Synthetic Fertilizers

The ammonium carbamate then loses a molecule of water to produce urea [57-13-6] CO(NH2)2- Commercially, this is probably the most important reaction of carbon dioxide and it is used worldwide ia the production of urea (qv) for synthetic fertilizers and plastics (see Amino resins Carbamic acid). 

The natural supply of nitrogen available to plants from the nitrogen cycle is limited. To meet the growing demands for agriculture crops, nitrogen is added to soil in the form of fertilizers. An estimated one-third of the human population is fed as a result of the use of synthetic fertilizers. 

Because the nitrification and denitrification processes both form N2O as a by-product, control of anthropogenic N inputs to the soil in the form of synthetic fertilizers or manure would affect the amount of N2O produced... 

Chemical plants are a series of operations that take raw materials and convert them into desired products, salable by-products, and unwanted wastes. Fats and oils obtained from animals and plants are hydrolyzed (reacted with water) and then reacted with soda ash or sodium hydroxide to make soaps and glycerine. Bromine and iodine are recovered from sea water and salt brines. Nitrogen and hydrogen are reacted together under pressure in the presence of a catalyst to produce ammonia, the basic ingredient used in the production of synthetic fertilizers. 

Borlaug N (1995) Fertilizer use in Sub-Saharan Africa - keynote address to the roundtable of science advisors for science-led development in Africa. Maputu, Mozambique Bulluck III LR, Brosius M, Evanylo GK, Ristaino JB (2002) Organic and synthetic fertility amendments influence soil microbial, physical and chemical properties on organic and conventional farms. Appl Soil Ecol 19 147-160... 

The transition from conventional to organic and low-input farming is accompanied by changes in an array of soil chemical properties and processes that affect soil fertility. Fundamental differences, both qualities and quantitative, in the flow and processing of nutrient result from the use of cover crops, manure and compost applications, and reduction or elimination of synthetic fertilizers and pesticides. These changes affect nutrient availability to crops either directly by contributing to nutrient pools or indirectly by influencing the soil chemical and physical environment. 

Yardim, E.N. and Edwards, C.A. 2003. Effects of organic and synthetic fertilizer sources on pest and predatory insects associated with tomatoes. Phytoparasitica 31(4) 324-329. 

Natural and Synthetic Fertilizers Help Restore Soil Fertility... 

NATURAL AND SYNTHETIC FERTILIZERS HELP RESTORE SOIL FERTILITY... 

The effect that nitrogen-containing synthetic fertilizers can have on yields is illustrated in Figure 15.13. It requires a lot of energy to mine and refine synthetic fertilizers, however, and so they are expensive. For example, of the total energy required to produce corn in the United States, at least one-third is needed to produce, transport, and apply the fertilizer. Nevertheless, synthetic fertilizers are widely used, and our present food supply depends on them. 

Poor maintenance of topsoil is also a major concern. Synthetic fertilizers have no organic bulk and do not provide a food source for soil microorganisms and earthworms. Over time, a soil treated with only these fertilizers loses biological activity, which diminishes the soil s fertility. Soils void of organic bulk become chalky and susceptible to wind erosion. Chalky soils lose their capacity to hold water, which means that more applied fertilizer is leached away. Ever-increasing amounts of fertilizer are thus needed. 

Organic farming Farming without the use of pesticides or synthetic fertilizers. 

What advantages do mixed synthetic fertilizers have over compost ... 

What advantages does compost have over mixed synthetic fertilizers ... 

What is missing from synthetic fertilizers that makes them harmful to soil ... 

When only synthetic fertilizers are used on a crop, the quantity used needs to be increased over time. Why ... 

Earthworms are repelled by the high concentrations of nutrients in soils treated with synthetic fertilizers. How might this affect the soil structure ... 

Which is better for a plant an ammonium ion from compost or an ammonium ion from synthetic fertilizer ... 

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