What is the Role of the Decomposers in the Nitrogen Cycle?

Nitrogen is the most abundant element in Earth’s atmosphere and, while oxygen gets a lot of praise, it’s nitrogen that is essential to establishing DNA and promoting the growth of plants.

It can be found in everything, from the soil that we grow crops in, to the water and air, and that we consume on a daily basis. 

This doesn’t mean nitrogen is harmless as animals and plants need a specific amount, too much or too little nitrogen can lead to low or toxic crop yields.

When trying to discover which conditions are best for growing crops with just the right levels of nitrogen, who else can we look to other than Mother Nature herself?

By understanding the nitrogen cycle, we can estimate how much nitrogen a certain crop needs, all while being sensitive to the environmental needs of the area.

What is The Nitrogen Cycle?

So, what is the nitrogen cycle?

You’ve probably heard of the water cycle and have seen the handy diagrams showing how it works.

The nitrogen cycle works in much the same way, it’s the naturally occurring process by which nitrogen moves from the atmosphere into the ground and the sea, where it then makes its way back into the atmosphere for the cycle to repeat.

During this cycle, nitrogen is used for vital biological processes in both terrestrial and marine life. Even bacteria play a part in the process. 

Stage One: Nitrogen Fixation

In some more detail, the cycle begins when nitrogen gas in the atmosphere undergoes a transformation so it can be used by plants.

This fixation is achieved when nitrogen can react with oxygen, usually through lightning and other natural factors, to produce nitrogen oxide or dioxide. These can enter into the ground.

In more recent years, industrial fertilization can also fix nitrogen gas, usually through producing ammonia and ammonium nitrate. The fixed nitrogen is used by plants to develop and grow or otherwise exist in the soil through bacteria or microorganisms in water sources.

Stage Two: Mineralization

Mineralization takes place in the soil more than anywhere else and is just when a plant’s nutrients are used up. This brings the plant’s lifespan to a natural end, where it dies and decomposes.

Mineralization is the name for when microbes act on organic materials, decomposing it and producing more nitrogen in the air to be used by future plant life through natural ammonia and ammonium if water is present.

Stage Three: Nitrification

Nitrification also happens in the soil and is just when the ammonia produced through mineralization becomes nitrite compounds through the introduction of oxygen.

Nitrites are then usable not by the plants or wildlife, but by the bacteria that can transform nitrites into nitrates, which is beneficial for growing life. These bacteria are called Nitrosomonas, if turning ammonia into nitrites, and then Nitrobacter if turning nitrites into nitrates, but both need the presence of oxygen to work.

Stage Four: Immobilization

This fourth stage is where the effects of mineralization start to reverse. Through mineralization and immobilization, the amount of nitrogen in the soil is regulated so that it doesn’t exceed or fall below useful levels for most areas.

Immobilization is when the ammonium and nitrate that have been created are eaten up by microorganisms, depriving plants of these nitrogen forms. This may sound negative, but it’s important that nitrogen levels in the soil be regulated otherwise both the plants and the microorganisms will suffer.

Stage Five: Denitrification

Denitrification is where the nitrogen, usually as nitrates, return to the air and is reconverted into atmospheric nitrogen by bacteria.

Becoming a gas again, the nitrogen can then repeat the cycle and benefit the growth of crops long into the future.

What is a decomposer?

Now that we have an understanding of the nitrogen cycle, what is the place of decomposers in it?

A decomposer is a term for an invertebrate, fungus, or bacteria that decompose organic material.

Put simply, they are the organisms that eat other dead organisms, including plant life and other animal waste products, and breaks them down into more basic materials by doing so.


This primarily takes place in the mineralization stage of the nitrogen cycle, where these decomposers transfer organic nitrogen and nitrogenous waste into ammonium by decomposing plant life.

Most biomatter, when decomposed, helps to eventually return nitrogen products back to the nitrogen cycle, however. They do this by producing ammonia or ammonium if water is present, where it can continue being used by microorganisms in the soil before returning to the atmosphere when denitrification occurs.

How do they interact?

Without decomposers, we wouldn’t just have the problem of dead animal waste and plant life lying around, but in that detritus we’d also have a lot of nitrogen that isn’t being re-contributed back into the environment, stifling the growth of future plants and the animals who’ll live off of them.

That includes us, too, making decomposers a vital part of the continuation of crop growth and life on Earth.

If nitrogen weren’t as abundant in the atmosphere as it is, thanks to the decomposers, then the continued growth and expansion of living matter on both land and sea would be severely restricted.

Plantlife would grow very poorly, if not at all because there wouldn’t be enough nitrogen to go around, and a lack of nitrogen would even interfere with the food-web structure of an area.

How do we know this?

We’ve already seen it happen through hypoxia or anoxia where, whether for rare, naturally occurring reasons or industrial manipulation, the nitrogen levels of a piece of land have fallen below average.

Algal blooms form on water sources and the habitats of entire areas degrade, affecting the local ecosystems and food webs, and potentially increasing the risk that parasitic diseases develop in that area.

So, it’s no understatement when we say that the role of decomposers in the nitrogen cycle is quite essential. Every healthy crop needs to have an established nitrogen cycle, which means a good decomposer presence if you want its yields to be bountiful and self-sustaining.

1 thought on “What is the Role of the Decomposers in the Nitrogen Cycle?”

  1. Interesting article. Thank your for publishing it. I think you have one important edit to make. You should replace the word “understatement” with the word “overstatement” in your second to last paragraph. I think it would be helpful to me to include some of the formulas for the chemistry that happens in this cycle. What are the beginning compounds and what compounds or molecules do they turn into in the nitrogen cycle.

Leave a Comment

Your email address will not be published. Required fields are marked *