Appreciating the Water-Soil relationship - World Soil Day 2020
“Keep soil alive, protect soil biodiversity”, is the theme for this year’s World Soil Day which we’ll be celebrating today. But what does soil biodiversity have to do with water? It turns out that they are pretty much connected.
Right beneath our feet is a whole community composed of megafauna, macrofauna, mesofauna, microfauna, and microorganisms working closely with each other. This delicate ecosystem is responsible for a variety of important processes. These soil organisms are involved in the processing of organic waste matter, regulation of carbon flux, and the cycling of water. They work the sand, clay, or silt, their activities are responsible for the creation of structures and habitats in the soil that aerate it and allow the water to permeate through it. For example, earthworms are capable of tunneling through the soil. Because of this, they make the soil more effective at soaking up water. Moreover, there are soil organisms that help bind the soil particles together. As a bonus, the soil organisms enable the soil to store and release carbon and regulate the flux of greenhouse gases, which ultimately helps with climate change. This positive change in climate would be beneficial to the availability of water in the long run.
Good Soil can Store and Purify Water
The soil acts as a kind of filter. As water goes through the tiny spaces in between the soil, contaminants like bacteria and viruses can get lodged in these spaces. Essentially, the water is stripped off of its contaminants. This capability to purify water is enhanced further when the soil is rich in microorganisms. Earthworms, ants, termites, and other organisms that burrow and tunnel through the soil can create channels, nests, and galleries that can help capture water. Leaf litter and root systems from vegetation also keep water in the soil without necessarily washing them away. Without the soil organisms and the vegetation, the soil becomes weak and gets easily eroded. Aside from that, the soil’s ability to absorb and cleanse water is compromised and groundwater would be negatively affected.
What Happens When Good Soil isn’t kept?
The ecosystem that exists beneath our feet isn't exactly indestructible. Structures within the soil that are created by the activity of the soil organisms can be destroyed by human activities especially those that use heavy machinery. Once the structures are destroyed by the weight, the activities of the soil organisms are disrupted and the soil becomes less aerated. What’s more, is that the organisms could actually die from soil compaction.
After soil compaction, ‘sealing’ could occur. The soil becomes so compacted that they become impermeable to water and air. Essentially, the space beneath the impermeable layer suffocates and any microorganism dependent on oxygen that is present there would die. Urbanization and the use of concrete and asphalt could all contribute to sealing. Once the soil becomes ‘sealed’, when the rain comes they wouldn’t be able to absorb the rain, and flooding and erosion are more likely to occur.
At some point, when the soil’s damage is irreversible, desertification could occur. From the word itself, the soil becomes desert-like. Plants do not grow when desertification occurs and the soil is easily eroded by air or water. When the top is completely eroded away, desertification reaches the point of no return.
The soil and its ecosystem have a close relationship with water. If the soil is good, it could store and even purify water. However, when the soil is in a bad condition such as in soil compaction, sealing, and desertification, they become an environmental hazard as they could encourage flooding, owing to their inability to absorb water.