Are inorganic. They are made by mixing together synthetic chemicals, minerals, gasses, and inorganic waste materials.
Are expensive. The nutrients nitrogen, phosphorus, and potassium, in high concentrations are required for plant growth and bloom acceleration. The process involved in making or obtaining these ingredients results in an increased expense to the customer.
Have negative environmental impacts. The process involved in making and obtaining these ingredients has devastating effects on the environment, soil biome, wildlife, and human health.
The Process of Making or Obtaining
Ingredients for Manmade Fertilizer
The Ingredient “Nitrogen”
Nitrogen is abundant on Earth. In fact, almost 80 percent of the earth’s atmosphere is composed of nitrogen. Unfortunately, in its gas form, nitrogen is chemically and biologically unable to be used in fertilizers. To adapt, the U.S. utilizes ammonia as the foundation for all nitrogen in its manmade fertilizers. In 2019, 50% of the world's population relied on ammonia fertilizer for its food production.
To extract ammonia from the air, the following process is used. First natural gas, liquified petroleum gas, or petroleum naphtha, must be converted into gaseous hydrogen. Steam reforming is the method for producing hydrogen from hydrocarbons. The hydrogen is then combined with nitrogen to produce ammonia via the Haber-Bosch process.
The Haber-Bosch reaction runs at temperatures around 500 °C, with pressures at about 20 MPa. This reaction is an energy-hungry one. In 2010, the Haber-Bosch process emitted 451 million tons of carbon dioxide world wide, accounting for roughly 1% of the global annual CO2 emissions. This was more than any other industrial chemical-making reaction.
Phosphorus and Potassium Ingredients
Phosphorus is found in phosphate rock, while potassium is found in potash. The process used to extract both of these geological materials for use, is mining. This practice creates negative environmental impacts both during the mining activity, and after the mine has closed. Mining for phosphate and potash impacts the environment by irreparably changing the natural
landscape, eating up thousands of acres of valuable habitat that are impossible to ever truly restore. Mining displaces species, contaminates water, causes air pollution, and requires excessive water consumption.
Once mined, phosphate rock is primarily treated with sulphuric acid. This treatment produces phosphoric acid. Some of this phosphoric acid is reacted further with sulfuric acid and nitric acid. While the rest of the phosphoric acid is reacted with ammonia. Both end results are placed in fertilizers.
Several chemical processes are available to convert potash rock into potassium chloride. This potassium chloride is then supplied to fertilizer manufacturers in bulk. The manufacturer will process the potassium chloride further by granulating it, making it more usable and easier to mix.
Some Additional Environmental Impacts
The sulfuric acid plant to treat the phosphate rock will create at least two major air emissions, those pollutants being sulfur dioxide, and an acid mist. Other air emissions include heavy metals such as cadmium, mercury, and lead.
The phosphoric acid plant generates dust and fumes, both of which contain hydrofluoric acid, and/or silicon tetrafluoride.
Phosphogypsum is disposed of as a slurry to a storage/settling pond, waste heap, and by some operations, into marine life environments.
Manmade fertilizers do not improve soil conditions, and can actually degrade them, killing beneficial soil microfauna, and larger organisms such as earthworms that convert dead remains into humus. Humus is the nutrient-rich organic matter which helps make the soil more fertile. It also helps prevent disease in plant life.
Manmade fertilizers offer precise amounts of ingredients and can benefit plant life almost immediately. However, rapid fertilization is unnatural, resulting in only a small amount of nitrogen actually assimilating into the plant. Excess nutrients in the soil and/or changes in soil pH, leading to nutrient lockout.
Nutrient lockout not only prevents plants from further feeding, resulting in loss of plant life, but the excess ground nutrients will leach out. Nitrates in manmade fertilizers are highly mobile and easily move with water. When the rainfall is heavy, nitrates move downward in the soil. Eventually the excess nitrates will leach into above- and below-ground water systems.
Once in human drinking water, excess nitrates can cause both urinary and kidney system disorders. Excess nitrates can be toxic to newborns, resulting in death if not treated. Additionally excess nitrates have been found to be carcinogenic. Nitrosamines, another byproduct of the nitrates in fertilizer, caused tumors in laboratory animals.
In above-ground water ways, leaching of nutrients can cause eutrophication. Eutrophication is when excess amounts of fertilizer cause algae to bloom. As the algae decomposes, it uses up all available oxygen within the water. The chemical composition of the waterbed floor changes, resulting in increased phosphorus amounts being released. Thus, a positive feedback loop occurs, which keeps the waterbed in that permanent state. This feedback loop is the cause behind dead zones in our oceans.
A dead zone is where the water is unable to hold onto oxygen, and nothing is able to survive. In 2021 Earth had dead zones covering over 6,000 square miles in its oceans. Historically, dead zones have directly coincided with each prior mass extinction event.