Soil, Food Production, and Environmental Impact

Importance of Soil

Soil supports plant growth, holds water, recycles nutrients, and is essential for sustainable agriculture.

O Horizon

Organic matter (leaves, decomposed material)

A Horizon

Topsoil; rich in organic material and roots

B Horizon

Subsoil; accumulation of minerals

C Horizon

Weathered parent rock

Soil Erosion Problems

Reduces fertility and increases sedimentation in waterways.

Conservation Farming Methods

Crop rotation, contour farming, terracing, low/no-till farming, cover crops.

Irrigation Issues

Can cause salinization (salt buildup) and water waste.

Fertilizer Use

Boosts plant growth by providing nutrients, especially nitrogen, phosphorus, and potassium.

Limiting Factor

The scarcest nutrient limits growth (often nitrogen).

Problems with Fertilizer

Runoff leads to eutrophication (algal blooms, dead zones), groundwater contamination.

Haber-Bosch Process

Industrial method to synthesize ammonia for fertilizer from atmospheric nitrogen.

Conventional Agriculture

Uses synthetic chemicals, GMOs, monocultures.

Organic Agriculture

Avoids synthetic inputs, uses natural fertilizers, crop diversity.

Green Revolution Accomplishments

High-yield crops, reduced hunger in many areas.

Future Problems in Agriculture

Dependency on fossil fuels, soil depletion, pollution, inequality.

Environmental Impact of Agriculture

Fertilizer runoff, water use, biodiversity loss.

Locavore Movement

Supports eating local to reduce food miles, support local economy, and preserve seasonal eating.

Arguments For Local Food

Lower emissions, fresher food, supports local farmers.

Arguments Against Local Food

Not always more sustainable (e.g., heated greenhouses), can be more expensive.

Food Miles

Distance food travels.

Life Cycle Assessment

Includes total environmental cost (production, transport, storage, waste).

Environmental Impact of Meat

Beef and lamb have high greenhouse gas emissions and land use; poultry and eggs are lower.

Ecological Principles

Energy loss up trophic levels makes meat less efficient than plant foods.

Modern Challenges in Fisheries

Overfishing, bycatch, habitat destruction (e.g., bottom-trawling), fish farming impacts.

Cod Example

Overfishing led to collapse, affected ecosystems.

Trophic Cascade

Removal of top predators alters ecosystem balance.

Solutions for Fisheries

Turtle-excluder devices, sustainable fishing certifications (e.g., MSC), aquaculture improvements.

What Are GE Foods?

Contain transgenes from other species (e.g., bacteria in Bt corn).

Bt Transgene

Makes crops insect-resistant by producing a natural pesticide.

Roundup Ready Crops

Tolerate glyphosate herbicide, simplifying weed control.

Pros of GE Foods

Pest resistance, increased yield, reduced chemical use.

Cons of GE Foods

Environmental risks (e.g., superweeds), ethical concerns, biodiversity.

Labeling of GE Foods

Controversial; many countries require it, some don't.

GE Salmon

Grows faster; first GE animal approved for consumption.

Finding Credible Info

Use peer-reviewed sources, government databases, reputable organizations.

Impact of Food Waste

Wastes resources (water, land, emissions).

Most-Wasted Categories

Fruits, vegetables, bakery items.

Biggest Waste Sources

Consumer level (households), followed by retailers.

Reducing Food Waste

Meal planning, buying 'ugly' produce, composting.

Significance & p-values

A p-value < 0.05 suggests a statistically significant difference—not likely due to chance.

Environmental Impact Comparisons

Always ask 'per what?' (e.g., per kg food vs. per hectare)—it affects conclusions.

Scientific Literature

Use databases (e.g., PubMed, ScienceDirect), check methodology, source credibility.

Organic Certification

Must meet USDA/NOP standards (no synthetic pesticides, GMOs, etc.)

Natural Label

Not regulated.

No Hormone Label

Only meaningful for animals that typically receive them (e.g., beef, not poultry).

Trends in Organic Purchases

Organic purchases increasing, especially among younger and health-conscious consumers.