Nitrogen is an essential nutrient needed by all plants to thrive. Although nitrogen exists in abundance in the earth's atmosphere, relatively few plants are able to convert atmospheric nitrogen to a form they are able to use. Typically, commercial fertilizers contain nitrogen as a supplement for depleted soil. Fertilizers are divided into two main categories: “organic” fertilizers, which are naturally occurring substances such as manure, and “inorganic” fertilizers, which are manufactured through a chemical process.
Nitrogen Fertilizer: What is it?
Nitrogen fertilizer is an “inorganic” fertilizer consisting of nitrous compounds such as ammonium nitrate. It is available in different forms: liquid, which must be injected into the ground, or dry pellets, which can be applied to the surface of the soil by hand or by machine. In some cases, industrial by-products such as pure ammonia can be used as a nitrogen fertilizer, but these should be avoided as they are toxic and pose health problems in terms of handling and exposure.
Nitrogen fertilizer is produced using the Haber process, a chemical reaction first developed by German chemist Fritz Haber in 1909. Gaseous hydrogen and nitrogen react to create ammonia, which is essential for the production of fertilizers. The ammonia is then further processed to produce nitrous compounds the plants are able to absorb. About 100 million tons of nitrogen fertilizers are produced using this process each year.
Fertilizers are used to maintain the correct level of nitrogen in the soil, ensuring strong, green plants with a healthy growth rate. Nitrogen fertilizers can be used on a wide range of flora, from the household garden to commercial crops. They are currently used in one-third of the world's total crop production, including species such as maize, barley and soybean. Nitrogen fertilizers are also extensively used on commercial lawns, including a large proportion of the world's golf courses.
Where soil has become depleted of its natural nitrogen stores, fertilizers are able to make up the deficiency. This is especially important where crops are planted in the same soil each season and additional nutrients are needed for each new crop. The use of nitrogen fertilizers helps to keep nutrient levels at an optimum level, protect against disease and control weeds, resulting in healthier crops and consistent quality and quantity of yields.
Unfortunately the benefits of nitrogen fertilizer are contrasted by detrimental environmental effects associated with its use. Excess nitrogen not absorbed by the plants has been shown to leech into the groundwater, nearby rivers, and ultimately the ocean. High levels of nitrogen in the water can create algal blooms, large growths of algae that imbalance the delicate ecosystem to the detriment of other aquatic species. In addition, inorganic fertilizers are made using large amounts of finite resources such as natural gas and coal.