Lesson Overview

1. Lesson Overview 6.2 Using Resources Wisely

2. Soil Erosion • Soil erosion is the removal of soil by water or wind. • The dust bowl of the 1930s was caused, in part, by conversion of prairie land to cropland in ways that left soil vulnerable to erosion.

3. Soil Erosion • Desertification • Farmland desert. • Occurs in parts of the world with dry climates, a combination of farming, overgrazing, seasonal drought, and climate change • ~ 40% of Earth’s land is considered at risk for desertification.

4. Soil Erosion • Deforestation- loss of forests • -negative effect on soil quality • Healthy forests • hold soil in place, protect the quality of fresh water, absorb carbon dioxide, and help moderate local climate. • In some places, forests don’t grow back at all after logging. This is why old-growth forests are usually considered nonrenewable resources.

5. Soil Use and Sustainability • Crop rotation—planting different crops at different seasons- prevents erosion and nutrient loss. • Contour plowing involves planting fields of crops across, instead of down, the slope of the land. • reduces water runoff & erosion. • Terracing—shaping the land to create level “steps”—also helps hold water and soil.

6. Water Pollution • A pollutant is a harmful material that can enter the biosphere. • point source pollution-Pollutants that enter from a single source • Ex: factory or an oil spill • nonpoint source pollution- Pollutants that enter water supplies from many smaller sources • Ex grease and oil washed off streets by rain or the chemicals released into the air by factories and automobiles