Soil Science

Loamy soil has a good balance of sand, silt, and clay, providing excellent aeration and water retention, which is ideal for pulses and lentils.

Soil quality is influenced by various environmental factors including wind, rainfall, light, temperature, and humidity, which affect soil formation and nutrient content.

Clayey soil has high water retention capacity, which is essential for paddy crops that require standing water for growth.

Explanation: Silt is granular material of a size somewhere between sand and clay, whose mineral origin is quartz and feldspar. Silt may occur as a soil or as sediment mixed in suspension with water (also known as a suspended load) in a body of water such as a river. Silty soil is usually more fertile than other types of soil, meaning it is good for agriculture.

Clayey soil is rich in nutrients like nitrogen and phosphorus, which are essential for the growth of wheat.

Gram (chickpea) grows best in loamy soil, which provides good drainage and aeration, preventing waterlogging.

Clay soil has the smallest particle size, leading to very small pore spaces and low porosity compared to sandy or loamy soils.

Eolian soil refers to soil or sediment transported and deposited by the wind. Alluvial is water-borne, and Glacial is ice-borne.

Soil is a complex mixture consisting of mineral particles (sand, silt, and clay), organic matter (humus), water, and air. These components together define the soil structure and fertility.

Colluvium is a type of parent material that moved down slope due to gravitational forces (in some cases water may play a role in initiation of the movement). Colluvium is heterogeneous, unsorted material of all particle sizes (from boulders to clay) with relatively little abrasion to round the particles. Consequently, colluvium consists of very sharp, angular rock fragments accumulated at the base of steep slopes.
Aeolian soil : A type of soil that is transported from one place to another by the wind.
Alluvium  is loose, unconsolidated (not cemented together into a solid rock) soil or sediments, which has been eroded, reshaped by water in some form, and redeposited in a non-marine setting.
Glacial soil  Unsorted, non-stratified glacial deposits consisting of clay, silt, sand, and boulders transported and deposited by glacial ice.

Colluvium is a type of parent material that moved down slope due to gravitational forces. Colluvium is heterogeneous, unsorted material of all particle sizes (from boulders to clay) with relatively little abrasion to round the particles.

Black soil is used to make matkis and surrahis. This is because it provides proper support due to air spaces between their particles. It can also retain water for a long period of time. Along with this, it can withstand a large amount of climatic change also.

Laterite is a soil layer, that is rich in iron oxide and derived from a wide variety of rocks weathering under strongly oxidizing and leaching conditions. It forms in tropical and subtropical regions, where the climate is humid. When the velocity of running water decreases the heaviest particles are deposited on a riverbed. The finest particles (gravel, silt, sand, and clay) are deposited at the mouth of the river, forming a delta made of alluvial soil. 

Alluvial soils are most extensive soil. It is formed due to deposition of the rivers brought down from the upper course of the river. It is found on the combined plain land of the Indus and the Ganga-Brahmaputra rivers which includes Punjab, Haryana, U.P., Bihar and West Bengal. The deltaic alluvium is found in deltas of the Ganga-Brahmaputra, Godavari, Mahanadhi and Kaveri rivers. The coastal alluvium is found in coastal sides of Peninsular India - called riverine soils it is originally found in river basins.

Dead plants and animals are degraded in soil by decomposing bacteria and fungi. The material formed after this decomposition activity is called humus. Humus is very rich in nutrients and black in color. Hence topsoil is the darkest. Greater the amount of humus more is the soil productivity. Thus the correct answer is option A.