Soils of India Practise Flashcards

A comprehensive set of practice flashcards covering Soil types, formation processes, chemical properties, and irrigation management in India.

What is the definition of soil according to the lecture notes?

Soil is the uppermost part of the crust, a thin surface layer on the earth comprising mineral particles formed by the breakdown of rocks, decayed organic matter, and living organisms.

Identify the inorganic macronutrients and micronutrients found in soil.

Inorganic macronutrients include $\text{N, P, K}$ while inorganic micronutrients include $\text{Fe, Al, Si,}$, Lime, and $\text{Zn}$.

What is the origin and coverage of Alluvial Soil in India?

Alluvial soils are formed by silt deposited by the Indo-Gangetic-Brahmaputra rivers and rocks of the Himalayas; they cover approximately $15~\text{lakh sq km}$ or about $46\%$ of the total area.

What characterizes the chemical properties of Alluvial Soil?

It is generally low in nitrogen (except in the Terai region) but has adequate proportions of Potash, phosphoric acid, and alkalies. The proportion of Iron oxide and lime varies widely.

Why does Red Soil have a reddish color, and when does it turn yellow?

The red color is due to the presence of iron oxide. In regions of high humidity, it turns into hydroxide and the soil becomes yellow.

List the main parent rocks for Red Soil.

The main parent rocks are crystalline and metamorphic rocks like acid granites, gneisses, and quartzites.

What is the parent material and distribution of Black Soil in India?

The parent material is volcanic rocks from the Deccan and Rajmahal traps. It covers $46~\text{lakh sq km}$ ($13\%$ of the total area) across Maharashtra, Madhya Pradesh, and other states.

Why is Black Soil referred to as 'self-ploughing' soil?

In summer, the moisture evaporates and the soil shrinks, creating broad and deep cracks that permit oxygenation to sufficient depths.

Under what climatic conditions does Laterite Soil form?

It forms under conditions of high temperature and heavy rainfall with alternate wet and dry periods, facilitating the process of leaching.

Explain the process of leaching in Laterite Soil formation.

Heavy rainfall washes away lime and silica (leaching), leaving behind soil rich in oxides of iron and aluminium compounds.

What are the primary characteristics of Peaty or Marshy Soil?

They are rich in accumulated organic material (humus), dark in color, acidic, highly moisture retentive, and often waterlogged/saline, making them infertile despite high humus content.

What is Loessic Soil and where is it specifically mentioned in India?

It is formed from wind-deposited fine particles (Loess) and is found west of the Aravalli hills around the Indira Gandhi Canal.

Define the soil-forming process of Gleisation.

Gleisation occurs during waterlogging conditions and the absence of oxygen, leading to the formation of swampy or gley soil with blue-green color patches, common in mangrove areas.

Contrast Laterization and Podsolization.

Laterization occurs in warm tropical regions where silica and calcium leach downward while iron and aluminum remain; Podsolization occurs in cold temperate regions where iron and aluminum leach downward, leaving the upper layer rich in silica.

How does the application of gypsum help treat soil salinity?

Gypsum ($\text{calcium sulfate, CaSO}_4$) reacts with sodium to form calcium sulfate, which is more soluble than sodium sulfate, allowing sodium to be leached out and improving drainage.

What is the difference between Irrigation Potential Created (IPC) and Irrigation Potential Utilised (IPU)?

IPC is the total irrigation capacity developed through projects, while IPU is the actual area being irrigated using that available infrastructure.

What role did the Mihir Shah Committee suggest for the management of IPU?

It recommended that IPU should be the responsibility of communities (SHGs, Farmer organizations, Cooperatives) in addition to the state government.

Describe the A-horizon and E-horizon in a soil profile.

The A-horizon is dark, fertile, and consists of minerals mixed with organic material; the E-horizon (Eluviation) is a light-colored layer below A characterized by the loss of clay, iron, and aluminum due to leaching.

Describe the functions of the C-horizon and R-horizon.

The C-horizon consists of partially weathered rock fragments and acts as the transition to bedrock; the R-horizon is the lowest layer made of solid, unweathered parent rock.

What is Capillary Action in the context of soil?

It is the upward movement of water along with dissolved salts, common in dry regions with high evaporation, often leading to salinisation.