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Nitrogen fertilizer is a compound that is added to plants or lawns to stimulate growth. The nitrogen stimulates chloroplasts in plants, which are responsible for the process of photosynthesis. Plants that do not have enough nitrogen will turn yellow and eventually perish from a lack of food.
The development of nitrogen fertilizer began in 1905 with the German chemist Fritz Haber. Haber discovered a way to fixate nitrogen from the air. Fixation is the process by which a gas, such as nitrogen, is converted into a usable compound. In this case, Haber was able to convert gaseous hydrogen and nitrogen into ammonia. He received a Nobel prize for his work in 1918.
Originally, Haber's process was used to synthesize nitrates for Germany during the First World War, to aid in the production of explosives. A refinement of his method led to the ability to create ammonium sulphate for use in soil. Once this process was adapted to work on a large scale, nitrogen fertilizer was born.
There are two common forms of nitrogen used for plant growth. The first is natural nitrogen, which is found in decaying plant or animal matter. This is why compost is used on lawns or gardens — the manure and other material in it releases nitrogen into the soil.
The second form of nitrogen fertilizer available is commercially synthesized. In this case, the nitrogen is present in the form of ammonium or nitrate. Ammonium-based fertilizers bond securely with soil, but release their nitrogen slowly into a plant. Those based around nitrates are quickly absorbed by a plant, but can be easily washed away by water in a process known as leaching.
Natural nitrogen takes longer to be used by a plant than either commercial form, but does not come with the same risks. Improper application of commercial fertilizer can lead to groundwater contamination. The widespread use of commercial nitrogen fertilizer is now a serious environmental concern as contaminated runoff water has begun to adversely affect sea plants around the world. Extra nitrogen present in the water has caused unrestrained algae growth in some bodies of water, which then results in massive algae death and decay. This happens because, as water in the immediate area is depleted of oxygen, the algae die. subsequently, this kills large amounts of animal life that need it for food.
Nitrogen lawn fertilizer also contains phosphorous and potassium, since phosphorus assists in root growth and potassium is needed for water movement. A bag of fertilizer will list the percentage of each compound present in the fertilizer. One marked 10-10-10 means that each compound accounts for 10% of the bag by weight, and the other 70% of the bag is simply an inert chemical.
Properly applying nitrogen fertilizer is important. Too much will kill a lawn as surely as too little. Bags will list suggested amounts to use, based on the size of lawn being fertilized. Ideally, apply the material when the lawn is wet and likely to stay that way for a while. This can prevent the nitrogen from burning the grass, or making it yellow and brittle.