Samuel William Johnson (July 3, 1830 – July 21, 1909) was an American agricultural chemist. He promoted the movement to bring the sciences to the aid of American farmers through agricultural experiment stations and education in agricultural science. Johnson, working in the 19th century, covered various aspects of farming that today would be called both organic and nonorganic. His work included exposing frauds in artificial manures (some of which would today be called chemical fertilizers). Source: Wikipedia (en)