Abstract:
All living organisms require a regular supply of nutrients and any imbalance will result in abnormal development. The essential nutrients include an energy source, carbon and hydrogen sources, organic growth factors and mineral nutrients. The most widely known of the mineral nutrients are the macro-elements such as nitrogen, phosphorus, potassium, calcium, magnesium, sulphur, sodium and chlorine. The micro-elements, or trace elements, which were once thought to be a form of contamination are now known to be important and include iron, zinc, chromium, manganese, copper, molybdenum, boron and vanadium. All the micro-elements listed are necessary for the successful growth of higher plants. Selenium, iodine and cobalt are also needed for the growth of animals but are not necessary for plants.