Measuring sustainabiilty in agriculture - focusing on outcomes

A white paper I wrote (along with my colleagues Tim Boucher and Samantha Atwood) is now available at:
http://www.nature.org/science-in-action/science-features/measuring-sustainability-in-agriculture-focusing-on-outcomes.xml

The basic premise is that the measure whether or not agriculture is truly sustainable we have to get past just measuring practices (what we do, such as conservation tillage or riparian buffers) and move to measuring outcomes (water quality & quantity, soil quality, etc.). We review the literature and suggest several metrics for environmental variables, although we do not include agronomic variables such as yield which are part of overall sustainability.