Soil Degradation in India
Soil Degradation refers to the decline in soil quality and fertility, which can result from various factors such as a decrease in nutrient content, reduced population of microorganisms like earthworms, changes in soil structure, alterations in pH levels (alkalinity), and the addition of toxic elements and pollutants. Activities like animal movement or human removal of the upper layers of soil can lead to soil degradation.
Impact on Soil Resources
Soil degradation is a significant contributor to the depletion of the soil resource base in India. The extent of soil degradation varies across different regions due to factors like topography, wind patterns, precipitation, and human activities. It encompasses soil erosion, physical deterioration, chemical deterioration, and biological deterioration.
Soil Erosion
Soil erosion refers to the removal of soil at a rate higher than its natural replacement by erosional processes. While soil formation and erosion occur simultaneously, disturbances caused by natural or human factors can disrupt the balance, resulting in a net loss of soil. Human activities, such as vegetation clearance, overgrazing, and certain land drainage schemes, often accelerate natural erosion processes.
Causes
Soil erosion is influenced by factors such as topography, rainfall, wind, lack of vegetation cover, and land use practices. Rugged topography and steep slopes increase erosion rates due to the facilitation of water flow and soil movement. Climate elements like wind and rainfall act as powerful agents of soil erosion, with wind erosion being more significant in arid and semi-arid regions, while water erosion dominates regions with heavy rainfall.
- Water erosion occurs mainly in two forms: sheet erosion and gully erosion. Sheet erosion takes place when the topsoil is gradually removed, typically on level terrain following heavy rainfall. On the other hand, gully erosion occurs when runoff creates deep gullies, commonly found on steep slopes. These gullies can grow deeper with each rain, fragmenting agricultural lands and rendering them unsuitable for cultivation.
- Areas marked by a high density of deep gullies or ravines are referred to as having a “badland topography.” The Chambal Valley in Madhya Pradesh provides a notable example of gully erosion, with occurrences also documented in Tamil Nadu and West Bengal.
- Soil eroded due to erosion is transported downstream into rivers, reducing their water-carrying capacity and resulting in frequent floods and damage to agricultural lands. Coastal areas are also vulnerable to soil erosion caused by tidal waters from the Arabian Sea and the Bay of Bengal. Severe erosion of beaches along the coasts of Kerala, Tamil Nadu, Odisha, West Bengal, and Gujarat exemplify this sea-wave erosion.
- Deforestation is a significant contributor to soil erosion, particularly impacting hilly regions across the country.
- Furthermore, intensive agricultural practices that heavily rely on water and chemical fertilizers have led to waterlogging and salinity issues in various parts of the country. This has resulted in long-term soil fertility reduction, particularly evident in river valley projects that initially benefited from the Green Revolution. It’s estimated that approximately half of India’s total land area is experiencing some degree of degradation as a consequence of these factors.
Erosion Processes
Soil erosion can occur in various forms, including splash erosion (raindrop impact on bare soil), sheet erosion (removal of finer topsoil on flat land after heavy rainfall), rill erosion (formation of small channels), and gully erosion (deep gullies that render agricultural land unfit for cultivation).
Vegetation and Land Use Practices
Vegetation plays a crucial role in reducing soil erosion. Undisturbed forests have the lowest erosion rates, as vegetation intercepts and dissipates raindrops and wind energy, while plant roots physically bind soil particles, stabilizing the soil and increasing its resistance to erosion. Land use practices like agriculture and pastoral activities can contribute to erosion, particularly when soil is repeatedly tilled, left without protective vegetation cover, or subjected to overgrazing and over-irrigation.
Soil Management
Soil conservation is a systematic approach aimed at preserving soil fertility, preventing soil erosion, and restoring soil health. It encompasses various agricultural practices and management strategies designed to control soil erosion by inhibiting the detachment and transport of soil particles through air or water.
- To mitigate soil erosion, several remedial measures have been adopted, including contour bunding, contour terracing, controlled grazing, regulated forestry, cover cropping, mixed farming, and crop rotation.
- Afforestation, the process of planting trees, plays a crucial role in reducing soil erosion. It is equally important to combat indiscriminate tree felling, as it can exacerbate erosion.
- The issue of soil erosion is closely linked to flooding, which is more prevalent during the rainy season. Hence, efforts should be directed towards floodwater storage and rainwater diversion. Projects like the Ganga-Kaveri Link Canal Project, aimed at interlinking rivers, hold significant importance in this regard.
- Addressing the problem of soil erosion requires reclaiming gullies and ravines. Various schemes are being implemented, involving measures like gully mouth plugging, bund construction across gullies, gully leveling, and the planting of cover vegetation, especially in the Chambal ravines of Madhya Pradesh.
- In regions such as northeast India, the Western Ghats, and the Eastern Ghats, shifting cultivation (slash and burn) is a leading cause of soil erosion. Encouraging farmers to adopt terraced farming practices is essential. Initiatives have been launched in seven northeastern states to control shifting cultivation, focusing on rehabilitating families engaged in this practice (known as Jhumming). The goal is to replace shifting cultivation with more sustainable sedentary farming methods.
Example
An example of faulty practice is the misuse of fertilizers. In India, the recommended ratio of nitrogen, phosphorus, and potassium (NPK) fertilizer is 4:2:1. However, the actual usage often deviates from this ratio, such as in the ratio of 10:4:1. This imbalance can have detrimental effects on soil health and should be rectified.Furthermore, lands with a slope gradient of 15-25 percent are not suitable for cultivation. If such land must be used for agriculture, careful terracing should be implemented to prevent soil erosion and degradation.
Government Initiatives
The Central Soil Conservation Board, established by the Government of India, has developed various plans for soil conservation based on climate, land configuration, and social behavior. The “National project on management of soil health and fertility (NPMSF)” is a centrally sponsored scheme aiming to promote Integrated Nutrient Management (INM) and strengthen soil testing facilities. Other projects and missions, such as the National Mission on Sustainable Agriculture (NMSA) and the promotion of organic farming, also contribute to soil quality management in India.
FAQs
Q1. What are some effective methods to prevent soil erosion?
Ans. Implementing practices such as terracing, contour farming, afforestation, cover cropping, no-till farming, and the construction of windbreaks and retaining walls can significantly help prevent soil erosion.
Q2. What is meant by soil erosion?
Ans. Soil erosion refers to the process by which soil is removed or displaced from its original location due to various factors such as water, wind, or human activities, leading to the degradation of the land’s quality and fertility.
Q3. What are the main causes of soil erosion?
Ans. Soil erosion is primarily caused by factors such as water runoff, wind, human activities like deforestation, overgrazing, improper agricultural practices, construction activities, and natural disasters like floods and landslides.
Q4. What are the different types of soil erosion?
Ans. The main types of soil erosion include water erosion, wind erosion, gully erosion, and sheet erosion, each caused by different mechanisms and having varying impacts on the landscape and agricultural productivity.
Q5. What is the meaning of soil erosion?
Ans. Soil erosion refers to the wearing away of the topsoil layer by natural elements such as water and wind or by human activities, leading to the loss of fertile soil and posing a threat to agricultural productivity and the overall health of the ecosystem.
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