Major Causes for Land Degradation

Land degradation refers to the deterioration of soil quality resulting from its inappropriate utilization, often for agricultural, pastoral, industrial, or urban purposes.
This issue is a significant global environmental concern and can be further intensified by the impacts of climate change.
It includes physical aspects such as soil erosion, chemical factors like salinity, alkalinity, and pollution, as well as biological deterioration involving the degradation of vegetative cover.

Table of Contents

MAJOR CAUSES OF LAND DEGRADATION

DEFORESTATION

Deforestation is the consequence of intensified pressure on forested lands and resources due to the population explosion.
This phenomenon exacerbates soil erosion, a form of soil degradation.
The roots of trees and plants play a crucial role in binding soil particles and regulating water flow, providing protection against erosion.
However, deforestation leaves the soil exposed to the risks of wind and water erosion.
Significant soil damage in regions like the Shiwalik range, the Chos of Punjab, and the ravines of the Chambal valley can be attributed to large-scale deforestation.
The major causes of deforestation include shifting cultivation, where land is periodically cleared, burned, and used for crops before being abandoned; development projects and mining, leading to widespread forest loss; the demand for commodities like cocoa, coffee, tea, sugar, palm oil, rubber, contributing to deforestation in tropical rainforests; and the extraction of raw materials for various industries.
Industries, utilizing wood as a raw material for products like paper, plywood, furniture, and others, also contribute to deforestation.
Additionally, deforestation stems from various factors such as overgrazing, agriculture, mining, urbanization, floods, fires, pests, diseases, as well as defense and communication activities.
The effects of deforestation are profound, resulting in a reduction of closed forests and an increase in degraded ones.
Forests play a crucial role in recycling moisture through transpiration, which is disrupted by deforestation, leading to lowered groundwater levels and a long-term decrease in precipitation.
This disruption in the natural water reuse cycle contributes to rapid runoff, impacting biota, neighboring ecosystems, soil erosion, land degradation, alteration of groundwater channels, and environmental pollution.
Deforestation, therefore, has far-reaching consequences, including scarcity of resources and alterations in the delicate balance of ecosystems.

OVERGRAZING

In the rainy season, abundant vegetation provides ample fodder for animals.
However, during the dry period, a shortage of fodder arises, prompting animals to graze grass to the ground and tear it out by the roots. This extensive grazing leads to the loss of soil structure, making it susceptible to erosion when rains occur.
Additionally, the hoofs of animals pulverize the soil, reducing it to fine particles.
This process proves detrimental to the topsoil, especially when heavy showers fall on it.
The combined effects of overgrazing and soil pulverization contribute to soil erosion, a common sight in hilly areas.
The loss of vegetation cover, coupled with the disruption of soil structure, intensifies the vulnerability of the soil to erosion, impacting the overall health and stability of the ecosystem.

SOIL SALINITY AND ALKALINITY

In saline and alkaline soils, the topsoil becomes impregnated with saline and alkaline efflorescences, characterized by the accumulation of salt particles.
The origin of these salts is attributed to undecomposed rock fragments, which, upon weathering, release sodium, magnesium, calcium salts, and sulphurous acid. Some of these salts are transported in solution by rivers.
In areas with a low water table, salts may percolate into the subsoil, and in well-drained regions, they are carried away by flowing water.
However, poor drainage can lead to the stagnation of water with high salt concentration, causing the deposition of salts in the topsoil upon evaporation.
In regions with a high sub-soil water table, injurious salts may be drawn up from below through capillary action during the dry season’s evaporation.
Canal irrigated areas, where excessive water is often applied, contribute to the rise of the groundwater level.
This, in turn, leads to the appearance of saline and alkaline efflorescences on the soil surface, primarily composed of sodium, calcium, and magnesium salts, facilitated by capillary action.
Vast areas in states like Uttar Pradesh, Punjab, Haryana, arid regions of Rajasthan, and semi-arid areas of Maharashtra, Gujarat, Andhra Pradesh, Telangana, and Karnataka face challenges associated with salinity and alkalinity due to over-irrigation.
While projects like the Indira Gandhi canal in Rajasthan have transformed sandy deserts into productive granaries, they have also given rise to significant problems related to salinity and alkalinity in these areas.
Balancing irrigation practices and implementing effective drainage systems are crucial for managing and mitigating the adverse impacts of salt accumulation in the soil.

