Justus Liebig
Liebig invented new methods for the analysis of organic materials. He showed that, to grow, plants need (as well as water and sunlight) carbon dioxide, minerals and nitrogen compounds. He discovered that nitrogen was an essential plant nutrient, and invented the first nitrogen-based fertiliser. His Law of the Minimum stated that a plant's development is limited by the one essential mineral that is in the shortest supply. He described the effect of individual nutrients on crops.