The Hindu Editorial Analysis- 5th December 2022 | Current Affairs & Hindu Analysis: Daily, Weekly & Monthly - UPSC PDF Download

Context

World Soil Day (WSD) 2022, annually observed on December 5, aligns with this. WSD 2022, with its guiding theme, ‘Soils: Where food begins’, is a means to raise awareness on the importance of maintaining healthy soils, ecosystems and human well-being by addressing the growing challenges in soil management, encouraging societies to improve soil health, and advocating the sustainable management of soil. 

Key Points

• It was recommended by the International Union of Soil Sciences (IUSS) in 2002. The Food and Agriculture Organisation (FAO) has supported the formal establishment of WSD as a global awareness-raising platform under the leadership of the Kingdom of Thailand within the framework of the Global Soil Partnership.
• 5^th December 2014 was designated as the first official WSD by the UN General Assembly (UNGA).
  • 5^th December was chosen because it corresponds with the official birthday of H.M. King Bhumibol Adulyadej, the King of Thailand, who officially sanctioned the event.
• FAO gives two awards in line with this day:
  • The King Bhumibol World Soil Day Award: An annual award that honours individuals, communities, organizations and countries that organized remarkable and engaging World Soil Day activities or campaigns in the previous year.
  • The Glinka World Soil Prize: An annual award for dynamic change-makers dedicated to solving one of our world’s most pressing environmental issues: soil degradation. It honors individuals and organizations whose leadership and activities have contributed, or are still contributing to the promotion of sustainable soil management and the protection of soil resources.

Soil Erosion

Erosion is a comprehensive natural process of detachment and removal of loosened Rock materials and soils by exogenetic processes without being interfered with by human activity is also called as geological erosion

Slow removal of soil is a part of the natural geological process of denudation and is both inevitable and universal.

Accelerated erosion refers to the increased rate of erosion caused by various land-use changes affected by man thus soil erosion normally means accelerated erosion which is also called as man-induced erosion 

Soil erosion is an extreme form of soil degradation in which the natural geomorphological process accelerated so that soil is removed at a rate of ten and sometimes several thousand times faster than is the case under the condition of natural vegetation and much faster than the rate at which new soil forms

Accelerated soil erosion or man-induced soil erosion is mostly operative in the humid climate regions where extensive forest clearance, grassland remover, and extensive overgrazing and trampling by livestock have been practiced by the man at an alarming rate

Soil erosion involves mainly two processes viz. 

1. loosening and detachment of soil particles from the soil mass and 
2. removal and transport of the detached soil particles downslope human activities have largely modified and changed the land use pattern but some distinction 

L. D. Meyer and W. H. Wischmeier stated that the detachability of soil particles from soil mass is a crucial factor for soil erosion. The detachability largely depends on grains-size or the size and the cohesiveness of the particles. The detachment of particles having a grain size of above 0.2 mm requires more force provided by the velocity of moving water. The required critical velocity to the detach soil particles increases with an increase in the grain size above 0.20 mm 

Morisawa (1968) has identified two major independent factors which control the rate and type of soil erosion occurring on hill slopes i.e. climate and geology.

Soil erosion and land degradation together, constitute one of the major problems that disturb the ecological balance of the world. The rapid increase in the human population has placed a great strain on the land and soil resources resulting in land degradation and soil erosion. On a worldwide basis, more than 4.85 billion acres (1.96 billion hectares) or 17% of the earth under vegetation has been degraded by humans to various extents.

Types of Soil Erosion

Soil erosion is classified on the basis of the physical agent responsible for erosion. The various types of soil erosion are consequently referred to as:

(a) Water erosion
(b) Wind erosion

(a) Water erosion

Running water is one of the main agents, which carries away soil particles. Soil erosion by water occurs by means of raindrops, waves, or ice. Soil erosion by water is termed differently according to the intensity and nature of erosion.

(i)Raindrop erosion (ii) Sheet erosion (iii) Rill erosion (iv) Steam banks erosion (v) Erosion due to landslides (vi) Coastal erosion.

