Chem. analyses of plants grown in the field and greenhouse show that nutrient absorption by plants differs with kind of plant, supply of nutrient, and various ecological factors. Within one species, however, and to a less extent within a group of related plants, more or less characteristic curves of nutrient absorption may be obtained. Absorption should be plotted against period of development of the plant rather than against calendar period, so as to reduce climatic and seasonal factors. Nutrient absorption precedes synthetic processes in plants and usually reaches 1 or 2 peak periods, varying in this respect, and in intensity with species. Nutrient supply should be correlated with the course of nutrient absorption. Excess or deficiency of nutrients relative to the plant''s needs may be deleterious or uneconomic, especially in the case of N. Excesses of P and K are seldom harmful but may be uneconomic. The findings are applied to the efficient and practical use of fertilizers for cultivated plants.