Ans: B

Exp:

Statements 1 and 2 are correct: Chemically, Black soil is rich in lime, iron, magnesium and aluminium, but it lacks phosphorus, nitrogen and organic material. The colour of the soil ranges from deep black to grey.

Statement 3 is incorrect: Black cotton covers most of the Deccan plateau, which includes parts of Maharashtra, Madhya Pradesh, Gujarat, Andhra Pradesh and some parts of Tamil Nadu. These soils are generally clayey, deep and impermeable. They swell and become sticky when wet and shrink when dried. So during the dry season, these soils develop wide cracks. Thus, there occurs a kind of ‘self ploughing’. Due to this reason, the black soil retains moisture for a very long period of time, which helps crops, especially the rain-fed ones, to sustain themselves even during the dry season.

Ans: D

Exp:

Statement 1 is incorrect: Weathering describes the in situ, not ex situ process by which soil, rocks and minerals are changed by physical and chemical processes into other soil components. Weathering is an integral part of soil development. Depending upon the soil-forming factors in an area, weathering may proceed rapidly over a decade or slowly over millions of years. 

Statement 2 is incorrect: Iluviation refers to the deposition of dissolved constituents or suspended particles into lower layers through the movement of water. Illuviation has a significant effect on the evolution of the soil. Zones in the soil where illuviation occurs, or has occurred, are often called illuvial zones or “B horizons”. B horizons often go through significant change through the deposition of clay minerals, iron, humus, and calcium carbonate. 

Statement 3 is incorrect: Eluviation is the process by which soil constituents are washed out from the upper layers to the lower layers through percolating water. The rate of eluviation is influenced by rainfall, high temperatures, and removal of protective vegetation. “A horizon” is considered as a layer of eluviation. In extreme cases, eluviation may result in the removal of most insoluble materials, such as quartz, hydroxides of iron and aluminium, and iron oxides. Such soils are referred to as laterite soil.

Ans: A

Exp:

The laterite soils develop in areas with high temperatures and high rainfall. These are the results of intense leaching due to tropical rains. With rain, lime and silica are leached away, and soils rich in iron oxide and aluminium compounds are left behind. The humus content of the soil is removed quickly by bacteria that thrives well at high temperatures. These soils are poor in organic matter, nitrogen, phosphate, and calcium, while iron oxide and potash are in excess. Hence, laterites are not suitable for cultivation; however, the application of manures and fertilisers is required to make the soils fertile for  cultivation. Red laterite soils in Tamil Nadu, Andhra Pradesh and Kerala are more suitable for tree crops like cashewnuts. Laterite soils are widely cut into bricks for use in construction. These soils have mainly developed in the higher areas of the  Peninsular plateau. Laterite soils are commonly found in Karnataka, Kerala, Tamil  Nadu, Madhya Pradesh, and the hilly areas of Odisha and Assam.

Ans: C  

Exp:

Soil degradation is the physical, chemical, and biological degradation of soil quality. It can be the loss of organic matter, decline in soil fertility, etc.

Option 1 is correct : Prevention of over-irrigation, use of efficient irrigation methods, such as drip irrigation and micro irrigation, etc., prevent unwanted soil degradation outcomes like secondary salinization and solidification of fields.

Option 2 is correct : The practise of crop rotation by alternating the types of crops grown in particular fields each season, helps to break pest and disease cycles, enhance soil fertility, and reduce the risk of nutrient depletion.

Option 3 is correct: Rationalisation of fertiliser subsidies  will lead to the application of  the right amount of fertiliser. VRA (variable rate application) based on soil diagnostics and satellite imagery analytics can help determine how much fertiliser is needed in each zone to achieve the desired yield without causing harm to the land and the surrounding environment.

Option 4 is correct: Practise of terrace farming on the slopes: Agricultural terraces can be used to reduce the slope of the land, minimising the erosive power of surface water flow. Furthermore, terrace farming enhances pedogenetic processes.

Option 5 is incorrect: Soil Compaction: Repeated runs of heavy agricultural machines over the same areas enhance soil compaction. Plant roots can’t sprout through such a thick mass. Thus, compaction has a devastating effect on agricultural crop growth and development and leads to soil degradation too.

Ans: D

Exp:

Option 1 is incorrect : Alluvial soils are depositional soils, transported and deposited by rivers and streams. Through a narrow corridor in Rajasthan, they extend into the plains of Gujarat. In the Peninsular region, they are found in deltas of the east coast and in the river valleys. The alluvial soils vary in nature from sandy loam to clay. They are generally rich in potash but poor in phosphorus. 

Option 2 and 3 are incorrect : In the Upper and Middle Ganga plain, two different types of alluvial soils have developed, viz. Khadar and Bhangar. Khadar is the new alluvium and is deposited by floods annually, which enriches the soil by depositing fine silt. Bhangar represents a system of older alluvium, deposited away from the flood plains. Both the Khadar and Bhangar soils contain calcareous concretions (Kankars). These soils are more loamy and clayey in the lower and middle Ganga plains and the Brahmaputra valley. The sand content decreases from west to east. The colour of the alluvial soils varies from light grey to ash grey. Its shades depend on the depth of the deposition, the texture of the materials, and the time taken for attaining maturity. Alluvial soils are intensively cultivated.

Option 4 is correct : Alluvial soils are highly fertile. They are widespread in the northern plains and river valleys. These areas house large population in Northern India. Thus, Alluvial soils are intensively cultivated. These soils cover about 40 percent of the total area of the country. This soil supports the growth of a wide variety of crops such as rice, wheat, sugarcane, cotton, jute, potatoes, and vegetables.