Everywhere we go, we see beautiful plants and animals Earth has given us.
Each organism exists in some kind of balance with other organisms. Plants are the primary source of food for living organisms (herbivores eat plants, carnivores eat herbivores). And, plants usually grow in soil.
It takes soil thousands of years to form. It starts out as a regular rock. The rock goes through weathering (it is broken down). Weathering can be physical, chemical or biological.
Once the rocks have broken down over thousands of years of weathering, it can be seen as being made up of sand, silt and clay.
Sand is the biggest sediment (0.05 mm-2 mm), silt is the second biggest sediment (0.002 mm-0.05 mm), and clay is the smallest sediment (less than 0.002 mm). Porosity (or how many empty spots there are) of the soil depends on the size of the particles. Porosity itself determines the time it will take for water and minerals to travel to the roots of plants.
The ratio of sand to silt to clay determines what kind of soil the soil is. For example, if the type of soil someone is looking at is made up of 25% sand, 45% silt, and 35% clay, it is called clay loam. If it is made up of 30% sand, 60% silt, and 10% clay, it is called silt loam. There are 12 types of soil. Loam is the best type of soil for most plants.
Soil horizons are different layers of soil. The first layer is O, which stands for organics. This layer has most of the decomposed plants — called detritus. The next layer is A, which is also known as topsoil. This is where the surface soil is. This layer is called biomantle because it is where most soil organisms are.
The third layer is B, which is also called subsoil. This has minerals that moved down from the layer above. Layer C (parent material) is where the soil is developed. Layer R (bedrock) is where the rocks (e.g. granite, basalt, quartzite, limestone) form the parent material.
The last layer is E (Eluviated) and it sometimes comes between A and B. This is especially true when the soil is leaching (loss of water-soluble plant materials). This is also where sand and silt are deposited while clay continues further down. Based on its unique compositions, each soil has a specific soil profile.
Because of these layers and formations, soil is classified into 12 soil orders. Entisols are the ones that don’t have any development of soil horizons (recall that a soil horizon is O, A, E, B, C, or R). Entisol is a type of soil that is young and the most common type of soil on Earth. Inceptisol is a type of soil that has a slightly higher soil horizon than entisol. Gelisol is the type of soil that resides at high altitudes in the Arctic and in mountain ranges.
Because it is at such a high altitude, gelisol has permafrost (it’s frozen all throughout the year). And, because of that, it doesn’t move much, which makes its horizon undeveloped.
Spodosol is found in coniferous and boreal forest biomes. The pine needles from these plants fall to the ground and decompose into acidic compounds which gives the soil low fertility.
Alfisol has a fair horizon development and is prevalent in broadleaf and Mediterranean forests. It is rich in iron and aluminum. Ultisol has a lot of iron, which makes it red.
Aridisol is a desert soil and it has the least amount of water. Aridisol is different from the sand found in deserts. Mollisol is dark and is used in agriculture. Oxisol has low soil fertility but its horizon is very well developed.
Andisol is the type of soil found near volcanoes. It is rich in nutrients and overtime, forms beautiful landscapes. Histosol is a wetland soil that is highly acidic because of the build-up of organic matter. And, last but not least, vertisol has high clay content and dries out regularly. The gravels crack and split.
Another way to categorize soil is to do so by looking at it on a chemical level. The type of soil is impacted by factors such as climate, the organisms surrounding it, change in elevation, parent material, and time.
Soil is fundamental in helping human civilizations make food and survive and supporting ecosystems. It is a non-renewable resource which means it is being used faster than it can be replaced. This means that soil must be protected and cherished because it is so important to life.
Vaageesha Das is a 10th grader at Morgantown High School. Today’s information comes from: https://youtu.be/mg7XSjcnZQM; https://youtu.be/BArbrfmsxeQ.
