A historic book that pulled together work from multiple scientists to explain what elements plants need and where they get them from. This understanding was the scientific foundation for synthetic fertilizer.
Chemists knew that plants were made of carbon, hydrogen, oxygen, and nitrogen, but what is the source of those elements? In particular, which ones come from the soil and are thus depleted by the harvest, requiring renewal through manuring, rotation, or fallowing? Liebig said that plans get carbon from the atmosphere (CO2), hydrogen from water, and oxygen from both, but nitrogen has to come from the soil (specifically, he believed, from ammonia, and in particular not from atmospheric nitrogen, which is inert).
Pair with The Alchemy of Air.