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Fertilizers (or fertilisers) are substances that supply plant nutrients or amend soil fertility. They are the most effective (30 -80 per cent increase in yields) means of increasing crop production and of improving the quality of food and fodder. Fertilizers are used in order to supplement nutrient supply in the soil, especially to correct yield-limiting factors. Fertilizers are applied to promote plant growth; the main nutrients present in fertilizer are nitrogen, phosphorus, and potassium (the ’macronutrients’) and other nutrients (’micronutrients’) are added in smaller amounts. Fertilizers are usually directly applied to soil, and can also be sprayed on leaves as a foliar feeding. Organic fertilizers and some mined inorganic fertilizers have been used for many centuries, whereas chemically synthesized inorganic fertilizers were only widely developed during the industrial revolution. Increased understanding and use of fertilizers were important parts of the pre-industrial British Agricultural Revolution and the industrial Green Revolution of the 20th century. Inorganic fertilizer use has also significantly supported global population growth  it has been estimated that almost half the people on the Earth are currently fed as a result of artificial nitrogen fertilizer use. Fertilizers typically provide, in varying proportions:
The macronutrients are consumed in larger quantities and are present in plant tissue in quantities from 0.2% to 4.0% (on a dry matter weight basis). Micronutrients are consumed in smaller quantities and are present in plant tissue in quantities measured in parts per million (ppm), ranging from 5 to 200 ppm, or less than 0.02% dry weight. The nitrogen-rich fertilizer ammonium nitrate is also used as an oxidizing agent in improvised explosive devices, sometimes called fertilizer bombs, leading to sale regulations. 
Tennessee Valley Authority: "Results of Fertilizer" demonstration 1942 
A large, modern fertilizer spreader
From Wikipedia, the free encyclopedia : Wholesale of pesticides and fertilizers |
