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Soils on earth



Planet Earth - what an amazing place to live! Image: Earth from space, Apollo 17 mission. Copyright and Credit: NASA/Goddard Space Flight Center, Scientific Visualization Studio. Source: http://svs.gsfc.nasa.gov/vis/a000000/a002600/a002681/index.html

The surface of Planet Earth is about 30 per cent land and 70 per cent water - sea, rivers and lakes. It is on the land surface part of the earth that soil forms. Here it plays such a major part in supporting life on earth. The soil is rather like a thin carpet covering the land surface of the planet. Most soils are less than three metres thick. Compare this to the radius of the whole of planet earth which is about 6,000 kilometres and you will quickly appreciate what a very thin skin it is. The thickness of the soil is miniscule compared to the thickness of the earth. Yet as we shall learn this thin layer on the surface of the earth plays a pivotal role in the existence of humans on earth

This very thin skin is a living entity, unlike the very thick rock core below. It contains billions of living organisms which help to form the soil and make it capable of doing marvellous things like produce most of our food, our forests and our wild flowers. We need to appreciate fully the importance of the soil to planet earth and particularly to its growing number of inhabitants.

There are several thousand different types of soil across the surface of planet earth. This is important because it enables us to grow a wide variety of foods and plants in the different climatic areas of the world, varying from dates in desert soils, tropical fruits in the jungle areas, and even in some of the coldest areas of the world, as soon as summer comes shrubs and grasses to feed grazing animals appear from the soil. We should appreciate the part soil plays in all our lives!