Solution (d)

Block Soils 

These Soils are Black in color and also known as Regur Soils. As these soils are best for Cotton Cultivation, it is also known as Black Cotton Soil.  

Hence statement 1 is correct

This type of soil is typical of the Deccan trap (Basalt) region spread over northwest Deccan plateau and is made up of lava flows. They are made up of extremely clayey material. They are well-known for their capacity to hold moisture. 

Hence statement 2 is correct

Also they are rich in soil nutrients, such as calcium carbonate, magnesium, potash and lime. These soils are generally poor in phosphoric contents. 

Hence statement 3 is correct

They develop deep cracks during hot weather, which helps in the proper aeration of the soil. These soils are sticky when wet and difficult to work on unless tilled immediately after the first shower or during the pre-monsoon period. 

Hence statement 4 is correct

Solution (c)

Alluvial Soils

They are mainly formed due to the silt brought by the Rivers; The Ganga, The Brahmaputra and the Indus. In coastal regions, the alluvial soils are formed due to the wave action. 

Hence statement 1 is correct

They are immature and have weak profiles due to their recent origin. Most of the soil is Sandy and clayey soils are not uncommon. These soils are constantly replenished by the recurrent floods.

Hence statement 2 is correct

The proportion of nitrogen is generally low.  And the proportion of Potash, phosphoric acid and alkaline are adequate. 

Hence statement 3 is correct

Solution (c)

Mangroves have a complex salt filtration system and complex root system to cope with salt water immersion and wave action. Mangroves occur worldwide in the tropics and subtropics, mainly between latitudes 25° N and 25° S. They require high solar radiation to filter saline water through their roots. Hence, mangroves are confined to only tropical and sub-tropical coastal waters.

Hence statement 1 is correct.

Ecologically, they provide habitat for a diverse array of terrestrial and marine organisms. The area of mangroves has greater species diversity as it is the junction of terrestrial and marine ecosystems. They have very high salt tolerance and so some species which require this ambience also thrive upon mangroves. 

Hence statement 2 is correct.

Solution (c)

The alluvial soils vary in nature from sandy loam to clay. They are generally rich in potash but poor in phosphorous. 

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 silts. Bhangar represents a system of older alluvium, deposited away from the flood plains. 

Hence statement 2 is correct.

Both the Khadar and Bhangar soils contain calcareous concretions (Kankars). These soils are more loamy and clayey in the lower and middle Ganga plain and the Brahamaputra valley. The sand content decreases from the west to east.

Hence statement 1 is correct.

Solution (c)

Contour farming

The fields are prepared with alternate furrows and ridges to reduce water flow. Ridges at the same level are known as contour. On slopes, however, this type of farming is coupled with terracing. 

Hence statement 1 is correct.

 Crop rotation

It decreases soil loss and preserves the productivity of land. 

Hence statement 2 is correct.

Mulching

It is effective against wind as well as waster erosion. Some such plants as maize stalks, cotton stalks etc.., are used as a ‘mulch’ (a protective layer formed by the stubble). Mulches reduce soil moisture evaporation and increase amount of soil moisture by addition of organic matter to soil. 

Hence statement 3 is correct

Solution (d)

Terai is swampy lowland with silty soils.

Hence Statement 1 is correct

The terai soils are rich in nitrogen and organic matter but are deficient in phosphate.

Hence Statement 2 is correct

These soils are generally covered by tall grasses and forests but are suitable for a number of crops such as wheat, rice, sugarcane, jute.

Hence Statement 3 is correct

Solution (d)

Aluminium production starts with the raw material bauxite, a clay like soil type found in a belt around the equator.

Hence Statement 1 is correct

Three different raw materials are needed to make aluminium, they are – aluminium oxide, electricity and carbon.

Hence Statement 2 is correct

Aluminium is known for its ductile nature and can be recycled over and over again with 100 percent efficiency.

Hence Statement 3 is correct

Solution (a)

Sikkim and Darjeeling Himalayas physical conditions such as moderate slope, thick soil cover with high organic content, well distributed rainfall throughout the year and mild winters makes it very much suitable for tea plantations. 

Solution (a)

• The fine-grained red and yellow soils are normally fertile, whereas coarse-grained soils found in dry upland areas are poor in fertility. They are generally poor in nitrogen, phosphorous and humus.
• Chemically, the black soils are rich in lime, iron, magnesia and alumina. They also contain potash. But they lack in phosphorous, nitrogen and organic matter. The color of the soil ranges from deep black to grey.
• Humus content of the laterite soil is removed fast by bacteria that thrives well in high temperature. These soils are poor in organic matter, nitrogen, phosphate and calcium, while iron oxide and potash are in excess.
• Peaty soils are found in the areas of heavy rainfall and high humidity, where there is a good growth of vegetation. Thus, large quantity of dead organic matter accumulates in these areas, and this gives a rich humus and organic content to the soil.

Solution (c)

• Laterite Soils are formed under conditions of high temperature and heavy rainfall with alternate wet and dry periods.
• Heavy rainfall promotes leaching (nutrients gets washed away by water) of soil whereby lime and silica are leached away and a soil rich in oxides of iron and aluminium compounds is left behind. 
• They lack fertility due to intensive leaching.
• They are found on the summits of Western Ghats and Eastern Ghats.