SOIL FEATURES
Soil, which is vital to life on Earth and is the basic factor of every farming activity, develops slowly over time.
ONLINE RESOURCES
- Shale gas
Soil composition1
The basic components of soil are minerals, organic matter, water and air. Typical soil consists of:
- a solid part: 45% mineral and 5% organic matter;
- a liquid and a gas part: 20- 30% water and 20-30% air.
These percentages are only generalisations at best because soil is very complex and dynamic.
While soil minerals and organic matter hold and store nutrients, soil water is what readily provides nutrients for plant uptake. Soil air, too, plays an integral role since many of the microorganisms that live in the soil need air to carry out the biological processes that release additional nutrients into the soil.
As a matter of fact, there is an incredible diversity of organisms that live out and complete their life cycle below ground level. This community of living micro-organisms and organisms is called the soil food web and is made up of one-celled bacteria, algae, fungi, protozoa, nematodes, micro-arthropods, earthworms, insects, small vertebrates, and plants.
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1 Do you think soil composition is basically the same in any location?
The role of soils
There are five general roles that soils play. Soils:
- serve as a means for growth of all kinds of plants;
- modify the atmosphere by emitting and absorbing gases (carbon dioxide, methane, water vapour) and dust;
- provide habitat for animals that live in the soil (such as moles and mice) and for organisms such as bacteria and fungi;
- absorb, hold, release and purify most of the water in terrestrial systems;
- process recycled nutrients, including carbon, so that living things can use them over and over again.
Stable, healthy and productive soils are essential for producing most of our food, and for maintaining environmental functions, managing water quality, sustaining our primary industries and supporting rural and urban communities.1
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SDG 15 Life on Land: Protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss.