Abstract
Elevated ozone threatens the sustainability of soil ecosystems by negatively affecting underground ecological processes. Crop residue, as an energy source with a low risk of environmental influence, can alleviate the negative impacts caused by climate change. However, little knowledge is comprehended about the influences of crop residue input on soil nematode metabolic activities and microfood-web under elevated ozone. Soil microfood-web consisting of microorganisms and nematodes plays a significant role in the underground processes such as energy flow and nutrient turnover. Thus, the objectives of this study were to explore the responses of soil nematode metabolic activities and microfood-web to different elevated ozone levels and crop residue application managements. The pot experiment was a split-plot design with elevated ozone system as main plot and residue addition treatment as subplot utilizing the open-top chambers. Elevated ozone systems included three levels (control, 45 ± 5 ppb; lower elevated ozone level, 80 ± 10 ppb and higher elevated ozone level, 110 ± 10 ppb). Residue addition treatments were soil without residue addition and soil with residue addition. The results showed that elevated ozone generated negative influences on soil microorganisms and nematodes by decreasing their biomass carbon. Crop residue input practice increased the functional metabolic footprints of nematodes under elevated ozone. The carbon utilization of soil biological communities shifted from soil organic carbon to extractable organic carbon after crop residue incorporation. Soil nitrate-nitrogen was the main supplier to meet the nitrogen demand of soil biota. The analysis of structural equation modeling revealed that the system under elevated ozone without crop residue addition was predominated by a bacterial decomposition channel. While the application of crop residue into soils also made a contribution to the fungal decomposition pathway. Consequently, it can be concluded that organic input practice strengthens the cooperation of soil microfood-web channels, which plays an important role in alleviating the negative effects of elevated ozone on the stability of soil microfood-web.
•Elevated O3 decreased the biomass carbon of soil microorganisms and nematodes.•Crop residue application drove soil nematode metabolic activity under elevated O3.•Organic input shaped the fungal channel to alleviate O3 damage on microfood-web.