Anticipated rise in atmospheric carbon dioxide concentration and decreasing water availability for rice production are expected to alter rice productivity and environmental quality. We designed a field experiment under open top chambers (OTCs) to examine the influence of elevated CO2 (ECO2) and different water regimes on N mineralization and nitrous oxide (N2O) emission from rice soil. Experimental data revealed that labile N fractions such as microbial biomass-N increased by 31% whereas NH4+ and NO3- concentration decreased by 41 and 33%, respectively under ECO2 over ambient CO2 (ACO2). Rhizospheric denitrifier population was 35% higher whereas, nitrifier population decreased by 38% under ECO2 as compared to ACO2 in well-watered condition. Decrease in denitrifier population under WDS condition for ACO2 and ECO2 was 26 and 18%, respectively as compared to well-watered condition, whereas the decrease in nitrifier population was 29 and 38%, respectively. The ECO2 increased N2O emission and decreased mineralization rate of N in rice soil. Increased N2O emission under ECO2 was due to increased denitrifier and decreased nitrifier population and enhanced activities of extracellular enzymes. This information is of potential value towards identifying precise N management practices for ensuring higher N use efficiency under future drier and high CO2 conditions
Keywords: Elevated CO2, Nitrous oxide emission, labile nitrogen pool, Nitrogen mineralization, Water deficit stress
Note:
This abstract was presented/submitted at the International Conference on Agriculture (Agri Vision-2020) at Bhubaneswar, Odisha, india, during Jan 27-28, 2020.
