Reducing Soil Erosion: Mushrooms vs. Plants"

 Background Research 

Soil erosion is the process in which the top layers of the land are moved or worn away and can be a naturally occurring process, or caused by humans. When it comes to soil erosion, the term ‘naturally occurring’ just means that the soil is worn away in healthy amounts and not caused by stress on the land. Natural soil erosion is caused by water, wind, ice, or gravity. Humans caused soil erosion is the result of harmful farming/agricultural practices, deforestation, and mining (LumenLearning). 

Naturally occurring soil erosion can be beneficial to the environments’ health. In the matter of benefiting the environment, soil erosion can be compared to naturally occurring forest fires. The fires burn away decaying or dead matter, which allows the nutrients to return to the soil. It also acts as a disinfectant, removing disease-ridden plants and harmful insects from the ecosystem. Soil erosion, as a natural and healthy case, can do a similar job. Natural soil erosion can help clean the soil of rotting plant matter or nutrient-less dirt from the area. With the nutrient-less dirt gone, future plants can thrive on the new, nutrient-rich soil. 

However, soil erosion can also cause a lot of damage to the environment. The top layers of soil are where most of the nutrients are stored. If these top layers are eroded away while there are still nutrients in the soil, then future generations of plant life and growth will be stunted. In the case of water erosion, especially when cropland is involved, the soil washed away most likely contains hazardous chemicals such as pesticides or fertilizers. If the washed away soil enters a local water supply, then it poses a threat to the health of citizens in the area. If the washed away soil enters any body of water with aquatic life, then their health is also threatened by the presence of chemical infused soil entering the water. The last thing (once again specifically in the case of water erosion) is if the eroded areas aren’t tended to and water continues to run along the already eroded soil, there are chances of the land and any nearby populations suffering from flash-flood damages (Tucker, 2018). 

Recent data collected from The Economics of Land Degradation and UNCCD (United Nations Convention to Combat Desertification) in 2015 have concluded that: 

• It’s estimated that the soil lost to soil erosion is 24 billion tons per year. 

• On a global scale, 10-20% of the land degraded (as a result of erosion) are drylands and 24% are farmlands. 

• 40% of the world’s degraded lands are in areas where the poverty rates are high. 

• The livelihood and health of 1.5 billion people in the world are affected by the damages caused by soil erosion. 

• Specifically in the US, it costs $490 billion to pay for the damages caused by soil erosion. Depending on where the damage is and what the damage is, it can cost even more to bring in equipment in an attempt to repair the damages. 

• 55% of soil erosion is caused by water.

The reason that soil erosion is so detrimental is that the rates of soil erosion are high while the recovery rates are very low. It takes 500 years for 2.5cm of topsoil to form again. Even for that, the soil has to be kept in protected conditions, away from what could cause soil erosion and harmful farming practices (Soil Erosion, 2015). 

Since 55% of the soil erosion on Earth is caused by water, that will be the main focus. While water erosion can technically happen in any area that has rainfall or any body of water near it, specific factors that affect the rates and magnitude of the damage are: Rainfall & Runoff, Soil Erodibility, Slope Gradient & Length, Cropping & Vegetation, and Tillage Practices. Rainfall & Runoff (when excess stormwater, meltwater, or other sources flow over the Earth's surface) is when the duration of storms are long and the intensity is high. Soil Erodibility is an estimate of how resistant the soil in the area is to soil erosion. Slope Gradient & Length is, basically, how soil erosion is most common on steeper and longer slopes on a field. Cropping & Vegetation is when there are either a lot of plants covering the surface of the area or not plants. Having more plants covering an area of land makes the chances of erosion less high. Finally, Tillage practices are a reference to harmful farming practices, specifically plowing. Generally, the fewer disturbances there are to vegetation or overall plant life on the surface, the more effective the tillage practice is at reducing water-caused soil erosion. When it comes to water caused erosion, there are four types of erosion: Sheet Erosion, Rill Erosion, Gully Erosion, and Bank Erosion. 

• Sheet Erosion is the result of raindrops coming down too harshly onto the ground and runoff water. It tends to occur evenly over a uniform slope and isn’t noticeable until it’s too late, when the topsoil is lost. The eroded soil is deposited in low areas, and indicators one could use to detect Sheet Erosion are: lighter colored soils on knolls, changes in soil horizon thickness, and low crop fields on shoulder slopes and knolls. 

• Rill Erosion is when surface water runoff concentrates and forms small, yet well-defined channels. The channels where the soil has been washed away are called rills, hence the name Rill Erosion. This type of erosion isn’t too damaging to the point where it interferes with field machinery or operation when it comes to farm work, and in many cases, rills are filled each year due to tillage operations. 

• Gully Erosion is an advanced stage of Rill Erosion and it’s when the surface channels are eroded to the point where they do interfere with tillage operations. They are typically caused by improper outlet designs for local surface or subsurface drainage systems. They lead to the sloughing (shredding/casting off) and slumping (caving in) of bank slopes, which in turn leads to the land being taken out of production. The lands are no longer safe for farming due to hazardous conditions.

• Bank Erosion is the undercutting, scouring, and slumping of drainage ways that are used as outlets for surface water runoff. These drainage ways are generally just natural streams or, in some cases, constructed channels. The cause for the actual erosion is a combination of poor construction, inadequate maintenance, uncontrolled livestock (overgrazing and trampling over the land), and cropping too close to the surface. 

The direct damage of all water caused soil erosion is the loss of farmland and the undermining of certain structures, like bridges (Ritter, 2012). 

Plants are known to be a popular solution when it comes to helping reduce soil erosion. The reasons are because they cover the soil surface and have roots. Leaves and branches help shield the topsoil from direct contact with water or wind. The root system that plants have help bind the soil together and keep the soil down. It helps in the case that any water makes it past or the branches or leaves, and it’s a natural defense against runoff water (Beaulieu, 2019). 

Mushrooms have the potential of doing what plants do when it comes to reducing soil erosion. Most species of mushroom have disc-shaped tops, which can block the raindrops from making direct contact with the soil. Though mushrooms don’t have a root system like plants do, they do have a root-like structure that’s hidden underground. This structure is known as Mycelium, and it’s the vegetative part of fungi that consists of a network of fine white filaments called Hyphae. Mycelium can not only bind the soil and hold it in place (like plant roots can), but it can also release CO2 into the atmosphere and add nutrients to the surrounding soil. Generally speaking, mushrooms don’t only have the potential of helping to reduce soil erosion, mushrooms can also help give back nutrients to the ground and surrounding plants (Crystal, 2018).