Matt and Erin have a special guest on this podcast to help understand life cycle assessments. Dr. Kurt Rosentrater is an engineer and associate professor at Iowa State. Kurt explained the basics of conducting a life cycle assessment, including assumptions and resulting complications that come with this tool. They focused on a recent example looking at environmental impacts in four major crops. Here is the link to the paper so you can follow along with figures: http://www.ingentaconnect.com/content/iop/erl/2015/00000010/00000009/art094016. The assessment showed freshwater ecotoxicity impact in soybean increased 3-fold from 2002 to 2012. The authors claimed the insecticides used to control soybean aphid was an important factor. Corn, cotton and wheat did not have a significant increase of impact over the study duration. Learn more about Kurt's research and teaching program here: http://www.abe.iastate.edu/kurt-a-rosentrater-assistant-professor/.