Enviornment -BSCUV101 Soil Pollution lecture notes KVB
Page 1: What is Soil?
Definition of Soil
Soil is a thin covering over the land, a mixture of minerals, organic material, living organisms, air, and water, essential for plant growth.
Factors Contributing to Soil Formation
Mechanical Weathering: Erosion from temperature changes and physical abrasion.
Natural Elements: Wind, moving water, glaciers, and chemical weathering agents like lichens.
Climatic Factors: Climate and time influence soil development. Dry/cold climates form soil slowly, while humid/warm conditions accelerate soil formation.
Under ideal conditions, soft parent material can develop into 1 cm of soil in 15 years.
Poor conditions may require hundreds of years for hard parent material to become soil.
Page 2: Soil Structure
Soil Horizons
O Horizon: Topmost layer with organic materials (decomposed leaves, waste), typically brown or black.
A Horizon (Topsoil): Contains humus and some inorganic particles, supports most plant roots; darker and looser than deeper layers.
B Horizon (Subsoil): Contains less organic material than A Horizon.
C Horizon: Weathered parent material, no organic content. Affects soil pH and water retention.
Page 3: Causes of Soil Degradation
Main Causes
Erosion: Movement of surface litter and topsoil caused by wind and water, exacerbated by human activities (farming, deforestation).
Loss of topsoil reduces fertility and water-holding capacity, contributes to pollution.
Formation of 1 inch of topsoil can take 200-1000 years.
Conservation Techniques
Area Treatment: Land treatment for erosion control.
Drainage Line Treatment: Managing natural watercourses to prevent erosion.
Page 4: Types of Erosion
Common Forms of Erosion
Rill Erosion, Gully Erosion, Drought, Coastal Erosion
Inter-rill, Splash, and Sheet Erosion can lead to significant degradation.
Page 5: Area Treatment Techniques
Purpose & Measures
Impact Reduction: Develop vegetative cover to minimize soil displacement and enhance water infiltration.
Water Management: Store rainwater and increase soil moisture to prolong productivity.
Page 6: Drainage Line Treatment
Measures
Stop Erosion: Plug gullies, create barriers and retain groundwater.
Reduce Run-off: Treat catchments with low-cost, locally sourced methods to improve water quality.
Page 7: Gradonial Techniques
Description
Contour Trenches: Narrow trenches with bunds to collect runoff and conserve moisture, primarily on gentle slopes.
Continuous Contour Benches: Used for steep areas to combat erosion.
Page 8: Check Dams
Structures for Erosion Control
Live Check Dams: Barriers made from vegetation across gullies.
Stone and Earthen Checkbunds: Constructed to conserve water and prevent soil erosion.
Page 9: Fertilizer & Pesticide Usage
Overview
25% of crop yield links to chemical fertilizers; usage rises significantly.
Macronutrients (N, P, K) and micronutrients (B, Zn, Mn) are vital for crop production.
Page 10: Pesticide Problems
Environmental and Health Concerns
Pesticides can harm non-target species, including humans and beneficial organisms.
Persistent vs Non-Persistent: Persistent pesticides accumulate in soil and food chains, creating long-term ecological damage.
Page 11: DDT Lifecycle and Impact
DDT Statistics
Half-life varies, but can be significant (10-15 years in temperate regions).
Effectiveness diminished by resistance in pests; continues to impact ecosystems.
Page 12: Bioaccumulation and Biomagnification
Ecological Concerns
Bioaccumulation: Toxins accumulate in organisms over time.
Biomagnification: Increased concentration of toxins up the food chain, notably DDT affecting bird reproductive health.
Page 13: Resistance and Pesticide Efficacy
Issues with Insecticides
Pest resistance leads to increased pest populations after pesticide application.
Long-term pesticide exposure raises health risks.
Page 14: Organic Farming Solutions
Advantages
Reduces reliance on chemicals, enhances soil organic matter and reduces erosion.
Crop rotation improves fertility and pest control.
Page 15: Integrated Pest Management (IPM)
Definition and Benefits
IPM combines ecological understanding to minimize pesticide use, introducing biopesticides.
Examples: Biopesticides from microbial or botanical sources.
Page 16: Salt Accumulation Issues
Salinization
Excess salts in irrigation water stunt plant growth, can be mitigated by flushing with water.
Page 17: Water Quality Parameters
Water Quality Assessment
Classification of water quality based on parameters (EC, SAR, ESP).
Page 18: Sustainable Farming Practices
Long-Term Solutions
Must address water logging and salt accumulation to prevent soil degradation and improve productivity.
Page 19: Pollution from Organic Wastes
Impact on Water Quality
Organic wastes reduce oxygen in water, leading to anoxic zones harmful to aquatic life.
Page 20: Pollution Control Measures
Treatment Solutions
Implementing sewage treatment plants to reduce biological oxygen demand (BOD) before water discharge.