Agricultural applications of fertilizers have increased dramatically since the middle 1960s, and nutrient loads from agriculture now present serious water quality concerns. In addition to local impacts on receiving waters, nutrient loads from row crop agriculture are suspected as a primary contributor to hypoxia in the Gulf of Mexico. Wetland restoration is viewed as one of the most promising strategies for reducing surface water contamination in agricultural watersheds and in particular for reducing nitrate loads to the Mississippi River and its tributaries. However, using this strategy effectively requires recognition of (1) the special characteristics of nutrient transport in agricultural landscapes, (2) the primary controls on wetland nutrient transformations at high nutrient loading rates, and (3) the variable and dynamic nature of non-point source hydraulic and nutrient loading rates. This is illustrated by specifically examining the potential of wetlands to ameliorate the problem of non-point source nitrogen loads in the Midwest Corn Belt: considering in turn nitrogen transport pathways, hydraulic and nitrogen loading dynamics, and environmental controls on nitrogen processing in receiving wetlands.