Sustainable Land Sustainable Land UseUseSC.912.L.17.12SC.912.L.17.12

Land ResourcesLand Resources

Land is a resource that provides space for Land is a resource that provides space for human communities and raw materials for human communities and raw materials for industryindustry

Land also includes the soils in which crops are Land also includes the soils in which crops are growngrown

If managed properly, soil is a nenewable If managed properly, soil is a nenewable resourceresource

Soil can be permanently damaged if it is Soil can be permanently damaged if it is mismanagedmismanaged

TopsoilTopsoil

Food crops grow best in fertile soil, which is a Food crops grow best in fertile soil, which is a mixture of sand, clay, rock particles, and mixture of sand, clay, rock particles, and humushumus Most humus in in topsoilMost humus in in topsoil Good topsoil absorbs and retains moisture yet Good topsoil absorbs and retains moisture yet

allows excess water to drainallows excess water to drain It is rich in nutrients but low in saltsIt is rich in nutrients but low in salts

Such soil is produced by long-term interactions Such soil is produced by long-term interactions between the soil and plants growing in itbetween the soil and plants growing in it

MismanagementMismanagement

Plowing land removes the roots that hold the Plowing land removes the roots that hold the soil in placesoil in place This increases the rate of soil erosion-the wearing This increases the rate of soil erosion-the wearing

away of surface soil by water and windaway of surface soil by water and wind

In some parts of the world with dry climate, a In some parts of the world with dry climate, a combination of farming, overgrazing of animals, combination of farming, overgrazing of animals, and drought has turned once productive areas and drought has turned once productive areas into deserts (desertification)into deserts (desertification)

MismanagementMismanagement

Overgrazing: Overgrazing: When livestock overgraze, the grasses die and are When livestock overgraze, the grasses die and are

replaced by scrub, weeds, and toxic plants that do replaced by scrub, weeds, and toxic plants that do not provide good pasturenot provide good pasture

Death of grasses with wide-branching roots Death of grasses with wide-branching roots increases runoff of precipitation, causing soil erosionincreases runoff of precipitation, causing soil erosion

Ruins wildlife habitats-livestock trample the fertile Ruins wildlife habitats-livestock trample the fertile areas that border streams, killing plants, causing areas that border streams, killing plants, causing erosion of stream bankserosion of stream banks

Sustaining landSustaining land

Contour plowing: fields are plowed Contour plowing: fields are plowed across the slope of the land to reduce across the slope of the land to reduce erosionerosion

Leaving stems and roots of previous Leaving stems and roots of previous year’s crop in place to help hold the soil year’s crop in place to help hold the soil and planting the field with rye rather than and planting the field with rye rather than leaving it unprotected from erosionleaving it unprotected from erosion