Soil is extremely important as a filter removing pollution from our drinking water and helping to regulate the flow of water through the landscape. Most rainwater ends up moving into the soil before it gets to plant roots, the aquifers or the river!
Soil is also the foundation for our buildings and roads. Houses and schools are built on soil. The type of soil affects how buildings are made!
Soil also protects our history and past - archaeological finds are dug from the soil. Soil plays an important part in the preservation of the earth's history.
Finally, soils are important in the story of climate change. Soil organic matter is one of the major pools of carbon in the biosphere and is important both as a driver of climatic change and as a response variable to climate change, capable of acting both as a source and sink of carbon. Soils also helps regulate other greenhouse gases such as nitrous oxide and methane.
The Millennium Ecosystem Assessment (MA) produced in the early 2000s identified 'ecosystem services' as the benefits that people obtain from ecosystems, including provisioning services such as food, water, timber, and fiber; regulating services that affect climate, foods, disease, wastes, and water quality; cultural services that provide recreational, aesthetic, and spiritual benefits; and supporting services such as soil formation, photosynthesis, and nutrient cycling. Humans, while buffered against environmental changes by culture and technology, are fundamentally dependent on the flow of these ecosystem services.
Many of these 'ecosystem services' depend on the functioning of soil - from regulating flood waters, to supporting agriculture and from recreation activities to nutrient recycling. This section identifies the many and varied soil functions.
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!
There is a strong dependence on our world soils. We have shown in the Soil Functions section that the soil provides many functions. It provides for our food, whether on the farm or in the garden; much of our wildlife including the wonderful array of wild flowers and trees; it is the home for a remarkable array of organisms, including many we have yet to discover; it stores and filters water which eventually becomes our drinking water; it provides a foundation for our towns and villages, and has done this since humans first appeared on earth; and last but not least it is an important key to global well-being.
Linking healthy soil, crops and people
The world population is currently increasing at a fast rate. It has gone from about 1 billion people in 1800, to 3 billion by 1960, to 6 billion by 2000 and is expected to reach 9 billion by 2050. All these people will be relying on the soil to provide all those useful functions mentioned above and ultimately for their survival. This means that we need to look after our soils to ensure that they can support this growing population.
Already in the last 50 years there has been increasing evidence of mismanagement of our soils. Whether through ignorance or through mismanagement of the land, there is abundant evidence of damage to this precious resource worldwide. Soil erosion and desertification is widespread and affecting millions of hectares of land. Desertification and salinisation are causing major problems in the drier parts of the world. Pollution either directly to the soil or by way of acid rain from the atmosphere is a problem in some areas, not only affecting the soil but leaving the soil to cause pollution to water bodies and loss of aquatic life. Intensive farming, while producing increasing crop yields to feed the growing population, has put increasing pressure on the soil and this has led to soil degradation. It is more and more important that we understand the pressures that we are putting on our soils and take steps to safeguard them as we go into the future. This Section describes some of the threats to our soils, how we can deal them and how important it is that there is a global approach to managing our soils for future generations.
