Is soil really in danger of running out?
- About 60 years of topsoil left
- Some 40% of soil used for agriculture around the world is degraded or seriously degraded
- 70% of the topsoil, the layer allowing plants to grow, is gone
Decline in worldwide the amount of cropland per capita
How does soil erosion happen?
- Overexploitation for fuel wood
- Agricultural activities and industrialization
The above figure illustrates the relative sizes of the causal mechanisms as a function of region.
What happens if this isn’t addressed?
- One is the loss of soil productivity:
We will produce 30% less food over the next 20-50 years
- Second is that water will reach a crisis point:
Even moderately degraded soil will hold less a half of the water than
healthy soil does in the same location
Who will be impacted the most?
No continent is free from the problem. Areas of serious concern include zones where up to 75% of the topsoil has been lost already. The central portion of the United States is an area of particular local concern. Soil erosion is most serious in China, India and parts of South America. If the food supply goes down, then obviously, the price goes up. The crisis point will hit the poorest countries hardest, in particular those who rely on imports. The capacity of the planet to produce food is already causing conflict.
Of the world’s 1.2 billion hectares with moderate to severe soil degradation, the largest areas are in Asia and Africa. Central America has the highest percentage and worst degrees of soil degradation
What is Topsoil?
Topsoil is the upper layer of soil that contains most of the available plant nutrients and in which most of the biological activity takes place. The soil’s organic matter is concentrated in the topsoil, making it noticeably darker than the subsoil. The topsoil is the primary home of the vast “soil food web”—the amazingly complex community of microorganisms, earthworms, insects, and small vertebrates that is the only proper home for the roots of crop plants.
A soil profile is the side view of soil, from the uppermost layer to the bottom layer.
- The topmost layer of the soil is composed mainly of fresh soil and decaying organic matter. The color ranges from brown to black.
- The second layer of the soil consists of highly decomposing organic matter. The color ranges from brown to gray.
- The third layer of soil is composed of sand and silt. It has lost most of its nutrients. The color of this layer is light brown.
- The fourth layer consists of clay and large rocks and bedrock. The color ranges from rust to tan.
- The fifth layer of soil is bedrock. The color is gray.
Why is Soil So Important?
Soil is more than just the dirt under our feet. It is a home for living organisms and it provides nutrients and stability for plants to grow. Without soil, the plants necessary for people and animals to survive could not exist. By caring for our soil properly, we can ensure the longevity of both animals and people. The use of crop rotation, limiting harsh chemicals and composting will help to maintain a healthy balance of nutrients, living organisms and minerals in the soil. It is important to remember that the fresh foods on which we feast affect our health. To the question, “Why is soil so important”, the simple answer is that we are what we eat.