The present invention is directed towards methods and systems for treatment of exhaust gas from an engine. In one embodiment, an exhaust gas treatment system for a diesel engine is provided. The system includes a urea selective catalytic reduction (U-SCR) catalyst in fluid communication with a diesel engine to receive an exhaust gas flow therefrom. The system also includes a four-way catalyst in fluid communication with the U-SCR catalyst to receive the exhaust gas flow therefrom, the four-way catalyst comprising a lean nitrogen oxide (NOX) trap (LNT) and diesel particulate filter (DPF).