Soil Types of India — Set 11

Correct Answer: C. Black soil

Black soil has the highest moisture-retaining capacity among Indian soil types due to its high clay content, particularly montmorillonite clay. It can retain moisture for a long time, which is why it supports cotton cultivation even without irrigation in many dryland areas. The swelling of clay when wet and the formation of cracks when dry are manifestations of this extreme moisture behaviour. This moisture retention makes Black soil ideal for cotton, which needs sustained moisture during its growing season.

Correct Answer: C. Lime (calcium carbonate)

Acid soils can be improved by applying agricultural lime (calcium carbonate, CaCO3) or quicklime or slaked lime. Lime neutralizes the acidity by reacting with hydrogen ions in the soil and raising the pH. Liming also supplies calcium to the soil, which improves soil structure. Regular liming of Laterite and acidic Forest soils in India is essential for growing food crops on them.

Correct Answer: B. It has been intensely leached and is rich in iron and aluminium oxides but poor in nutrients

The main distinguishing characteristic of Laterite soil is that it has been intensely leached by heavy rainfall, removing silica and soluble nutrients, and leaving behind a soil rich in iron and aluminium oxides. This leaching makes Laterite soil poor in nitrogen, phosphorus, potassium, and organic matter. The iron and aluminium oxides give the soil its brick-red colour and hard, compact nature when dry. Laterite literally means 'brick' in Latin, referring to the soil's tendency to harden like brick on exposure to air.

Correct Answer: B. National Bureau of Soil Survey and Land Use Planning

NBSS&LUP stands for the National Bureau of Soil Survey and Land Use Planning. It is an apex institute under the Indian Council of Agricultural Research (ICAR) located at Nagpur, Maharashtra. NBSS&LUP is responsible for systematic soil resource surveys, mapping, and the preparation of land use plans for India. It has published detailed soil maps of India at various scales and provides soil resource information for agricultural and developmental planning.

Correct Answer: B. Texture refers to particle size proportions; structure refers to how particles are arranged into aggregates

Soil texture refers to the relative proportions of sand, silt, and clay particles in the soil (a fixed property that cannot be easily changed). Soil structure refers to the way these particles clump together into aggregates or 'peds'. Good soil structure (granular) improves drainage, aeration, and root penetration. Soil structure can be improved by adding organic matter, while texture is essentially a fixed characteristic of the soil.

Correct Answer: B. Ganga-Brahmaputra delta (Sundarbans)

The Ganga-Brahmaputra delta, particularly the Sundarbans region, contains the most extensive peaty and marshy soils in India. The tidal swamps and mangrove forests of the Sundarbans create conditions of perpetual waterlogging, which leads to peat formation. The saline tidal water also contributes to the saline character of the soil. This vast delta is shared between India (West Bengal) and Bangladesh and is a UNESCO World Heritage Site.

Correct Answer: C. Cotton

Black soil of the Deccan Plateau is most famous for cotton cultivation, which is why it is also called 'Black Cotton Soil'. Maharashtra, the state with the most extensive Black soil, is India's largest cotton producer. The soil's high moisture retention, neutral to alkaline pH, and calcium-rich composition create ideal conditions for cotton fibre quality. Cotton grown on Black soil in Maharashtra, Vidarbha, and Marathwada regions is of the premium short-staple type.

Correct Answer: C. Laterite soil

Laterite soil is formed primarily in hot, humid tropical climates with high annual rainfall alternating with a dry season. The intense rainfall causes heavy leaching, which removes soluble minerals including silica, while iron and aluminium oxides, being insoluble, remain and accumulate. India's Western Ghats, eastern coast, and northeastern hills, which receive heavy monsoon rainfall, are the main Laterite soil regions. The alternating wet and dry seasons also cause the soil to harden into brick-like formations.

Correct Answer: C. Earthworms aerate and mix the soil, improve drainage, and add organic matter through their castings

Earthworms are highly beneficial to soil health as they burrow through the soil, improving aeration and drainage. Their burrowing also mixes organic matter into deeper soil layers and creates channels for root growth. Earthworm castings (excreta) are rich in nitrogen, phosphorus, and potassium and are a valuable organic fertilizer. Charles Darwin recognised earthworms as the 'intestines of the earth', and their presence is an indicator of healthy, productive soil.

Correct Answer: B. Uttar Pradesh

Uttar Pradesh has the maximum area under alluvial soil among Indian states, as the entire state lies within the Ganga-Yamuna alluvial plains. The deep, fertile alluvial soil of Uttar Pradesh supports intensive cultivation of wheat, rice, sugarcane, potatoes, and pulses. The state is one of India's most important agricultural states due to this extensive alluvial soil cover. The alluvial deposits in parts of UP are several thousand feet deep.