Question: What are nutrient cycles and carbon cycles?

Emma Markham answered on 19 Jun 2019: last edited 20 Jun 2019 7:45 am

That’s a great question. So, like the law of the conservation of energy in physics, where energy cannot be created or destroyed but it can be transformed into different forms, or the water cycle where water evaporates, condenses in clouds, comes back to earth in the form of rain and can then evaporate again, it just goes round and round.
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The carbon cycle is really fascinating because it plays a big role in climate change at the moment, and so you will hear a lot of projects in the news about ‘being carbon neutral’ and ‘carbon capture’ so what is the carbon cycle?
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Carbon is a key component of all life on earth, this is why we are called carbon-based lifeforms, because all organisms contain carbon. When the plants and animals containing carbon die most of the carbon goes into the earth, where it can be compressed into diamonds, coal or crude oil if the conditions are right, otherwise it can form the soil and other animals can eat the nutrients and the carbon becomes part of these animals. Peat is where lots of plants died in a bog or very wet conditions, so they could not be broken down in the normal way, this has a lot of stored energy and carbon, but this is released if we burn it. This is why people are concerned about the removal of peat, because it acts as an excellent carbon store. So if you burn peat, coal or fossil fuels you are releasing the stored carbon into the atmosphere in the form of CO2.
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We need some CO2 in the atmostphere, because it acts as a blanket helping the earth regulate it’s temperature (If a planet doesn’t have an atmostphere then it gets extremely hot in the day and extremely cold at night), and the CO2 is also important because plants need this for photosynthesis, so they can make sugars and get energy from the sun. The main problem is that we are burning more fossil fuels and releasing more CO2 into the atmostphere and there are not enough plants to keep removing it from the atmosphere. So that blanket is trapping too much heat in the earth’s atmosphere causing global warming. Scientists are looking at growing plants which are good at removing lots of CO2, but the challenge is storing it. Trees are a great store of carbon but take a long time to grow and you cannot burn the wood, because it was just release the carbon back into the atmostphere. So it’s a really challenge for scientist to find a way to remove carbon from the atomosphere. One aim is to produce less carbon, by limiting the use of burning fossil fuels and instead using renewable energy.
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Nutrients are cycled in the same way, we contain lots of other elements and when we die those elements still exist and need to cycle round again, because you cannot create an element and there is only a limited about of each on earth. One interesting nutrient is Nitrogen, this is normally found in the air but is also really important to all living things, so we cannot get nitrogen directly from the air but need to get to through our food. Some plants have special bacteria in their roots which ‘fix’ the nitrogen in the air into another form which the plant can then use to grow, we can get nitrogen by eating the plant or by eating an animal which ate plants. some of the nitrogen is excreted but a lot of it is used to make the plants and animals where it is stored, and then when an plant or animal dies bacteria will recycle this nitrogen back into the air. it goes round and round.