Agriculture is the most primitive occupation of the people which mainly needs land to grow different crops for food and as raw materials for different industries. Industrial use of agriculture for supplying raw materials came much later. Originally land was used for agriculture to supply food for human beings by the use of organic manures particularly animal dung. At the beginning land was used in its natural form to grow food. Land contains natural humus that supplies nutrients for crop. But people began to think that natural fertility of land cannot supply sufficient food crops for human to survive. This belief became concrete when Thomas Robert Malthus wrote in 1798 that population grows at a faster rate than the growth of food by the famous quote, “food grows at arithmetic progression and population grows at geometric progression.” As we cannot survive without food; so we have to grow more food to feed the fast growing population. To grow more food we have to add plant nutrition and research on plant nutrition began perhaps in 19th century after the publication of Malthusian Theory. In the 19th century a German chemist Justus von Liebig started the modern science of plant nutrition denouncing the vitalist theory of humus. For the first time he argued the importance of ammonia and in later course tried to promote the idea of using inorganic minerals to plant nutrition. Thus the concept of using fertilizer began and different types of inorganic fertilizer are manufactured and in this manner Erling Johnson in 1927 developed an industrial method of producing nitrophosphate.During the 19th century in England fertilizer companies were established and commercial production of inorganic fertilizer began and the debate on uses of organic versus inorganic was also started. In India widespread use of inorganic fertilizer began in 1968 which ushered a Green Revolution by large production of wheat using High Yielding Varieties of Seeds (HYV Seeds) ‘The HYV Seeds was first introduced in India by Dr.Norman Borlaug and the credit for introducing the Green Revolution goes to Dr. M.S.Swaminathan WHAT ARE FERTILIZERS?
Fertilizers can be defined as a chemical or natural substance added to soil to increase its fertility. Fertilizers contain nutrients that promote plant growth. Created from numerous ingredients, derived from animals and commercial products, fertilizers are necessary for maximizing a plant's health and size. Fertilizers can be composed of organic or inorganic material of natural or synthetic origin that is added to a soil to supply one or more plant nutrients essential to the growth of plants. Manure and compounds contain nutrients like nitrogen, phosphorus, and potassium, which are spread on or worked into soil to increase capacity of crop yield. Fertilizers are available in various forms. The most classic form is solid fertilizer found in granulated or powdered forms. The next most common form is liquid fertilizer. It has some advantages like its effectiveness is immediate and its coverage is wide.There are also slow-release fertilizers most notably fertilizer spikes, tabs, etc. which reduce the problem of "burning" the plants due to excess nitrogen. Recently, organic fertilizer is on high rise as people are resorting to environmental friendly (or 'green') products. Though organic fertilizers usually contain a lower concentration of nutrients, this lower concentration avoids complication of nitrogen burn harming the plants. Moreover ,organic fertilizers such as compost and worm castings break down slowly into complex organic structures (humus) which constructs the soil's structure and moisture- and nutrient-retaining capabilities. CLASSIFICATION OF FERTILIZERS:
Fertilizers can be broadly classified into two types:
(1)Organic Fertilizers or Chemical Fertilizers
A chemical fertilizer may be as defined as...