The concepts of precision agriculture (PA) and sustainability are inextricably linked. From the first time a global positioning system was used on agricultural equipment the potential for environmental benefits has been discussed. Intuitively, applying fertilizers and pesticides only where and when they are needed, should reduce environmental loading. This paper will explore the realities of PA and sustainability. Exactly how can PA contribute to sustainability? Have the environmental benefits been measured? The paper will start with definitions of sustainable agriculture and precision farming. The next section will review research on the environmental impacts of PA. The last section will provide an example of how site-specific information and variable rate application could be used in maintaining profitability while reducing N applications