Soil erosion is one of the most important threats facing our planet today. Fertile soil is the delicate membrane upon which agriculture and the growth of all plant life on the face of the planet depend. This covering is today under threat due to the activities of man, as well as changing weather conditions. Heavy agricultural land use, as well as weather conditions can strip away this delicate layer of productive soil. Once it is gone it can take hundreds of years to build up again due to the fact that organic material is required to return the soil to a condition where it can support plant life.
According the the World Wildlife Fund the last 150 years has seen approximately 50% of the world’s topsoil disappear.
One of the reasons that soil erosion is becoming an increasing problem is that agricultural crops are increasingly replacing naturally occurring plant species. Once the natural vegetation disappears the shallow root systems of agricultural crops cannot anchor productive soil to the non productive substrate and it simply washes away.
This is increasingly a problem in areas where slash and burn agriculture is a way of life, such as in Southeast Asia and South America. In this approach to growing crops vast swathes of land (often primary jungle) is burned to make way for either subsidence crops or in Southeast Asia palm plantations. The burning provides nutrients that support the crops, however these nutrients are usually exhausted after a single growing season.
In the case subsidence crops in South America the farmer simply moves on to the next area and engages in slash and burn agricultural practices again. The area left behind has no plant life and what remains of the soil is eroded through the actions of wind, rain and running water.
In cases like this the land takes decades to recover and in most cases primary forest is replaced by secondary forest and that area of biological diversity never regains its former glory.
In places where forest and plant life have been denuded the soil is easily washed away. In the absence of root systems water is not held in the ground. The result can be flash floods and landslides. The result is dangerous to human beings and once the process begins it tends to accelerate as more and more topsoil is washed away.
The absence of plants to bind topsoil together means that rivers in areas where topsoil is exposed quickly become muddy and filled with silt. That has numerous effects on both wildlife and the societies that rely on these rivers and streams for clean drinking water. The result of this topsoil runoff can include increased levels of waterborne disease, as well as a die off of organisms in the affected rivers. As many people rely on these organisms for food the results are nothing short of catastrophic.
As weather patterns continue to change the effects of soil erosion are becoming more pronounced across the world.The annual monsoon rains that affect Asia and much of Southeast Asia are now causing flooding on a scale that has not been seen before. Without plants that rely on topsoil to grow and bind the earth, absorbing groundwater these annual events are now threatening the lives of more people than ever before. With flooding comes disease and the loss of livestock upon which many of these communities rely.
If we do not start paying attention to soil erosion caused by human activity the number of man made disasters will continue to grow. Topsoil, once lost, is tremendously difficult to replace. The clock is ticking and we, as a species are running out of time to address this issue.