FERTILIZERS

Fertilizers are chemical compounds applied to promote plant and fruit growth. Fertilizers are usually applied either through the soil (for uptake by plant roots), or by foliar feeding (for uptake through leaves). Fertilizers can be placed into the categories of organic fertilizers (composed of plant or animal matter), or inorganic fertilizers (made of simple, non-carbonaceous chemicals or minerals).

'Organic' fertilizers are composed of 'naturally' occurring compounds such as peat manufactured through natural processes (such as composting) or naturally occurring mineral deposits; or in the case of 'inorganic' fertilizers, manufactured through chemical processes (such as the Haber process) or from naturally occurring deposits that have been chemically altered (e.g. concentrated triple superphosphate).

Properly applied, organic fertilizers can improve the health, and productivity of soil and plants as they provide different essential nutrients intended to encourage plant growth. Organic nutrients increase the productivity of soil organisms such as microbes which aid plants in absorbing nutrients gradually. Chemical fertilizers have long-term adverse impact on the organisms living in soil and a detrimental long term effect on soil productivity of the soil

Nitrogen fertilizer is often synthesized using the Haber-Bosch process, which produces ammonia . This ammonia can be applied directly to the soil, or used to produce other compounds (notably anhydrous ammonium nitrate and urea). These concentrated products may be used as fertilizer or diluted with water to form a concentrated liquid fertilizer, UAN . Ammonia can also be used in the Odda Process in combination with rock phosphate and potassium fertilizer to produce compound fertilizers such as 10-10-10 or 15-15-15 .

The production of ammonia currently consumes about 5% of global natural gas consumption, which is somewhat under 2% of world energy production. Natural gas is overwhelmingly used for the production of ammonia, but other energy sources, together with a hydrogen source, can be used for the production of nitrogen compounds suitable for fertilizers . The cost of natural gas makes up about 90% of the cost of producing ammonia. The price increases in natural gas in the past decade, along with other factors such as increasing demand, have contributed to an increase in fertilizer price .

Nitrogen-based fertilizers are most commonly used to treat fields used for growing maize, followed by barley, sorghum, rapeseed, soyabean and sunflower . One study has shown that application of nitrogen fertilizer on off-season cover crops can increase the biomass of these crops, while having a beneficial effect on soil nitrogen levels for the cash crop planted during the summer season