Nitrogen footprints: past, present and future

The human alteration of the N cycle has evolved from minimal in the mid-19th century, to extensive in the present time. The consequences on human and environment health are significant. While much attention has been given to the extent and impacts of the alteration, little attention has been given to those entities (i.e., consumers, institutions) that use the resources that result in extensive reactive nitrogen (Nr) creation. This paper reviews a number of nitrogen footprint tools (N-Calculator, N-Institution, N-Label, N-Neutrality, N-Indicator) that are designed to provide that attention. It reviews N-footprint tools for consumers as a function of the country that they live in and the products they buy, for the institutions that people work in and are educated in, and provides a framework for people to make decisions about their resource use, and shows them how offsets can be coupled with behavior change to decrease consumer/institution contributions to N-related problems.