What is Carbon?
Carbon is a very common element found in minerals like diamonds and graphite, in salts like carbonates, and also in the tissues of all living things. Carbon atoms make up the backbone of all organic compounds. These include sugars, starches, cellulose, fats, proteins and even fossil fuels like oil and coal that formed from plants that grew many millions of years ago.
Organic compounds store a lot of energy in their molecules. We therefore use them as fuels to give us energy (sugars, starches and fats), to keep us warm (wood and coal) or to power our vehicles and industries (oil, petrol and natural gas). We need oxygen to break down organic compounds and liberate the stored energy. This process is called oxidation and includes both respiration and combustion. When organic compounds are oxidised, carbon dioxide gas is produced as a waste product.
Plants absorb carbon dioxide from the air and use the energy of sunlight to convert it into energy-rich organic compounds like carbohydrates. This process, called photosynthesis, ensures that carbon continues to cycle in the environment.
Carbon Dioxide and Climate Change
Carbon dioxide is known as a "greenhouse gas". It is one of the gases that can trap heat in the earth's atmosphere, preventing it from escaping into space. By trapping escaping heat, greenhouse gases help to keep the earth warm. Unfortunately, levels of these gases have been rising steadily since the beginning of the industrial age, since:
As a result of this, the earth is getting warmer and the global climate is changing. In South Africa, we face the prospect of large parts of the country becoming hotter and drier, while other parts will experience more frequent and extreme flooding. Climate change will affect farmers - and we must therefore do all we can to reduce the levels of carbon dioxide in the atmosphere and slow the effects of climate change.
Carbon Sinks - Reversing the Process
Certain agricultural practices have contributed to the increasing levels of carbon dioxide in the atmosphere. However, farmers can also play an important role in helping to reverse this process by "fixing" carbon in plant and animal tissues and by returning organic carbon to the soil. These stores of organic carbon are known as "carbon sinks", because they "drain" carbon dioxide from the atmosphere and hold it for a period in a form that does not contribute to global warming.
Carbon sinks may be relatively temporary or permanent. For example, grasslands are more temporary carbon sinks than forests because the grazing and burning of grasses causes rapid turnover of organic matter. Trees grow more slowly and store organic carbon for many years in woody tissues. However, they too may one day be burned as fuel or die and rot, releasing carbon dioxide into the atmosphere. Soil is the ultimate carbon sink: it contains organic matter derived from plants, animals, fungi and bacteria. About 60% of organic carbon in the soil occurs in a form that binds tightly to clay particles and cannot easily be dislodged. Soil enriched with organic matter is therefore a very stable carbon sink as it can store large amounts of carbon for a very long time.
By managing the land to increase organic carbon in the soil, farmers can fight global climate change and at the same time benefit from richer, more productive soil.
Protect the Vegetation - Revitalise the Soil
Manage the Land to Increase Stored Carbon
Returning organic carbon to the soil is not only good for reducing levels of carbon dioxide in the atmosphere; it also directly benefits agricultural productivity:
Click here to view our fact sheet on carbon sequestration.
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