Effects of elevated ozone on the contribution of nitrogen rhizodeposition by spring wheat to different soil N pools
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Background and aims
Elevated ozone (O3) decreases nitrogen derived from rhizodeposition (NdfR). However, the changes in the partitioning of NdfR in soil N pools due to O3 remain unclear. The aims of this study were to investigate the contribution of NdfR to different soil N pools and its response to elevated O3 conditions.
Spring wheat was labeled with 15N–urea using a split-root technique under ambient (~40 ppb) and elevated O3 treatments (60 ± 5 ppb and 110 ± 5 ppb) in open-top chambers. Mineral-N, microbial biomass (MB)-N and fixed ammonium (FA)-N in rhizospheric soils were analyzed.
N rhizodeposition contributed 12–33% of mineral N, 10–14% of FA-N and 6–16% of MB-N under ambient O3. Elevated O3 significantly decreased mineral-15NdfR and increased FA-15NdfR but had no significant influence on MB-15NdfR. The decrease in mineral-NdfR was likely due to the decrease in rhizodeposition inputs and the increase in FA-NdfR.
Our results showed that elevated O3 altered the contribution of NdfR to soil N pools. The present study increases our understanding of the dynamics of NdfR and the changes in soil N cycling induced by projected future O3 levels.
KeywordsOzone N rhizodeposition Split-root technique 15N labeling N cycling Wheat
Nitrogen derived from rhizodeposition
Microbial biomass nitrogen
Fixed ammonium nitrogen
Lower ozone concentration-elevated level
Higher ozone concentration-elevated level
Roots sampled from the transfer compartment
Soil in the transfer compartment
- DAF15, DAF30 and DAF45
15, 30 and 45 days after ozone fumigation
This work was supported by the National Natural Science Foundation of China (grant number 41730855; 41703005; 41671290) and the National Key Research and Development Program of China (grant number 2016YFD0800103). We appreciate the anonymous reviewers for insightful comments on an earlier version of our manuscript.
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