Here's something to think about the next time you clean your windshield.

Hosted by: Hank Green
----------
Fritz Haber: https://www.youtube.com/watch?v=tdEE5uvFhOM
Support SciShow by becoming a patron on Patreon:
https://www.patreon.com/scishow
----------
Dooblydoo thanks go to the following Patreon supporters—we couldn't make SciShow without them! Shout out to Kevin Bealer, Mark Terrio-Cameron, KatieMarie Magnone, Patrick Merrithew, Charles Southerland, Fatima Iqbal, Benny, Kyle Anderson, Tim Curwick, Scott Satovsky Jr, Philippe von Bergen, Bella Nash, Bryce Daifuku, Chris Peters, Patrick D. Ashmore, Charles George, Bader AlGhamdi
----------
Looking for SciShow elsewhere on the internet?
Facebook: http://www.facebook.com/scishow
Twitter: http://www.twitter.com/scishow
Tumblr: http://scishow.tumblr.com
Instagram: http://instagram.com/thescishow
----------
Sources:

http://qi.com/infocloud/guano
http://99percentinvisible.org/episode/guano-mania/
http://ushistoryscene.com/article/guano-islands-bird-turds/
http://www.atlasobscura.com/articles/when-the-western-world-ran-on-guano
http://www1.american.edu/ted/guano.htm
http://americanhistory.si.edu/blog/what-load-guano-5-facts-you-didnt-know-about-bird-poop
http://americanhistory.si.edu/norie-atlas
http://mygeologypage.ucdavis.edu/cowen/~gel115/115CH16fertilizer.html
http://manoa.hawaii.edu/hpicesu/papers/1994_the_guano_islands.pdf
https://books.google.com/books?id=LbIEXKafflMC&q
http://www.academia.edu/1788506/Influence_of_Seabird_guano_and_Camelid_dung_fertilization_on_the_nitrogen_isotopic_composition_of_field-grown_maize_Zea_mays_
http://www.plantphysiol.org/content/116/2/447.full
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0033741
http://modernfarmer.com/2015/05/get-a-load-of-our-manure-guide/

Images
https://commons.wikimedia.org/wiki/File:The_Guano_and_Peruvian_Booby_Birds_(6990616208).jpg
https://upload.wikimedia.org/wikipedia/commons/3/3f/DSCN5766-guano-glantz_crop_b.jpg
https://en.wikipedia.org/wiki/Guanay_cormorant#/media/File:Leucocarbo_bougainvillii_qtl2.jpg