Lesson 45: Soil Degradation
In this lesson,
we will be looking at soil degradation and the loss of topsoil. We will also
look at how agriculture and mining are the two biggest activities that affect
soil around the world.
Soil degradation occurs when key soil attributes for plant growth or ecosystem
functionality deteriorate.
To combat this, the United Nations funded a project to produce a global view of
soil quality called Global Assessment of Land Degradation and Improvement
(GLADA). Through the research conducted by GLADA, the UN was able to identify
areas in the world that were improving or worsening.
One of the key areas looked at was topsoil. Topsoil is lost through erosion.
This can happen when vegetative cover is removed. Eroding soil is called
sediment. Topsoil erosion can destroy habitats. Water erosion can change soil
composition over time, leading to hardening of the soil and dryness and
creating a crust that stops further erosion but also prevents water from
passing through or seeds from taking root.
Soils are most affected by agriculture and mining. Some agricultural practices
such as center-pivot irrigation, drip irrigation and no-till agriculture have
met with great success in terms of maintaining topsoil. However, they come with
side effects such as salinization where there are too many salts in the soil
and plant growth is suppressed, and leaching where soils lose nutrients that
flow right out of the soil.
Mining is big business. Mining involves pulling out metals, salts and other
materials out of the earth to make goods and services. Mining removes
vegetation and impacts human health, water quality and results in soil erosion.