enviro

Soil as a Dynamic Ecosystem

Soil is a dynamic ecosystem with inputs, outputs, storages, and flows.

Importance of Soil

Soil is crucial for plant growth, water storage, filtration, nutrient cycling, habitat for organisms, and providing raw materials.

Soil Composition

Soil consists of mineral particles (45%), organic material (5%), water (25%), air (25%), nutrients (N, K, P), and living organisms.

Soil Profile Horizons

The soil profile consists of distinct layers: Horizon O (organic matter), Horizon A (mineral soil), Horizon B (accumulation layer), Horizon C (large rocks), Horizon R (parent rock).

Inequities in Food Systems

Food availability is unevenly distributed between MEDCs and LEDCs, leading to malnutrition and food security issues.

Food Security

Having access to sufficient, safe, and nutritious food to remain healthy.

Malnutrition

Insufficiency in one or more nutritional elements necessary for health.

The Green Revolution

A period (1960-1970) that increased crop yields through new agricultural techniques but led to biodiversity loss.

Types of Soil Degradation

Includes erosion, biological degradation, physical degradation, and chemical degradation.

Conservation Measures

Strategies to combat soil degradation, such as planting trees, using cover crops, and improving irrigation practices.

Soil Degradation

The widespread issue of soil degradation where 75% of soil has some degree of degradation due to human causes.

Types of Soil Degradation

Includes erosion (transfer of soil particles), biological degradation (loss of humus/microorganisms), physical degradation (loss of structure/permeability), and chemical degradation (acidification, decreased fertility).

Erosion

The transfer of soil particles primarily caused by water and wind.

Biological Degradation

The loss of humus and microorganisms in the soil.

Physical Degradation

The loss of soil structure and changes in permeability.

Chemical Degradation

Includes issues like acidification, decreased fertility, pH changes, and salinity.

Overgrazing

Damages vegetation, compacts soil, and increases erosion; excessive livestock feed on all vegetation.

Deforestation

Removes tree cover and increases water erosion.

Inappropriate Agricultural Practices

Includes overuse of pesticides, removal of crops at harvest, row cropping, plowing on slopes, and monocultures.

Urbanization

Paving over soil, which increases runoff and contributes to degradation.

Desertification

The gradual conversion of productive land into desert, affecting fragile ecosystems.

Consequences of Degradation

Includes desertification, erosion (sheet, gullies, wind) and overall loss of soil fertility.

Conservation Measures

Strategies such as wind reduction, soil conditioners, better cultivation techniques, improved irrigation, and not plowing unproductive soils.

Ecological Succession

Fertile soils require time to develop through succession, emphasizing the long-term process of soil formation.

Climate Change and Soil Degradation

Human activities that reduce soil fertility and increase soil erosion contribute to a negative feedback loop in climate change.

Soil as a System

Examine the soil as a dynamic ecosystem with inputs, outputs, storages, and flows.

Terrestrial Food Production Systems

Compare and contrast commercial and subsistence agricultural systems, considering socio-cultural factors.

Soil Degradation and Conservation

Investigate the causes and consequences of soil degradation and explore potential conservation techniques.

Case Study: Commercial vs. Subsistence Farming

Compare the inputs, outputs, and environmental impacts of commercial farming in the US and subsistence farming in Sub-Saharan Africa.

Deforestation and Soil Erosion

Analyze the relationship between deforestation in the Amazon Rainforest and the resulting soil erosion.

The Green Revolution in India

Evaluate the positive and negative impacts of the Green Revolution on food production and soil health.

Terraces in Asian Agriculture

Evaluate how terraces help to harness water that runs down slopes.

No-Till vs. Conventional Agriculture

Analyze the differences in soil health and water retention between no-till farming and conventional plowing.

Methodology for Case Studies

Use literature reviews, data analysis, and field studies to gather insights for case studies.

Key Questions for Soil Case Studies

Consider how soil texture affects water retention, implications of nutrient leaching, and contributions of living organisms.

Soil Texture

Soil texture refers to the proportion of sand, silt, and clay particles.

Sand

Sand particles range from 0.05 mm to 2 mm, characterized by fast-draining properties and low water retention.

Silt

Silt particles range from 0.002 mm to 0.05 mm, providing medium water retention.

Clay

Clay particles are smaller than 0.002 mm, known for being sticky, having high water retention, but low permeability.

Impact of Soil Texture on Soil Structure

Soil structure is determined by texture, affecting aeration, water retention, drainage, and root penetration.

Factors Affecting Primary Productivity

Primary productivity depends on mineral content, drainage, water retention, air spaces, biota, and the potential for retaining organic matter.

Mineral Content of Clay Soil

Clay soil can be rich in minerals but is often less fertile due to its low permeability.

Horizon O

Organic matter.

Horizon A

Mineral soil with organic matter accumulation and soil life.

Horizon B

Accumulation of Fe, clay, Al, and organic compounds.

Horizon C

Layer of large unbroken rocks that can accumulate soluble compounds.

Horizon R

Partially weathered parent rock.