The soil particles are divided into three groups according to their size. Sand, silt, and clay are the three groups. However the largest group is sand and the smallest one is clay.
SOIL
Soil is the upper unconsolidated portion of the earth’s crust consisting of organic and inorganic material that serves as a natural medium for the growth of land plants.
PHYSICAL PROPERTIES OF SOIL
The physical properties of the soil are related to the size and structure of soil particles and the impact of transporting fluids and gasses through the soils. Therefore the weathering of rocks and minerals creates soil mineral particles.
Soil Texture
Most of the soils are a mixture of all these three groups. The relative percentage of sand, silt, and clay determine the texture of the soil. For instance, soil with a clayey loam texture contains roughly equal parts of sand, silt, and clay. Therefore these textural separations are the result of the aging process. On the soil texture triangle, there are 12 textural classes of the soil. Every texture refers to a particular percentage of sand, silt, or clay. An awareness of the texture aids us in soil conservation.
Soil Structure
The arrangement of soil particles in small groups known as peds or aggregates. The structure of particles could be granular, blocky, columnar, platy, massive, or single-grain. Therefore the soil pores control the root growth, air and water movement
Soil Colour
Colour of soil also tells us what is present in a particular soil. However iron-rich soils are orange-brown to yellowish-brown but the organically rich soils are dark brown or black. In other words soil color will also tell us how the soil behaves.
CHEMICAL PROPERTIES OF SOIL
The chemical side of the soil is highly important and is concerned with the proper balancing and availability of soil nutrients in soil. This is calculated primarily by the content of organic matter and the proportion of humus. Nutrient availability is important, but the balance in a right amount is even more important. In other words the soil only produces nutrients if you have the right balance.
Macro-elements
Macro-elements are essential nutrients for plants. These elements are present naturally in the soil in a large amount that can be enhanced by adding fertilizers, manure, and compost. Calcium (Ca), magnesium (Mg), potassium (K), Sulphur (S), phosphate (P), nitrogen (N), and sodium (Na) are important macro-elements.
Micro-elements
Micronutrients or Trace elements are nutrients that are needed in small amounts by plants. Boron (B), copper, cobalt (Co), zinc, silicon (Zn), Iron (Fe) and molybdenum (Mo) are the trace elements. Signs of deficiency occur where the depletion of micro elements in crops is not compensated with fertilizer, manure, and compost additions. However the shortage of trace elements in plants is impossible to overcome because a deficiency or excess of different mineral in the soil is responsible for nutrient deficiencies. Therefore crop analyses helps to recognize and overcome extreme deficiency at the plant level. Therefore soil analyses provide awareness about the minerals that are available in the soil and also tells about the deficiencies that have expected, which can then be solved further by using required nutrition
PH of soil
We can calculate the PH of soil from the free hydrogen ion (H+). Acidic soils having a pH of less than 7 while soils with a pH of above 7 known as basic or alkaline soils. In addition the pH level of the soil suggests that the pH has a major impact on plant nutrients availability, as plants cannot consume macro and microelements in all their forms. The supply of micro and macro elements depends on the pH levels of soil. A soil having a PH below 4.5 restricts the availability of required nutrients. It decreases the activity of soil life and the mineralization of organic matter. however lime is also used to improve the life of soils and promotes decomposition
Salt levels
The amount of salt is the sum of all the salts present in the soil that come from the soil itself or by fertilizer, agricultural compost, and salt marshes or tidal wetlands on the coast. If the soil’s salt level is higher than the plant roots, moisture is drained and the roots die. This inhibits the moisture and accumulation of nutrients by the plant over time and results in poor growth or death. Crops differ in their tolerance to salt and the amounts of salt in which they might still give a good yield. However In saline soils, some crops grow well.
CEC
CEC is the cation exchange abbreviation, which indicates how many cations can be bound to the soil. Mainly Ca2+, Mg2+, K+, Na+ are found in bulk and the cations that are present in lesser amounts are NH4+, Al3+, Fe2+, Mn2+, and H+. A large amount of calcium (Ca2+) is essential for the soil structure. Calcium holds the clay particles to a sufficient distance and thereby creates an airy structure. If the clay particles have plenty of potassium or magnesium, the particles of clay get closer together and it became harder to work on the soil. Therefore the equilibrium between Ca and Mg is thus essential for the appropriate structure of the soil
BIOLOGICAL PROPERTIES OF SOIL
Microorganisms
Micro-organisms are small creatures that are present in the soil as an individual cell and may often form colonies. Therefore, for the inspection of these tiny creatures, a microscope is commonly required.
Macro Fauna
Although the most widely identified nematodes (such as lesion nematode or soya cyst nematode) are pests that feed plant. Roots nematodes are considered the most beneficial organisms. Therefore, Nematodes are essential as they eat a variety of food sources which positions them in the soil food web at multiple trophic levels.
Particulate Organic Matter
The proportion of particulate organic matter (POM) contains all particles of soil organic matter (SOM) smaller than 2 mm and larger than 0.053 mm (Cambardella and Elliot, 1992). POM is biologically and chemically active and forms part of the labile soil organic matter reservoir.
Total Organic Carbon
Total organic carbon (TOC) is carbon that is present in soil organic matter (SOM). Organic carbon (OC) reaches the soil by the decomposition of plant and animal remains, root exudates, and by dead and alive microorganisms that are present in the soil
Soil Enzymes
The reaction rate of soil enzymes increases as the decomposition occurs and releases available plant nutrients. The material used by the soil enzyme is called the substrate.
Soil Respiration
The release of carbon dioxide (CO2) from the soil surface is called soil respiration. The CO2 is the product of a variety of sources, including an aerobic microbial decomposition of the soil organic matter (SOM) to obtain nutrition for their growth and survival (microbial respiration), plant root, and gradually dissolve carbonates in soil solution.
Conclusion
Soil components, characteristics, and its formation properties affect main processes in soil that make it suitable for agricultural practices. Texture, structure, formation, and retention of water, air, and solids in the soil are influential to plant growth and organisms. Therefore understanding and recognizing soil properties and their connections with each other are vital for creating the correct choices relating to soil use and management