Soils Degradation: Impact of Erosion on Fertility

Soil degradation is defined as a decline in soil fertility, marked by a reduction in nutritional status and soil depth due to erosion and misuse. This degradation is identified as a key factor driving the depletion of the country’s soil resource base. The extent of soil degradation varies across different regions, influenced by local topography, wind velocity, and rainfall levels.

Soil erosion is a significant contributor to soil degradation. It occurs when topsoil is removed or displaced by natural forces such as wind, water, or human activities like deforestation or improper land use practices.

Soil Erosion: Human Impact on Soil Balance

• Meaning: Soil Degradation, described as the destruction of soil cover, results from an imbalance between soil-forming and erosional processes, intensified by natural or human factors such as deforestation and overuse of land for settlement, cultivation, and grazing. 
• Disruption of Equilibrium in Soil Particle Balance: The rate of removal of fine particles from the surface is the same as the rate of addition of particles to the soil layer
  • Sometimes, this balance is disturbed by natural or human factors, leading to a greater rate of removal of soil. 

Soil Erosion

• Human-Induced Soil Erosion: Human activities too are responsible for Soil Degradation to a great extent.
  • As the human population increases, the demand on the land also increases. 
  • Forest and other natural vegetation is removed for human settlement, for cultivation, for grazing animal and for various other needs.
• The Dynamics of Erosion: It varies with regional conditions;
  • Wind Erosion: Wind plays a significant role in arid areas and semi-arid regions.
  • Water Erosion:  This occurs mostly  in regions with heavy rainfall and steep slopes.
    • Erosion by running water is more significant.
    • Water erosion which is more serious and occurs extensively in different parts of India, takes place mainly in the form of sheet and gully erosion
    • Sheet erosion: Discreetly removes the fertile topsoil \.
      • Sheet erosion takes place on level lands after a heavy shower.
      • It removes the finer and more fertile topsoil, hence it is harmful.
    • Gully Erosion: Visibly fragments agricultural lands, forming ‘badland topography’ with ravines.
      • It  is common on steep slopes.
      • Gullies cut agricultural lands into small fragments and make them unfit for cultivation.
      • Ravines in the Chambal basin are widespread, It is also found in Tamil Nadu, and West Bengal, costing India around 8,000 hectares of land annually.

Implications of Soil Erosion: Threats to Agriculture and Urgent Conservation 

• Impact on Agriculture: Soil erosion not only jeopardises agriculture but also escalates issues like river siltation.
  • It leads to reduced carrying capacity of rivers and frequent floods which damages agricultural lands.
• Loss of Root Protection and Humus: Deforestation exacerbates Soil Degradation, especially in hilly regions, by removing the root-bound protection and humus supply to the soil.
• Loss of Soil Fertility: Over-irrigation in arable lands induces soil salinity as salt from lower profiles resurfaces, diminishing soil fertility. 
  • Reliance on chemical fertilisers without organic manures hardens the soil and declines its fertility over time.
  • Difficulty observed in command areas of river valley projects post the Green Revolution.
• Soil Degradation in India: With nearly half of India’s total land facing degradation, the nation confronts a loss of millions of tonnes of soil and nutrients annually, adversely impacting national productivity. 
• Urgent Call for Soil Conservation: The stark data necessitates immediate initiatives for soil reclamation and conservation to abate the detrimental cycle of soil degradation and ensure sustainable agricultural productivity.

Terrace Farming

Soil Conservation: The Essence of Soil Conservation

• Meaning: Soil conservation is a process of maintaining soil fertility and preventing erosion and emerges as a human-centric remedy to the degradation induced by human activities.

Remedial Measures: Practical Solutions for Conservation 

• Minimizing Cultivation on Steep Slopes: The initial step entails restricting cultivation on sloped lands with a gradient of 15-25 per cent, instead of encouraging terrace farming (Refer Figure 6.7).
• Sustainable Farming Practices through Community Education: Over-grazing and shifting cultivation have led to erosion, necessitating education for villagers on sustainable practices.
• Implementing Diverse Remedial Measures: Several remedial measures, like contour bunding, contour terracing, regulated forestry, controlled grazing, cover cropping, mixed farming, and crop rotation, are advocated to mitigate Soil Degradation. 
• Combatting Gully Erosion: To address gully erosion, terracing and the construction of check dams are suggested.
  • Along with efforts to control the extension of gullies through plugging, terracing, or cover vegetation planting.
• Protecting Arid Lands: In arid regions, shielding cultivable lands from sand dunes through shelterbelts of trees, agro-forestry, and converting non-arable lands into pastures are recommended. 
  • Exemplifying this, the Central Arid Zone Research Institute (CAZRI) has experimented with stabilising sand dunes in western Rajasthan.

Conclusion

• Soil, a pivotal entity, nurtures diverse life forms and significantly contributes to our daily sustenance. 
• Its formation, influenced by natural and human-induced factors, reveals a complex structure that varies across regions. 
• Unveiling the intricacies of soil through careful study and classification paves the way for sustainable practices, ensuring its preservation and continued fertility for future generations. 
• Hence, a profound understanding of soil is imperative for harmonising human activities with nature’s delicate balance.