Soil Science and Fertilizers

Plants primarily require water and air (carbon dioxide and oxygen) to carry out photosynthesis and cellular respiration. While soil is important for nutrients, air and water are the fundamental building blocks for growth.

Nutrient recycling refers to the process by which nutrients are moved, exchanged, and reused within an ecosystem, such as the decomposition of organic matter back into the soil.

Plants are highly sensitive to their environment. Factors such as soil quality, nutrient availability, water, and temperature directly impact their growth and health.

Topsoil, which corresponds to the upper layers of the soil profile, contains the highest concentration of organic matter and microorganisms. This organic material, known as humus, is formed from decomposed leaves, plants, and organisms, providing essential nutrients for plant growth. Sub-soil and sandy layers contain significantly less organic material.

The organic fertilizers are used to improve the fertility of alluvial soil. This type of fertilizer originates from an organic source. Some examples include fish extracts, manure, and compost. 

 The burning of fossil fuels like coal natural gas, petroleum in automobiles, industries and thermal plants leads to increase in air pollution.

Bacteria and fungi carry out the decomposition of plant residues, breaking them down and holding the nutrients in their bodies, this prevents the nutrients leaching out into the soil. They hold the nutrients until the nutrients are consumed- by protozoa, nematodes and then release the remaining nutrients in plant available form.

Lime (calcium carbonate or calcium hydroxide) is an alkaline substance used to raise the pH of acidic soils, neutralizing the acidity. Gypsum, on the other hand, is typically used to treat alkaline or sodic soils.

Soil pH, nutrient levels, and day length are physical and chemical components of an environment that do not derive from living organisms, classifying them as abiotic factors.

Fertile soil is rich in nutrients and highly capable of supporting abundant plant growth. Early agricultural civilizations settled near river valleys because the flooding left behind fertile soil ideal for farming.

Decomposers, such as fungi and bacteria, are responsible for breaking down dead organic material and returning essential nutrients to the soil.

In a mycorrhizal association, the fungus provides the plant with minerals and water, while the plant provides the fungus with carbohydrates and other organic compounds.

Soil provides the necessary nutrients, water retention, and physical support required for plants to grow. Water alone is used in hydroponics, but soil is the standard medium for general plant growth.

Unlike the carbon, nitrogen, and water cycles, the phosphorus cycle does not include a significant gaseous phase. Phosphorus primarily cycles through soil, water, and living organisms.

Decomposers are organisms that break down dead organic matter, thereby recycling nutrients back into the ecosystem. Bacteria and fungi are classic examples of this role.