1. Impacts of Elevated Atmospheric CO 2 and N Fertilization on N 2 O Emissions and Dynamics of Associated Soil Labile C Components and Mineral N in a Maize Field in the North China Plain.
- Author
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Ma, Fen, Li, Ming, Wei, Na, Dong, Libing, Zhang, Xinyue, Han, Xue, Li, Kuo, and Guo, Liping
- Subjects
ATMOSPHERIC carbon dioxide ,SOIL dynamics ,EXTRACELLULAR enzymes ,CORN ,SOIL enzymology - Abstract
The elevated atmospheric CO
2 concentration (eCO2 ) is expected to increase the labile C input to the soil, which may stimulate microbial activity and soil N2 O emissions derived from nitrification and denitrification. However, few studies studied the effect of eCO2 on N2 O emissions from maize field under the free-air CO2 enrichment (FACE) conditions in the warm temperate zone. Here, we report a study conducted during the 12th summer maize season under long-term eCO2 , aiming to investigate the effect of eCO2 on N2 O emissions. Moreover, we tested zero and conventional N fertilization treatments, with maize being grown under either eCO2 or ambient CO2 (aCO2 ). We hypothesized that N2 O emissions would be increased under eCO2 due to changes in soil labile C and mineral N derived from C-deposition, and that the increase would be larger when eCO2 was combined with conventional N fertilization. We also measured the activities of some soil extracellular enzymes, which could reflect soil C status. The results showed that, under eCO2 , seasonal N2 O and CO2 emissions increased by 12.4–15.6% (p < 0.1) and 13.8–18.5% (p < 0.05), respectively. N fertilization significantly increased the seasonal emissions of N2 O and CO2 by 33.1–36.9% and 17.1–21.8%, respectively. Furthermore, the combination of eCO2 and N fertilization increased the intensity of soil N2 O and CO2 emissions. The marginal significant increase in N2 O emissions under eCO2 was mostly due to the lower soil water regime after fertilization in the study year. Dissolved organic C (DOC) and microbial biomass C (MBC) concentration showed a significant increase at most major stages, particularly at the tasseling stage during the summer maize growth period under eCO2 . In contrast, soil mineral N showed a significant decrease under eCO2 particularly in the rhizospheric soils. The activities of C-related soil extracellular enzymes were significantly higher under eCO2 , particularly at the tasseling stage, which coincided with concurrent increased DOC and MBC under eCO2 . We conclude that eCO2 increases N2 O emissions, and causes a higher increase when combined with N fertilization, but the increase extent of N2 O emissions was influenced by environmental factors, especially by soil water, to a great extent. We highlighted the urgent need to monitor long-term N2 O emissions and N2 O production pathways in various hydrothermal regimes under eCO2 . [ABSTRACT FROM AUTHOR]- Published
- 2022
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