Plant nutrition
Plant nutrition is the study of the chemical elements and compounds necessary for plant growth, plant metabolism and their external supply. In 1972, E. Epstein defined two criteria for an element to be essential for plant growth:
This is in accordance with Liebig's law of the minimum. There are 14 essential plant nutrients. Carbon and oxygen are absorbed from the air, while other nutrients including water are typically obtained from the soil (exceptions include some parasitic or carnivorous plants). Plants must obtain the following mineral nutrients from the growing media: