The key difference between soil and clay is that soil is a material containing organic matter, minerals, liquids, and organisms, whereas clay is a type of soil that has the property of plasticity upon wetting.
There are six major types of soil named clay, sandy, silty, peaty, chalky, and loamy soil. They have different chemical and physical properties, which makes them useful in different applications.
What is Soil?
Soil is a mixture of organic matter, minerals, gases, liquids, and organisms that supports life. It contains the solid phase of minerals and organic matter and the porous phase that holds gases and water. Therefore, the soil is a 3-state system of solids, liquids, and gases. The factors that affect the formation and properties of soil include climate, reliefs such as elevation and orientation, organisms, and the parent material of the soil. Typically, soil undergoes continuous development via numerous physical, chemical, and biological processes. These processes mainly include weathering and erosion.
Most of the soils have a dry bulk density that lies between 1.1 and 1.6 g/cm3. However, soil particle density is very high and ranges between 2.6 to 2.7 g/cm3. There are four major functions of soil: act as a medium for plants to grow, act as a water storage medium, act as a modifier of the Earth’s atmosphere, and act as a habitat for many organisms.
Generally, soil contains about 50% solid matter, which includes 45% of minerals and 5% of organic matter, and 50% of voids that has pores. These pores are mostly composed of water and gas. When considering a short-term period, the mineral and organic content in soil are constant. However, the percentage of soil water and gas content is highly variable. Moreover, the pore space allows the infiltration of air and water as well as the movement of air and water through them. This infiltration and movement are very important in the existence of life in the soil.
There are numerous uses of the soil, such as the use in agriculture as a primary nutrient base for plants, as a critical component in mining, construction, and landscape development industries, providing critical resources for food and fiber production, preventing floods and droughts by absorbing and releasing water, as a medium for soil microorganisms and other organisms, organic soils’ importance as a significant fuel and horticultural resource, etc.
What is Clay?
Clay is a fine-grained natural soil material that contains clay minerals. Typically, this material develops plasticity when it is wet. This is because of the molecular film of water that surrounds the clay particles. However, it becomes hard, brittle, and non-plastic when drying or firing. Typically, the pure form of clay is white or light-colored. But clay naturally appears in different colors due to the presence of impurities. E.g., reddish or brownish due to trace amounts of iron oxide.
The most well-known property of clay is plasticity upon wetting and the ability to harden when frying or drying. Moreover, clay shows a broad range of water content. Within this range, clay shows high plasticity. The minimum content of water required to mould clay is called the plastic limit. The maximum limit is called the liquid limit. At the liquid limit, clay is slightly dry to hold its shape.
The plasticity of clay comes from clay minerals that give plasticity. Typically, the mineral in the clay is called hydrous aluminum phyllosilicate minerals, which contains aluminum and silicon ions that are bonded to tiny and thin plates that are tough and flexible. Moreover, clay can be found as a common component in sedimentary rocks.
What is the Difference Between Soil and Clay?
Soil is very important for the existence of life on Earth. There are different types of soil, such as clay soil. The key difference between soil and clay is that soil is a material containing organic matter, minerals, liquids, and organisms, whereas clay is a type of soil that has the property of plasticity upon wetting.
The below infographic presents the differences between soil and clay in tabular form for side-by-side comparison.
Summary – Soil vs Clay
Clay is a type of soil. There are many other types of soil, such as sandy soil, loamy soil, chalky soil, etc. The key difference between soil and clay is that soil is a material containing organic matter, minerals, liquids, and organisms, whereas clay is a type of soil that has the property of plasticity upon wetting.
1. “Clay.” McGill School of Computer Science.
1. “Stagnogley” By HolgerK at English Wikipedia – Transferred from en.wikipedia to Commons. (Public Domain) via Commons Wikimedia
2. “Clay-ss-2005” By Siim Sepp – Own work (CC BY-SA 3.0) via Commons Wikimedia