Nitrous oxide gas is a long-lived relatively active greenhouse gas (GHG) with an atmospheric lifetime of approximately 120 years, and heat trapping effects about 310 times more powerful than carbon dioxide per molecule basis. It contributes about 6% of observed global warming. Nitrous oxide is not only a potent GHG, but it also plays a significant role in the depletion of stratospheric ozone. This book describes the anthropogenic sources of N2O with major emphasis on agricultural activities. It summarizes an overview of global cycling of N and the role of nitrous oxide on global warming and ozone depletion, and then focus on major source, soil borne nitrous oxide emissions. The spatial-temporal variation of soil nitrous oxide fluxes and underlying biogeochemical processes are described, as well as approaches to quantify fluxes of N2O from soils. Mitigation strategies to reduce the emissions, especially from agricultural soils, and fertilizer nitrogen sources are described in detail in the latter part of the book.

Manure application to grassland and arable land is an important source of ammonia and nitrous oxide losses. For both gasses, national and international policies have been developed with the objective of reducing the emissions. Since the early 1990s, measurements have been carried out in The Netherlands to assess the gaseous losses from manure application, especially for ammonia. Measurements of nitrous oxide emissions are relatively scarce. This paper presents the results of these measurements with the objective of providing an updated quantification of the effect of techniques for application and incorporation of manure, and to assess influencing factors. The manure application techniques differ in their spreading or placement of the manure onto the grass or soil surface or into the soil. The following techniques are treated in this paper: surface spreading, narrow-band application, shallow injection with open slots on grassland, and surface spreading, surface incorporation, deep placement on arable land. Low emission techniques such as narrow band application, shallow injection, incorporation or injection on arable land show a significant reduction of ammonia emission compared to surface spreading. On grassland, average emission factors (% of total ammonium nitrogen) were 74% for surface spreading and 16% for shallow injection. On arable land, the emission factors were 69% for surface spreading and 2% for deep placement. However, the nitrous oxide emission factor from manure applied with low ammonia emissions techniques is higher than the emission factor for surface applied manures. In a whole farm context, the higher nitrous oxide emission with shallow injection is partly offset directly by reduced emissions from fertilizer savings and indirectly from lower ammonia losses.

The present work evaluated the effect of mineral nitrogen (N) fertilizer application during crop production on the potential risk of gaseous N loss in the form of nitrous oxide (N2O). Nitrous oxide (N2O) is an environmentally important atmospheric trace gas and contributes to the anthropogenic greenhouse effect. In addition, it is a precursor to photochemical nitric oxide (NO) production in the stratosphere which leads to stratospheric ozone depletion. Agriculture is considered to be the main source of anthropogenic N2O, with agricultural soils representing the single largest source due to nitrogen fertilizer applications during crop production. The purpose of this study was to examine the effects of mineral N fertilizers (N form, amount, mode of application) on N2O emissions from fertilized croplands in north-west Germany. Therefore several field trials, one greenhouse pot experiment and two incubation experiments were conducted. Nitrous oxide fluxes were measured by means of the closed chamber method. The length of the experimental period varied between experiments from several weeks (42 days) up to one-year measurement campaigns. The amount of N2O emitted during the crop growth period depended on the N form applied as well as on the mode of application, and a linear relationship between cumulative N2O emissions and total N fertilizer amount applied was found.