NOX Emissions: Staged combustion is a widely used option for lowering NOX emissions from a high-nitrogen fuel such as poultry litter. With staged combustion, combustion conditions are somewhat more reducing and less fuel nitrogen is converted to NOX. Ammonia injection under appropriate conditions also reduces NOX emissions, and the naturally occurring ammoniacal nitrogen in poultry litter helps keep NOX emissions low. In some cases, more rigorous NOX control measures, such as selective catalytic reduction, may be required for poultry litter