Raindrop erosion

• Raindrops behave like tiny bombs when falling on exposed soil, displace soil particles and destroy soil structure.
• Average size of a raindrop is approximately 5 mm in diameter falling through the air hits the soil at a velocity of 32 km/hr.
• Presence of vegetation on land prevents raindrops from falling directly on the soil thus erosion of soil in areas covered by vegetation is prevented.

Sheet erosion

• The detachment and transportation of soil particles by flowing rainwater is called sheet or wash off erosion.
• This is a very slow process and often remain unnoticed.

Rill erosion

• In rill erosion finger like rills appear on the cultivated land after it has undergone sheet erosion.
• These rills are usually smoothened out every year while forming.
• Each year the rills slowly increase in number become wider and deeper.
• When rills increase in size, they are called gullies. Ravines are deep gullies.

Streambank erosion

• The erosion of soil from the banks (shores) of the streams or rivers due to the flowing water is called bank erosion.

Landslide

• A sudden mass movement of soil is called a landslide. Landslides occur due to instability or loss of balance of land mass with respect to gravity.

Coastal erosion

• Coastal erosion of soil occurs along seashores. It is caused by the wave action of the sea and the inward movement of the sea into the land.

Consequences of water erosion

• Erosion removes the most fertile part of the soil. The less fertile subsoil is left.
• The fine particles of the topsoil which contain the bulk of nutrients and organic matter needed by the plants are lost from soil erosion.
• Erosion may result in the removal of seeds or seedlings so that the soil becomes bare. Bare soil is more vulnerable to erosion both by wind and water.
• Removal of seeds and seedlings reduces the ability of soil to store water.
• Sheet, rill, gully, and stream bank erosion also cause siltation of rivers, streams, and fields.
• Deposition of silt results in damage of crops and pastures, and sedimentation of water bodies like streams, dams, reservoirs, etc.
• Sedimentation of water bodies deteriorates water quality and damage aquatic habitats and organisms.
• Coastal erosion causes the adjourning land to become covered by sand.

(b) Wind erosion

Soil erosion by wind is more common in areas where the natural vegetation has been destroyed. Such conditions occur mainly in arid and dry areas along the sandy shores of oceans, lakes, and rivers.

The loose soil particles are blown and transported from wind by following three ways:

(i) Siltation: blown by the wind in a series of short bounces.
(ii) Suspension: transported over long distances in the form of suspended particles.
(iii) Surface creep: transported at ground level by high-velocity winds.

Consequences of wind erosion

• Wind erosion removes the finer soil material including organic matter, clay, and slit, in a suspension (colloidal) form and leaving behind coarser, less fertile material.
• The productive capacity of the soil is lost as most of the plant nutrients which remain attached smaller colloidal soil fraction are lost.
• Wind erosion also damages roads and fertile agricultural fields by depositing large quantities of air blown soil particles.

Soil Erosion caused by Human Activity

Certain human activities accelerate soil erosion.

• Deforestation
• Farming
• Mining
• Developmental work, human settlements, and transport

Deforestation:

Deforestation includes cutting and felling of trees, removal of forest litter. Browsing and trampling by livestock, forest fires, also leads to cause deforestation, etc. Deforestation leads to erosion. Deforestation further leads to land degradation, nutrient, and the disruption of the delicate soil-plant relationship.

Farming:

Agriculture is a major human activity that causes soil erosion. Crops are grown, harvested, land re ploughed, exposed to wind and rain intermittently. All this prevents replenishment of moisture. Agriculture also causes the worst type of soil erosion on farmland in the form of wash off or sheet erosion. On the arid and semiarid areas, sand blows and sand shifts act in a similar fashion as sheet erosion does, where water is the chief agent. Consequently, a creeping effect of desertification sets in, and the fertility of the land is lost progressively.

