Soil Types of India — Set 15

Correct Answer: B. Cover cropping

Cover cropping involves growing crops specifically to cover and protect the soil surface between main crop seasons. Cover crops like cowpea, sunhemp, and mustard protect the soil from splash and sheet erosion, improve organic matter content, and suppress weeds. Some cover crops like legumes also fix nitrogen, improving soil fertility for the next main crop. Cover cropping is an important component of sustainable soil management in India.

Correct Answer: B. Soil temperature decreases with increasing altitude at the rate of about 6°C per 1000 metres

Soil temperature decreases with increasing altitude at the rate of approximately 6°C per 1000 metres (the environmental lapse rate). This is why mountain soils are cooler and have slower organic matter decomposition compared to lowland soils, leading to accumulation of humus. The lower soil temperatures in the Himalayas and northeastern hills limit microbial activity and slow down nutrient cycling. This is why forest and mountain soils tend to have high organic carbon but may not be very productive for conventional crops.

Correct Answer: C. Tamil Nadu

Tamil Nadu has the largest area under Red soil in India, covering most of the non-delta areas of the state. Red soil extends across much of the peninsular region but is particularly dominant in Tamil Nadu. The soil is formed from the weathering of ancient igneous and metamorphic rocks (Charnockite, gneiss, granite) that underlie most of Tamil Nadu. Despite being less fertile, Red soil supports cultivation of millets, groundnut, pulses, and cotton with proper management.

Correct Answer: B. It creates barriers along contour lines that slow runoff and trap eroded soil

Contour bunding involves constructing earthen embankments (bunds) along contour lines of equal elevation on sloping land. These bunds act as barriers that slow down and break the flow of runoff water, reducing its erosive power and trapping eroded soil. They also help in rainwater harvesting by impounding water and allowing it to percolate into the soil. Contour bunding is widely practiced in the rainfed agricultural areas of peninsular India to conserve both soil and water.

Correct Answer: B. Iron oxide (Fe2O3) and Aluminium oxide (Al2O3)

The high concentrations of iron oxide (Fe2O3) and aluminium oxide (Al2O3) in Laterite soil cause it to harden irreversibly on exposure to air and drying. This hardened laterite can be cut into blocks and used as building material, which is widely practiced in Kerala and coastal Karnataka. The name 'laterite' literally means 'brick' (from Latin 'later'), reflecting this property. Ancient temples and buildings in southern India were constructed using laterite blocks.

Correct Answer: B. Well-drained oxidised soils tend to be red/brown; poorly drained reduced soils tend to be grey/blue-grey

Soil colour is a good indicator of drainage conditions. Well-drained soils that have good oxygen supply show red, brown, or yellowish colours due to oxidised (ferric) iron compounds. Poorly drained waterlogged soils have reduced oxygen, causing iron to be in its reduced (ferrous) form, giving the soil grey, blue-grey, or greenish (gleyed) colours. This colour indicator is used by soil scientists to assess historical drainage patterns. Red soils and Black soils of India are well-drained, while peaty soils show gleyed grey colours.

Correct Answer: B. The original rock or sediment material from which soil has formed

Parent material refers to the original rock or unconsolidated mineral material from which a soil develops through the process of weathering and soil formation (pedogenesis). Different parent materials produce different soil types: basalt produces Black soil, granite and gneiss produce Red soil, and river sediments produce Alluvial soil. The chemical composition of the parent material largely determines the mineral nutrient content of the resulting soil. Understanding parent material is fundamental to interpreting soil distribution in India.

Correct Answer: C. Soil erosion

Soil erosion is the process by which soil particles are detached from the soil surface and transported to another location by erosive agents such as water, wind, or glaciers. Water erosion includes splash, sheet, rill, and gully erosion, while wind erosion (aeolian erosion) is dominant in arid regions. Glacial erosion is significant in high-altitude Himalayan areas. Soil erosion is one of the most serious forms of land degradation in India, affecting millions of hectares of agricultural land.

Correct Answer: C. Wind erosion (aeolian erosion)

Wind erosion (aeolian erosion) causes maximum damage in the Rajasthan desert (Thar Desert) region. The strong, hot, dry winds of Rajasthan pick up sand and dust particles, form sand dunes, and transport them across large distances. This process is called deflation (removal of fine particles) and abrasion (sandblasting of rock surfaces). Wind erosion covers fertile land with sand, buries villages and agricultural land, and contributes to desertification in western Rajasthan.

Correct Answer: B. Indian Council of Agricultural Research

ICAR stands for the Indian Council of Agricultural Research, which is the apex body for coordinating, guiding, and managing agricultural research and education in India. ICAR is headquartered in New Delhi and operates a network of national institutes including NBSS&LUP at Nagpur for soil research. ICAR is responsible for developing improved crop varieties, soil management technologies, and agro-climatic zone-based recommendations. It plays a crucial role in improving India's agricultural productivity and soil health.