In order to sustain the increasing human population, crops have to be grown efficiently and effectively. Currently, fertilizers are used all around the world to increase plant growth and sustain the population. Fertilizers are any substance that increases plant growth, and usually contain nitrogen and phosphorus, which are both important nutrients that are needed for all forms of life. Therefore, by applying fertilizers to crops, the crops are able to grow more easily due to these crucial nutrients being comfortably provided to the crops. 

As mentioned before, nitrogen is a crucial nutrient that is needed for all forms of life. Humans obtain nitrogen by consuming other animals who have also consumed nitrogen, and these animals may have obtained nitrogen by also consuming other organisms who have consumed nitrogen. However, the source of nitrogen for all animals is plants. Plants take up nitrogen from the soil or directly through bacteria that live on their roots, and pass on the nitrogen by being consumed by herbivores. Some special plants have formed a mutualistic relationship with a special type of bacteria living on their roots, where both species benefit as the plants are able to obtain nitrogen from the bacteria while the bacteria receive other nutrients from the plants along with a place to live. 

These special bacteria are often called nitrogen fixers because they “fix” nitrogen from the atmosphere into a usable form by organisms. Through a complex process, the bacteria absorbs nitrogen gas and converts it into ammonium, which is then able to be transformed into a form of nitrogen so that it can be absorbed and consumed by other organisms. However, because only these special bacteria can convert nitrogen gas into an available form of use, plant growth is heavily limited.

On the other hand, fertilizers provide excess amounts of nitrogen when administered, instead of the limited amounts that are provided by nitrogen fixers. This is exactly why fertilizers are effective for plant growth. However, fertilizers have their own downsides. Only around 50% of nitrogen from fertilizers is absorbed by the crops, meaning that around 50% of nitrogen is lost and is often released into the environment. This negatively impacts the environment.

Excess nitrogen that has not been used and is released into waterways causes eutrophication, which is simply excess amounts of nutrients present in waterways. Eutrophication then promotes the growth of massive amounts of algae and causes algal blooms, and the algae uses up all of the oxygen in the waterway. This destroys the habitats of aquatic animals, as these animals require oxygen to survive. Additionally, excess nitrogen administered into the soil can be transformed by microorganisms and released into the atmosphere in the form of Nitrogen Dioxide, which is a harmful greenhouse gas trapping heat and promoting climate change. 

Fertilizer use is crucial to crop growth, as nitrogen is an element that is hard to obtain but is important to promote growth in plants. However, fertilizers also possess several negative impacts on the environment, making excessive fertilizer use dangerous. Therefore, many types of scientists including microbiologists, soil scientists, chemists, plant biologists, and computer scientists are working hard to figure out a method to balance the amount of fertilizer administered into crops, in order to maximize plant growth while minimizing the harmful negative effectives to the environment. 

Sources: 

1 (all information from this report comes from this article): https://kids.frontiersin.org/articles/10.3389/frym.2020.00063#:~:text=Fertilizers%20are%20added%20to%20crops,and%20to%20produce%20more%20food.