Question

In addition to the rock particles, the soil contains -
(a) Air and water
(b) Water and plants
(c) Minerals, organic matter, air, and water
(d) Water, air, and plants

Answer 1

Soil, regardless of its source, is composed of components that are both inorganic and organic in nature. Soil is also the burial for many living organisms that themselves contain a wide variety of substances. Soil is also a living ecosystem of aerobic as well as anaerobic bacteria.

Complete step by step answer:
- Soil is an important renewable natural resource that is composed of rock particles, dust, minerals, organic matter, air, and water.
- The soil is a living system and supports plant growth and different types of organisms as well.
- Typically, the soil consists of approximately 45% minerals, 5% organic matter, 20-30% water, and 20-30% air. These are the essential components.
- The various factors responsible for soil formation are relief, parent material, climate, vegetation, human activities, other life-forms, and time.
- The three main minerals present in the soil are NPK - nitrogen, phosphorus, and potassium, respectively. Other major minerals include calcium, magnesium, and sulfur. Trace elements present and required by plants are iron, manganese, zinc, copper, boron, and molybdenum.
- As soil contains a wide variety of aerobic and anaerobic microorganisms due to the presence of air and water, products of their metabolism in the form of organic substances are also present.
So, the correct answer is ‘(c) minerals, organic matter, air, and water’.

Note:
- Soils in India are classified as Alluvial soils, Black soils, Red and Yellow soils, Laterite soils, Arid soils, Saline soils, Peaty soils, and Forest soils.
- The most widespread and productive type of soil is alluvial soil.
- Decomposition of dead organisms by lower organisms is responsible for the formation of humus, increasing the fertility of the soil.