Ammonia emissions is an important topic in many countries with animal production, since it contributes to environmental and health problems. Strategies and measures to reduce ammonia emission are getting increasing attention in national and international legislation. This book aims to bring together visions and knowledge from scientists, policy makers and other relevant stakeholders around the subject of NH3 emissions from agricultural operations and its reduction options. It also offers a basis for international harmonization on various NH3 emission related topics (e.g. national emission inventories, measurement techniques and strategies, data on emissions and reductions) and, last but not least, it provides an update of science concerning NH3 and related environmental issues. The focus of this publication is on NH3 emissions from various agricultural sources (grazing, animal housing, manure storage, land application of manures), and the options for their reduction in a farm system approach. Also, multiple gaseous emissions, their reduction options and pollution swapping issues are addressed. Environmental impact and health related effects of NH3 are briefly addressed. In conclusion, this book gives an overview of the current knowledge about ammonia emissions and how we can implement this knowledge in current agricultural systems.