vue - MAGE Podcasts: A Short History of Agricultural Fertilizer

A Geography professor explains the evolution of the use of fertilizer starting around 1600. There are many other Geography skill/concept videos at "MAGE Geography". MAGE is a non profit organization which produces free materials for Minnesota students and teachers of Geography. Check out the database of MAGE podcasts at: http://lt.umn.edu/mage/podcasts/