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Mitigation of nitrous oxide emissions from arable soils
On June 30th starting at 10:00 doctoral student Jordi Escuer Gatius will be defending his thesis „Mitigation of nitrous oxide emissions from arable soils."
The need to reduce emissions of greenhouse gases responsible for global warming of the planet is generally acknowledged. Agriculture is the main anthropogenic source of non-CO2 emissions, which include N2O and CH4. Anthropogenic emissions represent approximately half of the total global N2O emissions, and agriculture is responsible for around two-thirds of those emissions. This is especially important because N2O has a global warming potential 273 times that of CO2 and is currently the main stratospheric ozone-depleting substance.
The aim of this PhD thesis was to contribute to the understanding mechanisms behind N2O emissions and in the mitigation potential of N2O emissions of biochar and the nitrification inhibitor DMPP.
Field emissions were driven by organic fertilization and freeze-thaw events. Organic fertilization increased N2O emissions in all cases, but mineral fertilization did not immediate increase emissions. Fresh rapeseed and rye residues incorporation into the soil increased N2O emissions with similar emissions to those measured for organic fertilization, while wheat straw incorporation did not increase emissions. The studied mitigation tools did not reduce N2O emissions. Emissions coming from denitrification, due to the environmental and field conditions, resulted in ineffectiveness of the nitrification inhibitor, with differences in N2O emissions attributable to differences in soil water content. High temperature hay biochar application, on the other hand, increased N2O emissions, which is explained by the release of C and N from the applied biochar.
This research highlights the importance of the relationships between soil amendment properties and soil N2O emissions, and finally the moment of application. Research on mitigation tools should focus on developing effective farmer-oriented tools that consider amendment characteristics, soil properties and weather conditions.
Supervisors are associated professor Merrit Shanskiy, associated professor Kaido Soosaar (University of Tartu) and professor Alar Astover, opponent is prof. Dr. Klaus Butterbach-Bahl (Karlsruhe Institute of Technology). Abstract is available in Library of Estonian University of Life Sciences DSpace archive.