<h1>PLANT NUTRIENTS AND NUTRIENTS CYCLE<strong></strong></h1> CONTENT <ol> <li>Meaning of Macro and Micro Nutrients</li> <li>Sources, Functions and Deficiency Symptoms of Plant Macro Nutrients</li> <li>Sources, Functions and Deficiency Symptoms of Plant Micro Nutrients</li> <li>Factors Affecting the Availability of Nutrients</li> <li>Methods of Replenishing Soil Nutrients</li> <li>Organic Agriculture</li> </ol>   <h2>Meaning of Macro and Micro Nutrients</h2> Nutrients are elements or substances that provide nourishment for the growth, development, metabolism and general well-being of plants. The most basic nutrient elements are carbon, hydrogen and oxygen, which are usually obtained from the air, soil or water medium in which the plant grows. All the other elements can be classified into two groups, macro and micro nutrients. <ol> <li><strong>Macro/Essential/Major Nutrients</strong>: Macro nutrients are mineral elements required by crops in a relatively large quantity. Examples of macro- nutrients are nitrogen, phosphorous , potassium, magnesium, calcium and sulphur.</li> <li><strong>Micro/Trace/Non Essential/Minor Nutrients</strong>: Micro nutrients, also known as trace elements are mineral elements required by crops in small quantities. Examples of micro nutrients are iron, manganese, boron, molybdenum, copper, zinc. Others appear to be helpful for the growth of certain species of plants. The functions and deficiency symptoms of these nutrients are summarized below.</li> </ol>