Conservation of Water and Soil: quick revision, 16 bites

Limited Resources That Seem Everywhere

Abundant on Earth, scarce when usable.

Water and soil look plentiful, but only a **small, slowly-renewing portion** is actually usable — and it can be lost far faster than nature replaces it.

Takeaway. Conservation means using these resources wisely so they are not used up before nature can replace them.

What Conservation Really Means

Not 'save less' — 'use wisely'.

Takeaway. Conservation is about smart, careful use — not stopping use altogether.

Where Earth's Water Actually Is

97% of Earth's water? Not for drinking.

Takeaway. The tiny share of usable freshwater must serve a huge, growing global population.

Why Growing Populations Strain Water

More people, same water supply.

The total freshwater in a region stays roughly the same, but **more people need more water** for drinking, cooking, farming, and industry.

Takeaway. Population growth increases demand on a fixed freshwater supply — making conservation essential.

Saving Water at Home

Two habits, big savings.

Takeaway. Small daily habits at home add up to large water savings over time.

Drip vs Flood Irrigation

Drop by drop beats flooding.

Takeaway. Drip irrigation targets roots directly, cutting the evaporation and runoff that flood irrigation wastes.

Rainwater Harvesting in Cities

Catch the rain before it runs off.

Rain falling on rooftops and roads normally runs off and is wasted. **Rainwater harvesting** captures it for later use or lets it soak in to recharge groundwater.

Takeaway. Harvesting rain turns wasted runoff into a stored, usable water supply.

What Soil Is Made Of

Soil is not just 'dirt'.

Takeaway. Soil is a complex living mixture — essential for growing crops.

Soil Forms Extremely Slowly

1 cm of soil = up to 1,000 years.

Fertile soil forms through the **extremely slow weathering of rock** into tiny particles.

Takeaway. Because soil forms so slowly, protecting it is far easier than replacing it.

Soil Erosion Defined

Topsoil washed or blown away.

Takeaway. Erosion strips away the nutrient-rich topsoil that crops depend on.

Main Causes of Soil Erosion

Three ways farmers lose topsoil.

Takeaway. Anything that removes plant cover exposes topsoil to being washed or blown away.

Why Deforestation Causes Erosion

No roots, no grip on soil.

Takeaway. Deforestation removes the root structure that holds soil in place.

How Erosion Hurts Crop Yields

Erosion steals the nutrients.

Takeaway. Less fertile soil after erosion means weaker crops and smaller harvests over time.

Four Ways to Conserve Soil

Four farming methods that save soil.

Takeaway. Each method either slows water, blocks wind, or anchors soil with roots.

How Terrace Farming Works

Steps that stop soil from sliding.

Takeaway. Terraces slow water flow, so it cannot carry topsoil downhill.

Quick Revision: Key Terms

Match the term, score the mark.

Takeaway. Know these six terms — they cover most exam questions on this chapter.