Elevated CO2, O3 and their interaction have differential impact on soil microbial diversity and functions in wheat agroecosystems

Abstract

Elevated carbon dioxide (EC) and elevated ozone (EO) due to changing climate have a significant impact on the plant growth rate, primary productivity, and root turnover. EC and EO could have a differential impact on the structure and functioning of soil microbial communities in terrestrial ecosystems via modifications in the microbial population, soil enzyme activity, decomposition of organic compounds and cycling of nutrients. For the development of sustainable agroecosystems, soil microbial communities are essential due to their major roles in nutrient cycling, crop-microbe interplay and resistance towards biotic/abiotic factors. However, it remains difficult to project how multiple climate change factors would affect below-ground functions. Free-Air CO2 and O3 enrichment facility (FAOCE) was used to explore the effects of EC (550 ± 50 ppm) and EO (65 ± 10 ppb) along with their combined interactive treatment ECO on the structure and abundance of soil microbial community, microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) and microbes involved in N cycling in wheat crop (Triticum aestivum) under field conditions. The MBC increased by 20% in EC and declined by 5% in EO to ambient control. Treatments EC and ECO stimulated the growth of ammonia and nitrite-oxidizing bacteria. Heterotrophic microbial populations were favoured under EC and inhibited under EO. Treatments indirectly affected the soil microbial community structure by altering N-cycling microbes and modifying MBC and MBN which eventually changed soil fertility and biogeochemistry.