Effects of microbial inoculants on soil carbon stock, enzymatic activity, and above ground and belowground biomass in marginal lands of Northern India

Restoration practices in marginal lands for food production are the most important sustainability challenge for humans at the global level. Nature-based solutions (NBS) are among the best interventions to improve soil health, which directly enhances the soil productivity and biodiversity for improved sustainability of ecosystems. Our field experiment was conducted to evaluate the effects of three inoculants, two of which were bacterial: Azotobacter chroococcum (T1), Acetobacter diazotrophicus (T2), and the third fungal: Aspergillus awamori (T3) on soil properties, plant biomass, enzymatic activities (phosphatase, dehydrogenase activity), and soil carbon stock in marginal lands. The experimental results clearly revealed that the inoculations significantly enhanced plant growth and biomass (p < 0.01). The soil enzyme (dehydrogenase and phosphatase) activities increased under T3 and T2 treatments in response to inoculation. Interestingly, the significant results were observed in T3 and T1 treatment in the 4th year of observation for soil carbon stock (53.06 Mg ha(-1) yr(-1) and 51.41 Mg ha(-1) yr(-1), respectively). The total soil carbon stock was found to be 38.60 Mg ha(-1) yr(-1) in control plots. The inoculation enhanced (p <= 0.05) the soil biological properties like microbial biomass carbon as 267.62 +/- 18.73 mu gg(-1) to 894.24 +/- 41.65 mu g g(-1). We conclude that selected inoculations in marginal lands can provide a suitable option for eco-restoration and can sequester more atmospheric CO2 in to stable carbon pools to achieve UN Sustainable Development Goals and food security.