5 Factors That Affect Soil Formation

Soil Formation and What It Provides

Regarding soil, many of us just refer to it as “dirt.” Little do we know, it is this loose material covering the Earth’s surface that is the living, breathing, skin of our planet. Soil supplies plants with the nutrients they need to grow, followed by plants providing humans and animals with nutrient-dense food to consume. It also produces the means for building materials that sustain the living conditions we have grown accustomed to. We rely on it every day and simply would not stand a chance of surviving without it. Vitamins and minerals must exist within the soil for plants to consume them and convert them into nutrient-dense crops for humans to eat.

Soil also provides ecological services such as cleaning groundwater, which will naturally sanitize landscapes and strengthen plant and animal survival. Soil is always forming. But quantity and quality of soil aren’t always a given. We must preserve and protect soil, rather than objectify it. Although it is technically a renewable resource, we should not think of it in this manner.

Soil Forming Processes

Soil formation takes at least hundreds of years to occur – way beyond the typical human lifespan. Although we can rebuild soil in a compost heap, we’re currently polluting the Earth at such a rapid rate that composting cannot compete with. It takes a very long time for physical and chemical processes to occur and for soil-forming factors to work together as one. Soil indeed does not form in a single day; the process can take hundreds, thousands, and even millions of years. Horizon formation, depth, chemical reaction occurrence, vegetative growth, organic matter formation, all take an immense amount of time to come about. Older soils are different than younger soils since the factors have had more time to develop. It may not be the simplest concept to grasp for the impatient, but we cannot deny that time plays a crucial role in soil formation.

Parent Material Affect on Soil Formation

Mineral and Organic

Like humans, soils have parents. Parent material is what is left behind by a soil’s ancestor. It influences the composition, texture, drainage, gas exchange, ability to shrink and swell over time. Also, how quickly a soil may form, the soil biology, type of vegetation that may grow there, deciduous, or evergreen plants growing there, and more. Two kinds of parent materials exist, mineral and organic. Mineral parent material is typically transported by wind, water, or ice (glaciers), while organic parent material is deposited from bodies of water where vegetation had grown on the outside of it and died, resulting in an accumulation of organic material. Parent material determines the inherent properties of soil, as well as the direction and nature of soil development that might occur over time. Bedrock parent material determines what type of soil one may be dealing with.

Soil profile has numerous horizons: O, A, E, B, C. The O Horizon is a mixture of dead vegetation and dying organic material; it is the topsoil in many landscapes. Horizon A is made up of mainly organic matter, passed on from the O Horizon. The E Horizon involves the eluviation of materials from the horizons above, resulting in sand and silt that deposits into Horizon B. The B Horizon has lost most of its minerals from the layers above, while the C Horizon is parent rock and unconsolidated, weathered rock fragments.

Temperature Affect on Soil Formation

Climate will always play a significant role in soil formation, as well. It is the long-term average of conditions a specific area experiences over time. Climate determines the conditions a soil will develop in. Bountiful amounts of rain and heat will produce different vegetation than a dry, cold climate. Weathering rates increase when an environment has a high percentage of precipitation, as well as high temperatures.

Biological Influences

Biological influences such as microorganisms and natural vegetation provide the means for organic matter to form. It emphasizes the importance of a soil’s interactions with flora and fauna. Forests and grasslands are two different types of vegetation. Grasslands are deeper and contain more organic matter but have fewer horizons to look at. Forest have less organic matter but more horizons to look at, highlighting three layers of rock that make up soil: topsoil, subsoil, and bedrock.

Organisms play a significant role in vitalizing nutrients and aggregation, which helps with water retention, drainage, percolation, recycling and other biological processes occurring within the soil. Microbes, nematodes, fungi, myocytes, insects, and small mammals all play a part in decomposition. For example, earthworms contribute to the health of the soil by spending their whole lives eating it and then excreting castings, which are nutritious for plants. After it rains, they travel far underground and create tunnels that create pores within the soil. These pores will then benefit the gas exchange and water movement, strengthening the health of the soil. Farmers even raise worms, just like any other animals, because of how ecologically beneficial they are.

Typography Affect on Soil Formation

The question many ask is, “how does topography affect soil formation”? Topography plays a role in how parent material evolves over time, for it is “the lay of the land.” It is a crucial factor, as it controls the distribution of water within a landscape. Whether it be a valley, a hill, a plateau, a plain, a flat area or a steep area, all of those landforms are considered to be the topography of an area. It greatly affects drainage and the way water flows downhill. Topography influences erosion and generates slope, along with its aspect (a particular direction that a hill is facing). Convex landscapes shed water, while concave landscapes collect water. When water is flowing downhill, it has energy, it can pick up soil particles and transport them from one place to another. When excess water from rainfall is collected at the bottom of a hill, it leads to poor drainage, saturation, and leaching of nutrients. The top of a hill, however, often has better drainage than the bottom due to water flowing downhill (good drainage).

The efficiency of drainage can influence the different properties a soil ends up having. The simplest way to visibly tell the drainage of soil is by observing its color. Well-drained soil reveals red and yellow colors. Poorly drained soil emit dull colors, such as grey and blue, due to differences in physical and chemical reactions. When it comes to texture, three categories concerning soil particle size have been established. Sand has most drainage, largest particle size, feels coarse and gritty, and does not hold onto a lot of water. Silt is smooth when wet, holds on to more water than sands, doesn’t drain as much, and is composed of medium-sized particles. Clay has the smallest particle size, the finest texture, most surface area, is sticky when wet, hard when dry, and aggregates of it pack the most water. But what is the best soil for growing crops? Loam is a mixture of all three and is most ideal for supporting optimal plant growth.

Rich Soils are Essential

Soil is a natural body, a living entity, the foundation of life, and often the answer to countless ecological obstacles. We, as humans, must increase respect for it and focus on developing healthy, nutrient-rich soils to leave behind for future generations. By understanding these five soil-forming factors, one can begin to view the blanket of our planet with more appreciation. Empowering the pedosphere is what will lead us down a more environmentally conscious path in the long run.

As environmental consultants and contractors, the team at Atlantic Environmental hope you enjoyed reading our blog and have gained useful knowledge. If you are in need of environmental services such as soil testing and soil investigationcontact us. We will be happy to assist you.

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