Each year billions of tons of soil are lost worldwide through soil erosion. Erosion reduces soil productivity and deteriorates the quality of our soil and water. The resulting sediment causes stream pollution and reduces the capacity of our reservoirs. Erosion removes the topsoil first, eventually exposing the less productive subsoil. In the most severe cases, eroded land may no longer be fertile and must be abandoned. Soil erosion is a gradual process caused by two forces of nature – wind, and water. In Mexico, chemical dehydration is the dominant soil-degradation process (17,8 % of the country’s area).
Wind erosion occurs when the wind picks up and moves small particles of soil. As wind speeds increase, the amount of soil picked up on a bare field may easily double or even triple. For instance, if a 20mph wind increases to 30mph, the rate of erosion triples.
Water erosion begins with the force of each raindrop. Raindrops may seem insignificant, but they strike the ground with tremendous force. Rain can pound the ground with speeds of up to 30mph. An intense storm of bare soil can loosen and detach up to 100 tons of soil per acre. When raindrops strike the bare ground, they dislodge soil particles and splash them as far as three to five away. This process is greatly exaggerated on a downhill slope. As soil particles are dislodged, they can fill in or plug surface pores in the soil. This prevents water from infiltrating into the ground. Instead of soaking into the ground, the water carries soil particles across the surface, creating erosion. Water erosion can be classified into five types: sheet, rill, ephemeral, gully, and streambank.
Sheet erosion is a subtle type of erosion that can be very damaging over time. It involves the loss of thin, uniform layers of topsoil over the entire field. The soil loss can go almost unnoticed until many years have passed and the subsoil is exposed. By the time you noticed the loss, the damage had already been done.
Rill erosion is easily identified as a series of narrow channels or rills that cut into bare soil. These channels occur on slopes and are small enough to be removed by normal tillage. Rill erosion cannot be predicted and will occur randomly across a hill slope.
Ephemeral erosion differs from rill erosion in that it usually will form in the same location year after year. It develops natural depressions with a concentrated flow of water like rill erosion. It can generally be erased by standard tillage methods.
Gully erosion forms channels that are too large to be erased by ordinary tillage when left unchecked. The top of a gully called the head will continue to cut upslope. Headcut development and gully erosion seriously threaten soil resources and the sustainability of farmlands. Deep wide gullies severely limit land use, making it impossible for farm machinery to cross.
Streambank erosion is caused by the continuous flow of water through a channel, which cuts away the stream bank. It is generally a slow process that can speed up dramatically during floods or heavy rainstorms. Streambank erosion may change the course of a river or creek and causes severe erosion in that specific area.
Erosion Control
Even though erosion is a naturally occurring process, there are ways in which we can decrease its impact on the land. We will provide you with some erosion control methods below. Note that before you start using any of these methods, it is best to first understand the type of erosion occurring on your farmland.
Soil organic matter: Soil organic matter keeps the soil together. It consists of decayed animal and plant remains. According to one research, increasing organic matter in the ground by only 3 percent can significantly reduce soil erosion.
Plant vegetation: the roots of trees hold the soil in place, and their leaves help decrease wind speed. All of these factors significantly reduce water erosion.
Matting: This is a method of erosion control where the ground is covered using leaves. It protects the underlying soil from erosion.
No-till/minimal tillage: Tilling the soil makes it more vulnerable. That is why scientists and experts encourage farmers to use conservational tillage practices.
IPCC report
Scientists are concerned about the increasing rate of soil erosion. This concern was addressed in the UN Intergovernmental Panel on Climate Change. One of their main concerns was the impact soil erosion has on global warming. In the absence of good and healthy soil, plants will not grow. This means that there will be less collection of CO2 from the atmosphere causing the accumulation of greenhouse gases. Also, dry and warm soils attract and keep heat leading to extremely high temperatures and heatwaves. The soil also plays a critical role in the carbon and water cycle. If not taken care of well, it will increase the speed at which climate change occurs.
How to prevent soil erosion in Mexico
Here are some of the ways we can prevent soil erosion:
Revegetate Critical Areas
The plant roots help to keep the ground in place, thereby preventing soil erosion. When planting trees for this purpose, try to use ones native to the particular area. You can also cover the bare soil with leaves and organic matter from trees. This will decrease and prevent the impact of water erosion.
Support Sustainable Agriculture
Farmers try to reduce their activities’ impact on the environment by practicing sustainable agriculture. They do this by minimizing the use of chemical fertilizers and pesticides, no-till/minimum tillage, crop rotation, etc. It helps to maintain soil health and prevent erosion.
For example, Flores Gonzalez developed a revolutionary system of intercropping agave with mesquite trees to produce the world’s cheapest fodder which was also able to sequester “carbon from the air.”
Fight climate change
Another main factor that adds to soil erosion is global warming. It has led to frequent occurring hurricanes, wildfires, and floods, contributing heavily to soil erosion.
Water and wind erosion occur naturally. However, it has been accelerated by many human activities such as farming, deforestation, and construction. All farmers and ranchers should be aware of the potential damage that win, and water can inflict on their land and explore necessary measures to reduce their harmful effects.
