All questions of Soils for UPSC CSE Exam

• Alkali, or alkaline, soils are clay soils with high pH (> 8.5), a poor soil structure and a low infiltration capacity. Often they have a hard calcareous layer at 0.5 to 1-metre depth.
• Alkali soils owe their unfavourable physicochemical properties mainly to the dominating presence of sodium carbonate which causes the soil to swell and difficult to clarify/settle.

Black soil rich in iron oxide, alumina but very low in humus, phosphates and nitrogen. Also named as regur and best soil for cotton cultivation.

• Laterite soil is characterized by the possession of iron oxides with red colour. Nitrogen, Phosphorus and potash are not present in proper quantities so it shows low fertile texture.
• Tapioca and cashew nuts are generally grown in such soil. This soil is found loss or more in states- Odisha, Maharashtra, Andhra, Tamil Nadu, Karnataka, Meghalaya and West Bengal.

Answer :

• b)
  capillary water

 Capillary water

Red Soils of India

• Red soils are one of the most important types of soils found in India. They cover about 10.6% of the total land area of the country.

• The colour of the soil is red due to the presence of ferric oxide content.

• Red soils are generally acidic in nature and have a pH range of 5-6.5.

• They are found in areas with low rainfall and high temperature, such as the Deccan Plateau, parts of Tamil Nadu, Karnataka, Andhra Pradesh, and Maharashtra.

Characteristics of Red Soils

1. Colour: The colour of the soil is red due to the presence of ferric oxide content.

2. Texture: Red soils are generally sandy in texture, but they can also be loamy and clayey.

3. Porosity: Red soils are porous and have a friable structure. This means that they are easy to cultivate and have good drainage.

4. Nutrient content: Red soils are deficient in nitrogen, phosphorus, and organic matter. However, they are rich in iron, aluminium, and magnesium.

5. Water-holding capacity: Red soils have low water-holding capacity, which makes them unsuitable for crops that require a lot of water.

6. Fertility: Red soils are generally poor in fertility, but they can be made fertile by adding organic matter and fertilizers.

Conclusion

The correct option is (b) 1 and 3. Red soils of India are characterized by their red colour due to high ferric oxide content, porous and friable structure, and low water-holding capacity. They are deficient in nitrogen, phosphorus, and organic matter but rich in iron, aluminium, and magnesium. Red soils are generally found in areas with low rainfall and high temperature.

Black soil is called regur also

Laterite soil - Punjab because laterite soil found in hilly area where high humidity and temp conditions which are favourable for tea cultivation

The alluvial soil is spread all over the plains of north India.

Black Soil of India

Statement 1: Black soil becomes sticky when it is wet.
Yes, this statement is correct. Black soil, also known as regur soil or black cotton soil, is a type of soil that is found in India. It is known for its high fertility and moisture-retaining capacity. When the soil gets wet, it becomes sticky and compact due to its high clay content. This stickiness can make it difficult for water to drain properly, leading to waterlogging in some areas.

Statement 2: Black soil contains adequate nitrogen as well as phosphorus required for the growth of plants.
This statement is incorrect. While black soil is rich in certain nutrients like calcium, magnesium, and potassium, it generally lacks in nitrogen and phosphorus. Nitrogen and phosphorus are crucial elements for plant growth and development. However, black soil is deficient in these nutrients, which means that additional fertilizers need to be added to enhance the soil's fertility and provide the necessary nitrogen and phosphorus for plants.

Conclusion:
In conclusion, statement 1 is correct as black soil does become sticky when wet. However, statement 2 is incorrect as black soil generally lacks adequate nitrogen and phosphorus for plant growth. Therefore, the correct answer is option 'A' - Only 1.

• Red soils develop in a warm, temperate, wet climate under deciduous forests and have thin organic and mineral layers overlying a yellowish-brown leached layer resting on a red layer made of iron oxide(ferric oxide).
• Red soils generally form from iron-rich sediments. They are usually poor growing soils, low in nutrients and humus and difficult to cultivate.

Mulches are materials placed over the soil surface to maintain moisture and improve soil conditions. Mulching has proven to be an effective soil conservation practice, reducing both wind and water erosion during the winter period.

About Laterite Soils in India

Laterite soils are common in India, especially in the tropical regions with seasonal rainfall. These soils are formed by the leaching of soluble minerals like silica, calcium, and magnesium due to heavy rainfall. The remaining soil is rich in iron and aluminum oxides, which give it a reddish-brown color.

Buchanan first studied these soils in India, and they are well developed on the summits of the Sahyadris and the Eastern Ghats. However, there is one statement that is not correct about laterite soils in India, which is:

- These soils are poor in iron but rich in nitrogen.

This statement is incorrect because laterite soils are actually poor in nitrogen but rich in iron and aluminum oxides. The leaching of soluble minerals by heavy rainfall removes most of the nitrogen from the soil, making it unsuitable for agriculture without fertilization.

Conclusion

In conclusion, laterite soils are an important soil type in India, especially in the tropical regions with seasonal rainfall. They are formed by leaching of soluble minerals due to heavy rainfall, and they are rich in iron and aluminum oxides but poor in nitrogen. Buchanan first studied these soils, and they are well developed on the summits of the Sahyadris and the Eastern Ghats.