microbial biomass and enzyme activities, inoculation from soil under stress (WS+A2) compensated for these losses in an extraordinary way. While basal respiration (CO₂) decreased dramatically by approximately 40% in WS+A2 application in the post-harvest period; The increase in microbial biomass (MBC) and enzyme activity (DHA) by 119.4% and 91.3%, respectively, compared to the stress group, proved that the microbial community maintained its cellular potential by reducing unnecessary carbon expenditure. As a result, it has been determined that bacterial inoculation from the soil goes beyond the existence of the plant and creates a high ecological resistance (resilience) in the soil microbiota against post-harvest hunger and drought shocks and prepares the ecosystem for the next production season by preserving carbon with maximum efficiency.