Types of Soil - Sandy, Silty, Clay, Peaty, Saline and Loam Soil
The soil is defined as the organic and inorganic materials on the earth surface which provides the medium for growth of the plants. It slowly develops over time and it is composed of various different materials and it varies due to its composition and structure. It is important for the sustainability of an ecosystem as it serves as the natural medium for the vegetation growth. Soil comes under the non- renewable resources and its formation is a very slow process.
Soil Profile and Soil Horizons:
The soil profile is somewhat similar to that of the soil's fingerprint. It will differ from other soil samples based on the factors like texture, structure, color, and thickness including its chemical composition.
Each layer’s soil profile is referred to as the soil horizon and these horizons can be identified by letters. The upper and the topmost layer of the soil which is the topsoil that we walk on is the Horizon “O”. it is made up of decayed organic stuff which feeds the soil and keeps it healthy and it is one- inch thick. This topmost layer of the soil is said to be the most productive layer and the most fertile part of the soil. This is because it contains busy microorganisms and good hummus that will make the nutrients to be available for the plants.
Horizon “O” will be followed by the Horizon “A” which is the next layer of the soil. It is composed of beneficial microorganisms like mycorrhizae and fungi, composed of roots and it is also a part of the topsoil. The microorganisms will feed on the waste materials and shed off by roots. This layer is said to be the home for earthworms and centipede which are critters.
Next layer will be the Horizon “B” which is said to be the tough layer and this soil is hard that roots or critters cannot penetrate this barrier.
Horizon “C” is the next layer, which is the parent material where old soil and rocks that form all the horizons above it. Horizon “C” layer consists of primary bedrock and secondary materials from other places.
Soil Composition and Formation:
The soil is a composition of small pieces of fallen leaves, decomposed tree branches, decayed plants, pieces of broken rock etc. it is said that the soil stores 0.01% of the total water on Earth surface within its nooks, pores, and crannies. Soil contains the following composition:
• 5% organic matter
• 25% air
• 25% of water
• 45% of minerals
An acre of soil can hold nearly 5- 10 tons of living organisms and another interesting fact is that one measly gram of soil will hold about 5000- 7000 bacteria species.
Since the soil is composed of different materials and composition, it affects its formation, colors, and textures too. The soil can be found in colors like yellow, red and white but most common colors are brown, black and grey. The soil could be smooth, rough, creamy, rough, sticky and crumbly to touch due to the presence of silt, sand, clay and other mineral particles.
Soil takes about 500 years in order to create just an inch of the top layer. Weathering, rains, erosions, floods, thunderstorms, hurricanes, tornadoes etc which are the natural processes contribute to the formation of the soil.
Types of soil:
Soil can be categorized into sandy soil, silty soil, clay soil, peaty soil, saline soil, and loam soil. Following are the classifications
1. Sandy soil:
Among the different types of soil, sandy soil has the largest particles in it. It feels gritty and dry when touched and this is due to the huge spaces present between the particles and also it will not be able to hold water. Rapidly water drains directly to the places where the roots, especially to those seedlings cannot reach. Since they are carried away by the runoff, plants don’t have a chance of using the nutrients present in this soil efficiently. During the spring season, the top side of the sandy soil which is light to work with and also warms quickly.
Moistening the soil and rolling it into a ball in order to check the predominating soil particle is the methods used for testing the soil type. Wet sandy soil when rolled on our palms, there should be no ball formation and it will crumble through our fingers easily.
2. Silty soil:
When compared to sandy soil, silty soil will be smaller in size and so it will be smoother and it becomes soapy slick when moistened. Silty soil, when rolled between fingers, it leaves dirt on our skin.
Even though this soil is fertile, it can't hold as many nutrients but it can retain water for a longer period of time. It is cold in nature because of its moisture- retention quality and also it can get compacted easily.
3. Clay soil:
When compared to the above-mentioned soils, clay soil has the smallest particles composition and it has fair water storage qualities. Only a little air can pass through its spaces because of the tiny size of its particles and its tendency to settle together. Plant nutrients will be tightly held due to its slower draining tendency and so this soil is rich in plant food for better growth.
During spring, this soil is cold and it will take time to get warm as the water within the soil should also get warmed. When it gets dry, the downside of the soil will be very heavy to work with. Also, it could turn hard and compact during the summer seasons. It feels sticky, rolls up easily and forms into a sausage- like Shape if moistened.
4. Peaty soil:
The color of the peaty soil will be black or dark brown in color. It can be compressed easily due to the presence of high water content in it and feels soft when touched and it is also rich in organic matter. This soil growers use it to regulate the pH levels or soil chemistry as an agent to control the disease for the soil and it also contains acidic water.
There will be no ball formation when peat soil is rolled in our palms and when squeezed the water content will be forced out. When touched, this soil will be spongy in nature. peaty soli can produce good rice crops when drained and fertilized properly.
5. Saline soil:
In extremely dry conditions, this soil will usually be brackish due to its high salt content. Saline soil can cause damage and even stall plant growth, cause difficulties in irrigation and impede germination. The reason for this soil’s salinity is due to the soluble salts buildup in the rhizosphere. The water uptake by the plants is prevented due to high salt contents and thus leading to drought stress. The easy way to find a saline soil is, it would form a white layer coating the surface of the soil and plants grow poorly, they will suffer leaf tip burn which can be especially seen in young leaves.
6. Loam soil:
Loam soil is said to be the ideal type of soil as the gardens and gardeners just love it. The three materials like silt, clay plus hummus and sand are balanced present in this soil. Due to its previous organic matter content, it will have higher calcium and pH levels.
The color of this soil is dark and it is dry and crumbles when touched. Between the soil particles, the air moves freely down to the roots.
How to find out the type of soil in your garden?
In order to find out the type of soil without getting your hands dirty, just fill the soil sample in a jar, shake vigorously and allow the soil to settle overnight. The very next day, distinct layers of the soil can be seen. Clay will remain at the top, followed by silt and then sand at the bottom layer.
Soil Erosion and Resistance to Erosion:
By the actions of flowing water, the force of gravity, ice or wind, the soil profiles will be continuously disrupted. The soil particles from “A” horizons are removed and expose the horizons’ subsurface to weathering, plant nutrients, resulting in the humus loss and beneficial to the organisms of the soil.
Depending upon the texture and topographic characteristics of the soil, lies the soil’s ability to resist wind and water erosion. Due to the strong cohesive forces between the particles and the glue-like characteristics of the hummus, the clay-rich soil can resist erosion. Loam soil has sufficient clay content in order to hold the particles together and sandy soils have high permeability limits so both the soils are moderately resistant. Due to the low permeability value, the silty soils can exhibit the least resistance to soil erosion.
Deposition of soil and erosion of soil are the natural geomorphic process which gives shapes to the landforms and in order for the development of soil profiles, it provides new parent material. Knowledge of actual and acceptable rates of soil erosion is required for the development of soil conservation.