"it was easy for me to figure out what had worried Jethro Tull. Not Jethro Tull the 1970s rock band—Jethro Tull the agricultural reformer of the 18th century." (Thanks MM, who was also one of my music gurus)
A superb article on soils and farming from National Geographic. Have I ever told you that I trained as a soil scientist and still teach it?