Chapter 7 Section 3Chapter 7 Section 3

Soil ErosionSoil Erosion

• Soil EROSION or loss is important because plants do not grow as well when topsoil is lost

• Causes and effects of soil erosion – many humans activities disturb the natural BALANCE between soil production and soil erosion.

– AGRICULTURAL CULTIVATION – increased farming removes the plant cover, leaving soils open to wind and water erosion.

– FOREST HARVESTING – removes forest which increases erosion and particularly damages tropical rain forest soil.

– OVERGRAZING results when animals graze until almost all ground cover disappears.

– EXCESS SEDIMENT can damage the environment when soil erosion is severe

• Preventing soil erosion – soil must be PROTECTED

– Manage crops

• Farmers plant SHELTER BEDS of trees to break the force of the wind.

• Bare soil can be COVERED with decaying plants to hold soil in place

• Farmers can GRAZE ANIMALS on vegetation instead of plowing it under.

• With NO-TILL farming, plant stalks are left in the field to provide cover for soil.

– Reduce erosion on slopes

• CONTOUR farming reduces soil erosion by planting along the contours of slopes

• TERRACING creates steep-sided flat areas for crops on the sides of hills and mountains.

– Reduce erosion of exposed soil

• WATER is sprayed onto bare soil to reduce wind erosion

• Topsoil is replaced and TREES are planted

• WATER flow can be controlled in strip mines

• After mining, the land can be RECLAIMED