All higher plants, with the exception of carnivorous ones, utilize nutrients of an exclusively inorganic (mineral) nature. Essential nutrients are defined as requisite for normal functioning of a plant's physiological and metabolic processes and cannot be substituted by other chemical elements or compounds. The essential nutrients are divided into macroelements, consisting of carbon (C), hydrogen (H), oxygen (O), nitrogen (N), phosphorus (P), sulphur (S), potassium (K), calcium (Ca), and magnesium (Mg), and into microelements, consisting of iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), molybdenum (Mo), boron (B), and chlorine (Cl), with tissue concentrations that may be 100 to 10,000 times lower than those of macroelements. Nickel (Ni), cobalt (Co), sodium (Na), and silicon (Si) are difficult to classify at this time because the essential need for these elements in all higher plants has not yet been confirmed. Plants obtain most of their H, C, and O in the form of carbon dioxide (CO2) and oxygen supplied by air and as water supplied by the soil. Many of all the other nutrients are absorbed from the soil, but plant foliage may also absorb small quantities of nutrients from rainwater, e.g., nitrate (NO3), sulfur dioxide (SO2), and others.
Was this article helpful?