Posted: February 1st, 2023

Components of the Soil or Soil Microorganisms

Mineral Components: The soil’s mineral components are extracted either from the parental rocks or from the regoliths. They can be present as particles of varying sizes, ranging from clay that has a diameter of 0.0002 mm or less to large pebbles and stones. The minerals account for about 90 percent of the soil’s overall weight. Oxygen, Si, Fe, Al, N,P, K, Ca, Mg, C, H, and so on are the essential elements that are present in the compound state. Nitrogen originates from the environment in the form of nitrogen salts in the soil.

Organic Matter or Humus: In addition to inorganic minerals, certain organic remnants are found in the soil, obtained from either dead plants or remains of an animal or the metabolic processes of living organisms. When plants and animals expire, a variety of microorganisms acts on their dead remains and eventually decays or decomposes them into simple organic compounds. Humus, a dark-colored, jelly-like amorphous material consisting of residual organic matter that is not readily decomposed by soil microorganisms, is a result of this microbial decay. The humus-forming phase is called humification. Carbon, hydrogen, oxygen, sulfur, and nitrogen are the main elements present in humus. Carbohydrates, phosphoric acid, certain organic acids, fats, resins, urea, and so on are the essential compounds found in humus.

Soil Atmosphere: Gases found in soil are said to create the soil atmosphere, which is one of the most important elements of the soil. The spaces between soil particles and organisms in the soil are called pore spaces. They are packed with differing levels of air and moisture, accounting for about half of the overall soil content. The level of moisture in dry soils is less when compared to humid soils. There are three primary gases present in the soil atmosphere; they are oxygen, carbon dioxide, and nitrogen. Oxygen is 20 percent in the soil atmosphere, nitrogen is about 79 percent, and carbon dioxide is present in 0.15 to 0.65 percent in volume. The CO2 percentage in agricultural soils is significantly higher than that of ambient CO2, but the content of oxygen in those soils is less when compared to the percentage of atmospheric oxygen.

Soil Water: Soil water has a very crucial part in the development of plants. A small amount of ram water and dew is directly absorbed by plants from their surfaces, but much of the water they consume is from the soil. The texture, composition, and soil particle’s compactness are preserved by the soil water. It is a strong solvent for minerals which decreases nutrient concentration so that the nutrients can be readily consumed by plants. Water comes in the soil predominantly from the infiltration and irrigation of precipitated water such as rain, snow, and hail, although it is mostly lost from the soil by evaporation, streamflow percolation, and transpiration. The amount of water in the soil that is available ranges among places. The amount also depends on the soil condition. The amount of water in loamy, silty, and clay soils is more when compared to coarse sandy soil.

Biological components of the Soil or Soil Microorganisms:
Organisms present in the soil are known as soil organisms. Many of these species in the soil are stationary, some are mobile, but others are retained in the soil particles’ colloidal films. Examples of moving life include protozoans, mites, and insects. In pursuit of food, they travel inside or remain on the surface of the soil. The burrowing habit of earthworms loosens the soil making them fertile. In an acidic soil environment, most soil fungi are found. Actinomycetes are found in saline soils, and in neutral soils that are high in organic nutrients, soil bacteria expand reasonably well. Under conditions of continuous shade and moisture, algae are present in the topmost layer of the soil.

The texture of soil:
Several particles that range in size make up the texture of the soil. Soils can be gritty, sandy with differing amounts of organic matter, depending on their textures. The soil fragments are often exceedingly small and achieve the characteristics of colloids. The clay component of the soil constitutes these particles. The soil particles are categorized into three groups such as sand, silt, and clay-based on their sizes. If all the three particles are present in similar proportions, the soil is loamy. Particles of sand are small pieces of a rock that do not interact intensely with rocks or water. Smooth or irregular, covered with dirt, are the textures of silt particles. These have their properties between sand and clay form. Sandy soils make the percolation and evaporation of water easier, while clay soils hold water strongly. The soil’s water retaining potential is impaired by the volume and the presence of organic material.