Nutrient cycle in ecosystem


5 basic nutrients existing in their original form are carbohydrates, proteins, lipids, vitamins, and minerals. However, after the consumption of the nutrients, they get converted into simpler forms, for instance, carbohydrates become glucose, proteins release amino acids and the complex lipids become simpler molecules. This will give us a clue that there is some change in the nutrients even after consuming them. In order for the nutrients to gain their simpler forms, they must undergo some cyclic processes. Similarly, in our atmosphere many types of cycles take place and one such process is the Nutrient cycle. Another notable phenomenon is that, after the utilization of nutrients by the body, they get converted into waste material such as ammonia, urea, uric acid and many more elements, The wastes excreted by the body are no more going to be the end products, instead, they get into the soil and the plants reabsorb them resulting in the conversion of wastes into starch, proteins and minerals once again. Hence energy can neither be created and nor be destroyed but they can only change in their form. One of the ways of conversion of energy from one form to another is through the nutrient cycle. There are many nutrient cycles in our ecosystems. The very purpose of a nutrient cycle is to convert complex substances into the usable and simpler form. Hence, nutrient cycle or ecological recycling is the process of exchange and movement of nutrients between their organic to inorganic forms that ultimately help in releasing them into the original production cycle. For example, food is consumed in the form of carbohydrates, protein, fats, but the end products will be urea, uric acid, ammonia will enter the system; here only the form is changed but the actual energy is not lost. In other words, the movement of nutrient elements through the various spheres of an ecosystem ( lithosphere, hydrosphere, and biosphere) to change themselves into different forms is called nutrient cycling.


Table of Contents

1. Introduction

2. Forms of nutrient cycle 

3. Carbon Cycle

4. Phosphorus cycle


Forms of nutrient cycle 

Nutrient cycles are of 2 forms namely, gaseous (nitrogen cycle and carbon cycle) and sedimentary form (, Sulphur, and phosphorus cycles). The net amount of nutrients available in their original form (carbon, nitrogen, phosphorus, calcium, etc) is called standing state at that point of time but some nutrients will be utilized for the body activities of individuals.  Some of the common nutrient cycles are as described below.


Carbon Cycle 

Earth has a huge reservoir of carbon dioxide because carbon is the basic building block of every organic material.  The majority of the carbon is found the oceans (71 %), and some extent in the earth’s crust and the rest of the amount is found within the living organisms. Some of the material goods that we use in our day to day life also has carbon. Our atmosphere hardly has 1% of the total carbon. The carbon is not a constant element, but it undergoes a cyclic change . one of the examples of the carbon cycle is shown in the image below.

Diagram of the carbon cycle- source

Carbon cycle


Some of the ways in which carbons moves across various forms are:

1. Photosynthesis: C02 is consumed by the plants during photosynthesis to produce food in the form of organic molecules like glucose . Glucose has some percentage of carbon in its molecular form.

2. Combustion: Through burning, the wood, fossils and wastes will be degraded, so that the solid carbon is converted into co2 gas.

3.Metabolism: During the metabolic process, autotrophs will convert the carbon into organic molecules such as fats, carbohydrates, and proteins and these are consumed by the animals.Whereas the heterotrophs-animals consume them and release carbon as the end products of excretion.

4. Oceanic life: There are many oceanic plants, phytoplankton, zooplanktons that prey on each other to consume and release the co2 in different forms.

5. Cellular respiration: This is a very common way of conversion. The animals eat plants to consume organic carbon (carbohydrates) and these organic molecules will be broken down in the body systems during the process of cellular respiration that ultimately releases energy, water, and carbon dioxide. Again this carbon dioxide will be returned to the atmosphere during the gaseous exchange.

6. Precipitation of co2: Co2 Present in the atmosphere gets precipitated into solid carbonates in the ocean sediments.

7. The decay of dead matter: Carbon dioxide is released as a gas into the atmosphere during the decay of all organisms.


 Phosphorus Cycle

Phosphorus is mainly present in its organic form within the body systems. It is also a major component of all biological membranes, nucleic acids, etc. It makes up about 1% of our total body weight. Phosphorus is the second most abundant mineral in our body with the majority being found in the bones and teeth. In addition, phosphorus is a primary component in many bodily processes and cellular energy transfer system. In our nature, the natural reservoir of phosphorus is the rock phosphate. During the weathering process, sunlight and rain act on these rocks to dissolve a small amount of rocky phosphate. This will help in allowing the phosphorus to enter the soil. Soil helps the roots of the plants to absorb them and ultimately the herbivores and other animals obtain their phosphorus by eating these plants. When the plants and animals die, the dead organisms have phosphate-solubilizing bacteria to release phosphorus back into the environment. Phosphorus cannot be converted into gaseous form like oxygen and carbon dioxide.




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