Mitigating N2O emission from arable soils
by Haitao Wang
Date of Examination:2019-05-02
Date of issue:2021-04-23
Advisor:Prof. Dr. Klaus Dittert
Referee:Prof. Dr. Klaus Dittert
Referee:Prof. Dr. Petr Karlovsky
Referee:Prof. Dr. Michaela Dippold
Persistent Address:
http://dx.doi.org/10.53846/goediss-8564
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Abstract
English
Nitrous oxide (N2O) is an important greenhouse gas which contributes to climate change and ozone depletion. Mineral N fertilizers are one of the most important sources of N2O emission in agricultural systems. Enhanced-efficiency fertilizers (e.g., N fertilizers with added urease and nitrification inhibitors) represent possible approaches to N2O emission reduction and improved efficiency of N use. However, their adoption has been limited by the uncertainty of their effectiveness across different ecosystems. The present study aims to evaluate the effectiveness of several inhibitors under various environmental conditions. We found some of them showed their ability to reduce N2O emissions, for example Piadin and NBPT under laboratory conditions, while some of them are inefficient (NZONE MAX), and some exhibit inconsistent mitigation in N2O emissions (for example DMPP and NBPT under the wheat- wheat- oilseed rape rotation system). Although the nitrification inhibitor Piadin reduced N2O emissions from soil, it also increased the risk of higher NH3 volatilization. Our results reveal the complexity of soil microbial activity in relation to nitrification and denitrification, and provide some references to improve the efficiency of urease and nitrification inhibitors. These inconsistencies in effectiveness highlights the gap between laboratory and field conditions. One of the most important differences is that incubation experiments do not usually include plants. Our third experiment included both unplanted and planted soils. The results confirm our hypothesis that the presence of Lolium perenne increases the activity of microorganisms (probably through the release of root exudates) and lowers N2O emission through intense competition for mineral N between plant and soil microorganisms. However, further scientific questions have arisen from the results which require investigation. For example: how do root exudates regulate denitrifying communities, are root exudates stimulating or inhibiting nitrification and denitrification; how do plant species (e. g. leguminous and non-leguminous) affect the microbial communities; and how does the application of urease and nitrification inhibitors root exudates? In recent projects, researchers have discovered several compounds released from plant root exudates which have significant nitrification inhibition capacity. These biological nitrification inhibitors may provide an effective method of increasing the efficiency of N use and reducing N2O emission in future agricultural systems.
Keywords: Nitrous oxide; Arable land; Nitrification inhibitor; Lolium perenne