5.3 Soil degradation and conservation Notes

Soil degradation

Soil degradation refers to the decline in soil quality and productivity due to various natural and human-induced factors. It results in the loss of soil fertility, structure, and biodiversity, often leading to reduced agricultural productivity and environmental issues.

Causes:

1. Erosion: Wind and water erosion remove the topsoil, which is rich in nutrients. This occurs mainly due to deforestation, overgrazing, and improper land management.
2. Overgrazing: Overuse of pasture lands by livestock leads to the depletion of vegetation cover, which in turn increases the risk of soil erosion.
3. Deforestation: Removing trees and vegetation reduces the protective cover on soil, making it more susceptible to erosion and loss of nutrients.
4. Overcultivation: Intensive farming without proper crop rotation or soil-restoration practices depletes soil nutrients and weakens soil structure.
5. Salinization: The accumulation of salts in the soil, often caused by improper irrigation practices, reduces soil fertility and affects crop growth.

Soil Conservation techniques

Various strategies can be employed to preserve soil fertility and reduce erosion:

Soil Conditioners

• Organic materials:
  • Compost
  • Manure
  • Green manures (cover crops)
• Lime:
  • Helps neutralize acidic soils
  • Improves nutrient availability

Wind Reduction Techniques

1. Windbreaks: Rows of trees or shrubs planted perpendicular to prevailing winds
2. Shelter belts: Wider strips of vegetation designed to protect larger areas
3. Cover Cropping: Growing plants to protect soil from erosion.

Cultivation Techniques

1. Terracing: Creating level platforms on hillsides to reduce slope and water runoff
2. Contour ploughing: Ploughing along the contours of a hill rather than up and down
3. Strip cultivation: Alternating strips of crops with strips of protective vegetation
4. Crop Rotation: Alternating crops to maintain soil fertility.