World Soil Day (WSD) is celebrated annually on December 5 to raise awareness for healthy soils worldwide, which lay at the foundations of agricultural development, healthy food production, and are key to basic survival as well as our planet’s sustainable future. 

Background

• An international day to celebrate Soil was recommended by the International Union of Soil Sciences (IUSS) in 2002. Under the leadership of the Kingdom of Thailand and within the framework of the Global Soil Partnership, the Food and Agriculture Organisation (FAO) has supported the formal establishment of World Soil Day as a global awareness raising platform. 

• The FAO Conference unanimously endorsed World Soil Day in June 2013 and requested its official adoption at the 68th UN General Assembly. In December 2013 the UN General Assembly responded by designating  December 5, 2014 as the first official World Soil Day and gave the FAO Global Soil Partnership (GSP) the mandate to coordinate the implementation of its global communication campaign.

• The date of December 5 was chosen because it corresponds with the official birthday of the late King Bhumibol Adulyadej, King of Thailand, who was one of the main proponents of this initiative.

• Since then, World Soil Day has adopted a different theme each year in order to highlight areas needed for action — threats to soil resources — and provide a common focus to the campaign.

• World Soil Day campaigns call on governments, education and academic sectors, farmers, scientists, youth, business, and civil society to take action, trigger international attention and build new working relationships with other strategic partners and donors.

• Over the years, World Soil Day has gained great momentum and has become one of the most celebrated days of the UN calendar reaching hundreds of millions. 

The theme of World Soil Day 2020

• This year, by addressing the increasing challenges of soil management, the FAO campaign ‘Keep soil alive, protect soil biodiversity’ aims to raise awareness of the importance of sustaining healthy ecosystems and human well-being. By encouraging people around the world to engage in proactively improving soil health, the campaign also aims to fight soil biodiversity loss.

Significance of the theme

• Plants nurture a whole world of creatures in the soil, that in return feed and protect the plants. This diverse community of living organisms keeps the soil healthy and fertile. This vast world constitutes soil biodiversity and determines the main biogeochemical processes that make life possible on Earth.

• This year’s theme urges us to focus our attention on the workers belowground — from tiny bacteria to agile millipedes and slimy earthworms — all of which contribute to processes that are indispensable to life on Earth.

• Soil organisms are responsible for many critical ecosystem processes, on which humans depend: from supporting plant growth, to storing carbon and being a vast reservoir for pharmaceuticals.

• Soil is a living resource, home to more than one quarter (25 per cent) of our planet’s biodiversity.

• Soil biodiversity is an essential component of soil health. Healthy soils produce more nutritious and safer food. Nearly 95 per cent of our food comes from soils.

• Soil organisms help soils store carbon and reduce GHG emissions. Soil biodiversity contributes to the remediation of soil pollution by breaking down contaminants.

The soils of India

On the basis of genesis, colour, composition and location, the soils of India have been classified into:

1) Alluvial soil

2) Black soil

3) Red and Yellow soil

4) Laterite soil

5) Arid soil

6) Saline soil

7) Peaty soil

8) Forest soil.

Alluvial soil

Alluvial soil is widespread in the northern plains and the river valleys. These cover about 40 per cent of the total area of the country. They 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. They are generally rich in potash, but poor in phosphorus. The colour of the alluvial soils varies from the light grey to ash grey. 

Black soil

Black soil covers most of the Deccan Plateau which includes parts of Maharashtra, Madhya Pradesh, Gujarat, Andhra Pradesh and some parts of Tamil Nadu. The black soil is generally clayey, deep and impermeable. They swell and become sticky when wet and shrink when dried. So, during the dry season, these soil develop wide cracks. Thus, there occurs a kind of ‘self ploughing’. Because of this character of slow absorption and loss of moisture, the black soil retains the moisture for a very long time, which helps the crops, especially, the rain fed ones, to sustain even during the dry season. Chemically, the black soils are rich in lime, iron, magnesia and alumina. They also contain potash. But they lack in phosphorus, nitrogen and organic matter. The colour of the soil ranges from deep black to grey.

Red and Yellow soil

Red soil develops on crystalline igneous rocks in areas of low rainfall in the eastern and southern part of the Deccan Plateau. Along the piedmont zone of the Western Ghat, a long stretch of area is occupied by red loamy soil. Yellow and red soil are also found in parts of Odisha and Chattisgarh and in the southern parts of the middle Ganga plain. The soil develops a reddish colour due to a wide diffusion of iron in crystalline and metamorphic rocks. It looks yellow when it occurs in a hydrated form. 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, phosphorus and humus.

Laterite soil

Laterite has been derived from the Latin word ‘later’ which means brick. The laterite soil develops in areas with high temperature and high rainfall. These are the result of intense leaching due to tropical rains. With rain, lime and silica are leached away, and soil rich in iron oxide and aluminium compounds are left behind. Humus content of the soil is removed fast by bacteria that thrives well in high temperature. They are commonly found in Karnataka, Kerala, Tamil Nadu, Madhya Pradesh and the hilly areas of Odisha and Assam. They 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, application of manures and fertilisers are required for making the soils fertile for cultivation. Laterite soil is widely cut as bricks for use in house construction. Red laterite soils in Tamil Nadu, Andhra Pradesh and Kerala are more suitable for tree crops like cashew nut.

Arid soil

Arid soil ranges from red to brown in colour. They are generally sandy in structure and saline in nature. In some areas, the salt content is so high that common salt is obtained by evaporating the saline water. Due to the dry climate, high temperature and accelerated evaporation, they lack moisture and humus. Nitrogen is insufficient and the phosphate content is normal. Arid soil is characteristically developed in western Rajasthan, which exhibits characteristic arid topography. They are poor and contain little humus and organic matter.

Saline soil

They are also known as Usara soil. Saline soil contain a larger proportion of sodium, potassium and magnesium, and thus, they are infertile, and do not support any vegetative growth. They have more salts, largely because of dry climate and poor drainage. They occur in arid and semi-arid regions, and in waterlogged and swampy areas. Their structure ranges from sandy to loamy. They lack nitrogen and calcium. Saline soil is more widespread in western Gujarat, deltas of the eastern coast and in Sundarban areas of West Bengal. 

Peaty soil

They are found in the areas of heavy rainfall and high humidity, where there is a good growth of vegetation. Thus, a large quantity of dead organic matter accumulates in these areas, and this gives a rich humus and organic content to the soil. Organic matter in these soils may go even up to 40-50 per cent. They are normally heavy and black in colour. At many places, they are alkaline also. It occurs widely in the northern part of Bihar, southern part of Uttarakhand and the coastal areas of West Bengal, Odisha and Tamil Nadu.

Forest soil

As the name suggests, forest soil is formed in the forest areas where sufficient rainfall is available. The soil varies in structure and texture depending on the mountain environment where they are formed. They are loamy and silty on valley sides and coarse-grained in the upper slopes. In the snow-bound areas of the Himalayas, they experience denudation, and are acidic with low humus content. The soil found in the lower valleys are fertile.

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