DESERTIFICATION

Desertification refers to the expansion of desert-like conditions in arid or semi-arid areas, resulting from both human activities and climatic changes.
A significant portion of the arid and semi-arid region situated between the Indus and the Aravalli range is experiencing the encroachment of desert conditions.
Wind erosion plays a pivotal role in desert soils, causing substantial soil loss.
The sand transported by the wind settles on adjacent fertile lands, diminishing their fertility.
Gradually, these once fertile lands begin to blend with the advancing desert, exacerbating the desertification process.
Alarming estimates suggest that the Thar Desert is advancing at a rate of approximately 0.5 km per year.
The process of desertification can be attributed to various factors, including uncontrolled grazing, indiscriminate deforestation, and the expanding human population.
Additionally, climate change has played a role in fostering the spread of deserts, contributing to the challenging conditions faced by these arid and semi-arid regions.
The combined impact of these factors poses a significant threat to the ecological balance and sustainability of the affected areas.
Addressing desertification requires coordinated efforts in sustainable land management, conservation, and mitigating the adverse effects of climate change.

WATER LOGGING

The formation of flat surfaces and depressions contributes to the issue of waterlogging, where soils become saturated with water either from rainfall or leakage from various water sources.
In India, the extent of waterlogged soils is substantial, covering about 12 million hectares, with half located along the coast and the other half inland. Waterlogging is identified as a primary cause of salinity in these areas.
Addressing the challenge of waterlogging necessitates the implementation of proper drainage schemes. Two fundamental methods are employed for removing excess water from waterlogged soils: surface drainage and vertical drainage.

Surface Drainage:

Surface drainage involves the disposal of excess water across the ground surface through an open drainage system equipped with a suitable outlet. This method is essential for preventing the accumulation of water in depressions and flat surfaces.

Vertical Drainage:

Vertical drainage refers to the extraction of underlying water through bores or wells. This technique is particularly effective in regions like the Indo-Gangetic plain, where the pumped water is utilized for irrigating neighboring areas. Vertical drainage helps in lowering the water table and mitigating waterlogging issues.
The proper layout and implementation of drainage schemes are crucial in overcoming the challenges posed by waterlogging. By employing surface and vertical drainage methods strategically, it becomes possible to manage and alleviate the adverse effects of waterlogged soils, ensuring improved agricultural productivity and preventing the associated problems such as salinity.

FAQs – Major Causes for Land Degradation:

1. What is land degradation, and why is it a global environmental concern?

A: Land degradation refers to the deterioration of soil quality due to inappropriate use for various purposes. It is a significant global environmental concern, further intensified by the impacts of climate change.

2. How does deforestation contribute to land degradation?

A: Deforestation, driven by population pressure, leads to soil erosion. The absence of trees and plants reduces soil stability, making it vulnerable to wind and water erosion.

3. What are the major causes of deforestation?

A: Deforestation is caused by shifting cultivation, development projects, mining, demand for commodities like cocoa, coffee, tea, sugar, palm oil, rubber, and extraction of raw materials by industries. Overgrazing, agriculture, mining, urbanization, floods, fires, pests, diseases, defense, and communication activities also contribute.

4. What are the effects of deforestation on ecosystems and water cycles?

A: Deforestation results in reduced closed forests, increased degradation, and disruptions in the natural water reuse cycle. This leads to lowered groundwater levels, decreased precipitation, and impacts on biota, neighboring ecosystems, soil erosion, land degradation, groundwater channels, and environmental pollution.

5. How does overgrazing contribute to soil degradation?

A: Overgrazing occurs when animals deplete vegetation during dry periods, leading to the loss of soil structure. Animal hoofs pulverize the soil, making it susceptible to erosion during heavy rainfall.

6. What is the relationship between soil salinity/alkalinity and land degradation?

A: Saline and alkaline soils result from the impregnation of topsoil with salt particles. The causes include undecomposed rock fragments, river transportation of salts, poor drainage leading to salt accumulation, and over-irrigation in canal-irrigated areas.

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Major Causes for Land Degradation – Deforestation, Soil Salinity and Soil Alkalinity, Desertification, Waterlogging – UPSC Environment Notes