The following agricultural practices can lead to accelerated soil erosion:

1. Tilling or ploughing increases the chances of erosion because it disturbs the natural soil surface and protective vegetation.
2. Continuous cropping: Continuous cropping of the same land and extending of cultivation of marginal and sub-marginal lands encourages soil erosion.
3. Cultivation on mountain slopes: Cultivation on mountain slopes without appropriate land treatment measures such as bounding, terracing, and trenching cause soil erosion and loss of soil nutrients.
4. Monoculture: Monoculture refers to the practice of planting of the same variety of crops in the field. Monoculture practices can lead to soil erosion in three ways.
   • (i) A monoculture crop is harvested all at one time, which leaves the entire fields bare exposing it to both water and wind.
   • (ii) Without vegetation natural rainfall is not retained by the soil and flows rapidly over the surface rather than into the ground. It also carries away the topsoil which results in soil erosion and degradation.
   • (iii) In the event any disease or pest invades the field, the entire crop is usually wiped out leaving the bare soil susceptible to water and wind.
5. Overgrazing: It means too many animals are allowed to feed on a piece of grassland. Trampling and grazing by cattle destroy the vegetation of the area. In the absence of adequate vegetative cover, the land becomes highly susceptible to both wind and water erosion.
6. Economic activities: Soil erosion also occurs due to economic activities. The extraction of useful natural resources such as metals, minerals, and fossil fuels, etc., from the land causes serious disturbance to the land leading to soil erosion and drastic changes in the landscape.
7. Developmental activities: Soil erosion may also occur because of various developmental activities such as housing, transport, communication, recreation, etc. Building construction also promotes soil erosion because accelerated soil erosion takes place during the construction of houses, roads, rail tracks, etc. The construction of such facilities causes massive disturbance to the land, resulting in soil erosion and disruption of the natural drainage system.

Consequences of Soil Erosion:

1. The fine particles of the topsoil which contain the bulk of nutrients and organic matter needed by the plants are lost from soil erosion. Wind erosion removes the finer soil material including organic matter, clay, and slit, in a suspension (colloidal) form and leaving behind coarser, less fertile material.
2. Erosion may result in the removal of seeds or seedlings so that the soil becomes bare. Bare soil is more vulnerable to erosion both by wind and water. Removal of seeds and seedlings reduces the ability of soil to store water.
3. Sheet, rill, gully, and stream bank erosion also causes siltation of rivers, streams, and fields. Deposition of silt results in damage of crops and pastures, and sedimentation of water bodies like streams, dams, reservoirs, etc. Sedimentation of water bodies deteriorates water quality and damage aquatic habitats and organisms.
4. Gully erosion also results in the loss of large volumes of soil. Wider deep gullies sometimes reach 30 m and thus severely limit land use. Large gullies disrupt normal farm operations.
5. Streambank erosion not only causes loss of land but also changes the course of a river or stream. Stream bank erosion also damages public roads. Wind erosion also damages roads and fertile agricultural fields by depositing large quantities of air blown soil particles.
6. The mass movement of land or landslides also inhibits farm production and land use. It also causes mortality in animals and humans.
7. Coastal erosion causes the adjourning land to become covered by sand.

Prevention of Soil Erosion

• It is essential to retain vegetation cover that soil is not exposed to rain, vegetation cover is important because roots of plants hold soil particles together. Plants intercept rainfall and protect soil from direct impact of raindrops.
• Cattle grazing should be controlled.
• Crop rotation and keeping the land fallow (not planting anything in the soil for some time) should be adopted
• Vegetation and soil management should be improved in order to increase soil organic matter.
• To prevent stream bank erosion runoff water should be stored in the catchment for as possible by maintaining vegetation cover and as by constructing dams for storing water
• For the prevention or reduction of coastal erosion, protective vegetation along the beaches should be re-established. The best method of controlling coastal dune erosion is not to disturb the dunes and the coastal system. Further, the construction of buildings and other development should be located behind the dune system.
• The vegetation cover over sandy soils should be kept above 30%.Access of wind to the soil should be controlled by leaving the stubble or mulch on the soil. (Stubble is the remains of the crop left after harvesting).
• Wind speed can be broken or controlled by planting trees in form of a shelter belt.

What are the Initiatives to Improve Soil Health?

• The Nutrient Based Subsidy (NBS) Scheme
• Paramparagat Krishi Vikas Yojana
• Carbon Farming
• Soil Health Card Scheme
• Organic Farming
• Fertilizer Self-Sufficiency
• Digital Agriculture