Application of soil amendments to enhance soil carbon and biological properties in a paddy field under elevated CO2 conditions

A field experiment was carried out to elucidate the effect of elevated carbon dioxide (eCO(2) - 550 +/- 30 ppm) on soil enzymes (dehydrogenase, beta-glucosidase, fluorescein diacetate, urease, acid and alkaline phosphatase), soil carbon pool (Soil Organic Carbon (SOC), Microbial Biomass Carbon (MBC), oxidizable carbon, humic acid (HA), fulvic acid (FA) fractions), microbial population dynamics (heterotrophs, fungi, actinobacteria, diazotrophs, methanotrophs, and total anaerobes), carbon sequestration and yield in a flooded paddy soil in open top chambers (OTCs) in relation to rhizospheric and bulk soil. Responses of most of the observed parameters to eCO(2) with biochar application in rhizosphere soil were significantly higher. The carbon (C) sequestration potential was found higher in the biochar applied plot under eCO(2) with 0.59 Mg C sequestered ha(-1). The same recorded the highest biomass yield and grain yield which is 12.8 and 30.8% higher than the control. Principal Component Analysis (PCA) recognized soil dehydrogenase, beta - glucosidase, SOC, FA, Substrate Induced Respiration (SIR), metabolic quotient (qCO(2)) and counts of heterotrophs as key drivers of variability. The current study thus provides some dependable biological indicators to assess the paddy ecosystems, vis-a-vis anticipatory climate change.

Automated summary

A field experiment was conducted to investigate the effects of elevated carbon dioxide on soil enzymes, soil carbon pool, microbial population dynamics, carbon sequestration, and yield in flooded paddy soil. The results showed that most of the observed parameters responded significantly higher in the rhizosphere soil with biochar application under elevated carbon dioxide levels. The study also identified key drivers of variability and provided reliable biological indicators for assessing paddy ecosystems in the face of anticipated climate change.