Perspectives on Ammonia Abatement in Canada.

There is growing international concern about leakage of reactive N into the environment from human activity including farming. In Canada the greatest reactive N loss pathway from agriculture is ammonia volatilization, mainly from manure and commercial fertilizer. Nationally, total emission is a function of quantity of agricultural production, which is determined by domestic and export markets, and methods of production. We show that although protein consumption is increasing in Canada, ammonia emission per person has been declining due to changes in diet. However, the decline at the individual level is offset by the increasing of population and exports of grain and livestock, so that national emissions are generally increasing. Some countries have introduced guidelines for abating ammonia emissions from farms through better practices. We have estimated the cost and possibility of mitigating ammonia losses from Canadian farms though a hierarchy of improved farming practices using cost and abatement estimates recently published by the UNECE. Public policy must weigh contrasting abatement programs and strategies, taking into account impact on environment and human health, which requires complex analyses by atmospheric scientists, ecologists and health researchers using data from emission inventories.