Grade 8 Chapter 12-1 Conserving Land and Soil. Objectives Describe how people use land Discuss the kinds of problems that occur when soil is not properly.

Grade 8 Chapter 12-1

Conserving Land and Soil

ObjectivesDescribe how people use landDiscuss the kinds of problems that occur when soil is not properly managedDiscuss the nitrogen cycle

Types of land UseAgriculture

Less than 1/3 of the lands surface is tillable land The rest is too wet, too dry, too salty,or too mountainous

New farmland is created by Draining wetlands, Clearing forests Irrigating deserts

Agriculture

2nd Type of Land UseDevelopment

First occurred near water or fertile soils, later moved to other areas.The construction of Homes , roads, bridges, and other structures

Land Use Development

3rd Type of Land useMining – the removal of nonrenewable resources such as iron, copper and coal from the landStrip mining involves removing a strip of land to obtain the minerals and then replacing the strip.

May cause erosion as materials are more exposed to the elementsStrip mined area may remain barren for years

Underground Mining Deep deposits.Talus may cause pollution due to leaching.

Mining

Restoring the landLand reclamation – the process of restoring the land to a more natural productive state.More expensive than maintaining the land.

Protecting the soilLayers of soil

Topsoil Litter (humus) Mineral material Contains plant nutrients Takes many years to replace

Subsoil Weathered rock material

Parent Material ( Bed Rock) Cannot support plant life

When soil is not protected it may erode, become a desert or be depleted

ErosionProcess by which wind, water, gravity or ice moves particles of rock or soil. Rate of erosion is effected by soil management practices and Land use practices

Planting cover plantsMiningAgriculture activitiesLand use

Erosion

DesertificationThe advance of desert-like conditions into areas that previously were fertile.Caused by

OvergrazingPoor Farming practicesExcessive cutting of fire wood

desertification

Nutrient DepletionThe removal of nutrients from soils by plants which results in lower soil fertility.Nutrient depletion can be prevented by

Leaving fields fallowLeaving crop residue on fieldsCrop rotation

Nitrogen CycleThe process by which nitrogen is removed from the atmosphere, fixed in the soil by bacteria, incorporated into other living things, and then released back into the atmosphere.

Nitrogen Cycle

ReviewWhat are three ways people use land?What are three problems that can occur when soil is not managed properly?Why is it important to protect the topsoilDescribe two methods for reducing erosionDescribe the Nitrogen cycle