Soil is a natural resource comprising of mineral particles, organic matter, various microorganisms, water and air that forms the upper layer of the Earth's crust. Soil serves as a critical medium for plant growth which is necessary for sustenance of terrestrial life. It also provides shelter for many types of living beings such as earthworms, centipedes, rats, microorganisms etc.
Soil formation is a continuous process and during this process it gets arranged in layers. Each layer is called the soil horizon.
Soil profile is the vertical section of soil containing different horizons. A mature soil profile comprises six different layers or horizons. Each horizon is represented by alphabet O, A, E, C, B, and R. Immature soils may lack some of these layers.
The process of soil formation, which involves the weathering of rocks and minerals, the addition of organic matter, and the actions of organisms and environmental factors is known as Pedogenesis.
Entisols: Soils with minimal horizon development, often found in areas of recent deposition or erosion.
Inceptisols: Soils with limited horizon development, showing some signs of soil formation but lacking well-defined horizons.
Aridisols: Soils found in arid and semi-arid regions, characterized by low organic matter content and distinct horizons due to salt accumulation or other processes.
Mollisols: Soils with a thick, dark surface horizon rich in organic matter, commonly found in grassland ecosystems.
Alfisols: Soils with a well-developed horizon sequence, typically found in temperate forests and characterized by moderate leaching and accumulation of clay and minerals.
Ultisols: Highly weathered soils found in humid tropical and subtropical regions, often with a clay-rich B horizon and low fertility.
Oxisols: Highly weathered soils found in tropical regions, characterized by a deeply weathered profile, low nutrient content, and high levels of iron and aluminum oxides.
Vertisols: Clay-rich soils with a high content of swelling clays, prone to cracking when dry and swelling when wet, commonly found in seasonally wet climates.
Histosols: Organic soils formed from the accumulation of plant material in wetland environments, characterized by high organic matter content and low bulk density.
Andisols: Soils formed from volcanic ash and other volcanic materials, typically found in volcanic regions and characterized by high fertility and unique mineralogy.
Gelisols: Soils with permafrost within two meters of the soil surface, commonly found in cold regions and characterized by cryoturbation and other periglacial processes.
Spodosols: Acidic soils found in forested regions with cool, moist climates, characterized by a bleached horizon (E horizon) and accumulation of organic matter and aluminum.
| Type of Soil | How formed |
|---|---|
| Alluvial Soil | By silt deposition brought by rivers. |
| Black Soil | By weathering of lava deposits on the Deccan Plateau. |
| Red and Yellow Soil | By weathering old crystalline or metamorphic rocks. |
| Laterite Soil | Due to leaching by heavy rains and destruction of humus by bacteria. |
| Arid Soil | By weathering of rocks in dry conditions. |
| Saline Soil | By salt deposition by tides, rivers or sea breeze. |
| Peaty Soil | Due to accumulation of larges amounts of organic matter in the soil. |
| Fact to remember | Type of Soil |
|---|---|
| The soil most common in Indo-gangetic plains | Alluvial Soil |
| The soil which swells when wet and develops cracks when dry | Black Soil |
| The soil which owes its colour to oxides of iron | Laterite Soil |
| The soil which requires least use of fertilisers | Alluvial Soil |
| The soil which requires least tilling because of its characteristic of self-ploughing | Black Soil |
| The kind of soil which is treated with gypsum to make it suitable for cropping | Alkaline soil |
| The soil which is poor in soluble salts | Laterite |
| The soil which is rich in surface accumulation of organic matter | Peaty soil |
| The soil which is most suitable for cultivation of cotton | Black Soil |
| Khadar and Bhangar are types of | Alluvial Soil |
| The soil which also known as Regur Soil | Black Soil |
| The soil which is generally unfit for cultivation | Laterite Soil |
| The soil which is commonly used for making bricks | Laterite Soil |
A crop is a cultivated plant or agricultural produce that is grown and harvested for food, feed, fiber, medicinal plants, and other uses. Crops are intentionally cultivated by humans for various purposes, and they form the basis of agriculture, providing sustenance and raw materials for numerous industries.
Crops may be classified by the use they are put by people growing them. Broadly, they may be classified as under:
| Point to remember | Crop |
|---|---|
| The crop which requires water-logging for its cultivation | Rice |
| The crop best suited in areas where rain falls only for two months | Pulses |
| The ideal crop for areas with rainfall above 200 cm and sloping hills | Tea |
| The crop which requires a large amount of rainfall and no standing water | Tea |
| The plants which are best for biological nitrogen fixation of the soil | Legumes |
| The crops grown for sale in the market (as against consumption by the farmer) are known as | Cash crops |
| Cropping Season | Period | Major Crops |
|---|---|---|
| Kharif | June to October | Rice, millets |
| Rabi | November to March | Wheat, barley, mustard |
| Zaid | March to June | Water melon, cucumber, musk melon, sugarcane |
| Kharif means autumn in Arabic and kharif crops are harvested in winter, Rabi means spring in Arabic and rabi crops are harvested in spring (March) | ||