Soil Erosion

Soil erosion affects both agriculture and the natural environment. Soil loss, and its associated impacts, is one of the most important (yet probably the least well-known) of today's environmental problems. (BBC 2000; Guardian 2004)

"The threat of nuclear weapons and man's ability to destroy the environment are really alarming. And yet there are other almost imperceptible changes - I am thinking of the exhaustion of our natural resources, and especially of soil erosion - and these are perhaps more dangerous still, because once we begin to feel their repercussions it will be too late." (p144 of The Dalai Lama's Little Book of Inner Peace: 2002, Element Books, London)

Those are pretty strong words. Just recently, in my fourth grade class, we were discussing ecosystems and how abiotic (non-living things) are very important to ecosystems. These include sunlight, water, and of course soil. Even fourth graders understand the importance of soil to plants and, consequently, to animals that rely on those plants to survive. We learned that farmers must loosen soil up to plant crops more effectively, but a result of loosening the soil is that the soil can get washed away or blown away easier, making it tough on the insects that live in that soil. But that is not what we’re dealing with when we talk about soil erosion.

A GLASOD study estimated that around 15 per cent of the Earth's ice-free land surface is afflicted by all forms of land degradation. Of this, accelerated soil erosion by water is responsible for about 56 per cent and wind erosion is responsible for about 28 per cent.

The cumulative impact of soil erosion may, over a long timescale, be severe.

Erosion of soil removes the “cream of the soil” or the upper horizon of soil, where the nutrients are rich and the water-holding capacity decreases. This negatively affects the agriculture and the ability to grow good crops. Africa and Asia are dealing with this first hand, but it may also be a concern for more affluent countries in the future.

In addition to its on-site effects, the soil that is detached by accelerated water or wind erosion may be transported considerable distances. This gives rise to 'off-site problems'.

Water erosion’s main off-site effect is the movement of sediment and agricultural pollutants into watercourses. This can lead to the silting-up of dams, disruption of the ecosystems of lakes, and contamination of drinking water. In some cases, increased downstream flooding may also occur due to the reduced capacity of eroded soil to absorb water.

We have known about the dangers of soil erosion for a century and have done much research in the subject.

Erosion is measured and further understood using tools such as the micro-erosion meter (MEM) and the traversing micro-erosion meter (TMEM). The MEM has proved helpful in measuring bedrock erosion in various ecosystems around the world. It can measure both terrestrial and oceanic erosion. On the other hand, the TMEM can be used to track the expanding and contracting of volatile rock formations and can give a reading of how quickly a rock formation is deteriorating.

Tactics for preventing erosion in the future have been under investigation by scientists and geologists all over the world. Today, the most effective method for erosion prevention is soil surface cover. In this method, some type of permeable material, left over crop residue for example, covers the soil surface, which includes rock and sediment debris. This decreases the deteriorating capabilities of the impact from rain, animals, machinery, or any other type of eroding agent. As a result, surface runoff is controlled which helps eliminate the transportation of eroded particles elsewhere, thus slowing the process of erosion as a whole.

Sources: soilerosion.net