Dr. William H. Patrick, Jr. was a pioneer scientist on the role of redox chemistry of flooded soils. His early work on redox chemistry of carbon and nitrogen transformations and transport processes in flooded soils is discussed. Nitrogen and carbon transformations play an important role in soil emissions of certain greenhouse gases (carbon dioxide, methane, and nitrous oxide). Both carbon and nitrogen field flux measurements from wetland soils, as well as transformations determined using laboratory microcosms where redox conditions are controlled are presented. We will track a progression of the work of Dr. Patrick and some of his colleagues leading to more recent work on the role of redox conditions as an important parameter governing production and emission of methane and nitrous oxide from irrigated rice fields as well as natural wetlands.