A brief history of soil

The first soil

The first microbes on Earth were formed in mats, which are sheets of many microbes. They were built up from photosynthetic organisms that capture sunlight and convert it into energy. These could, and still can, produce huge volumes of organic material using energy from the sun. This organic material gradually built up on shorelines, where it mixed with minerals to create what was arguably the first true soil.

Colonisation of new areas

These tiny microbes that had formed into mat-like structures, at this stage were still single cell organisms. They were unable to travel without help. They were dependent on larger organisms such as lichens to move away and colonise new areas. Both the original organisms and the lichens worked together to colonise soils. The lichens continued to help release nutrients into the soil making it fertile and able to sustain forms of life.

This was the beginning of all life on Earth.

The arrival of plants

Years later, early land plants started to settle within the soil, altering the soil structure further and releasing more nutrients, such as potassium and phosphorus. The symbiotic relationship between the microbes in the soil, including the bacteria, lichens and fungi made the plants more stable by providing a nutritious environment. These plants were then able to colonise the land. Mutualistic relationships such as this form the basis of global nutrient cycling that we see today, a good example being when the vibrant autumn leaves fall and are then decomposed, releasing nutrients down into the soil. 

The arrival of animals

With the arrival of larger animals the soils ecosystem changed again. The early herbivores consumed the organisms such as the lichen and returned the nutrients to the soil through excretion, expulsion and decomposition upon death. Some of these organisms then began burrowing and colonising the soil, mixing up the organic matter with the clays and other minerals within the soil. This gave the soil more structure and helped the plants to thrive from the increased movement of water and nutrients within the soil.

This allowed more varieties of microbes to evolve.

Humans and soil

Human society has developed through utilisation of our planet’s resources, specifically soil and water to produce food and domesticate animals. As humans, we are critically dependent on soil. It is clear that agriculture sustains and defines our modern lives, but it is also crystal clear that our modern way of living has disrupted the soil ecosystem.