Lesson 8

Soil Use, Abuse, and Conservation

Think About It…

Why is soil important?

Focus Question…

Why is it important to preserve and conserve our soil?

Natural Resources: An Overview…

1. What are renewable resources?• those possible to use indefinitely without causing a reduction

in supply• Examples include fresh air, fresh surface water, most

groundwater, fertile soil, elements that cycle through Earth, all living things

Natural Resources: An Overview…

2. What is a nonrenewable resource?

• exist in a fixed amount and can only be replaced by processes that take thousands of years.

• Examples include fossil fuels, gemstones, and elements such as gold, copper, and silver.

http://library.thinkquest.org/17531/fossil.html

Old Growth Trees (Mt. Ranier, Washington) – Nonrenewable!

Mariposa Grove of Giant Sequoias, Yosemite, CA

Muir Woods NM, CA

Muir Woods NM, CA

Conventional Farming…

3. What is conventional agriculture?

• Standard farming techniques - makes farming easier & grows more food.

• Includes:– plowing & tilling– pesticides – factory-made

fertilizers– monoculture

http://www.southernstates.com/catalog

http://permaculturenews.org/2011/01/26/why-pasture-cropping-is-such-a-big-deal/

http://eartheasy.com/grow_nat_pest_cntrl.htm

Sustainable Farming…4. What is sustainable

agriculture?• Techniques - conserve

soil, recycle nutrients, & protect health

• Includes: no till farming, natural pest control, & natural fertilizers

Also called organic farming.

Manure-spreading Truck

http://www.usawaterquality.org/themes/npm/research/P_Organic.html

Beneficial Insect Predator

Soil, Agriculture, and Environmental Issues…

How long can it take to form just a few inches of soil?

• 1000 years!

Each decade, Earth loses about 7 % of our topsoil.

This field in England was left bare and is prone to erosion.

http://indianapublicmedia.org/amomentofscience/disappearing-soil/

Desertification…

1. Definition - productive land becomes a desert b/c of overgrazing or removing vegetation in dry areas

Impact - It turns usable land into a desert

2. Prevention…

a. graze cattle wisely

b. plant vegetation to retain water• See next slide

Desertification in the Sahel…

http://oceanworld.tamu.edu/resources/environment-book/Images/water-hole-cattle.jpg

Monoculture and Biodiversity Loss…

1. Biodiversity is… the number & variety of living things.

Ecosystems with a high biodiversity (like rain forests) are healthier & more stable than those with fewer species.

http://www.srl.caltech.edu/personnel/krubal/rainforest/Edit560s6/www/animals.html

Monoculture…

2. Definition: planting of just one species in a field

Used b/c it is easier for farmers

3. Impact: It decreases biodiversity & makes crops more susceptible to disease

Sustainable alternative plant several species

http://www.bio.davidson.edu/people/kabernd/seminar/2004/Grp4/monoculture.html

A Monoculture Field

Pesticides

1. Definition: chemicals used to kill pests that eat crops.

Used to save crops!

2. Impacts: – kill good insects &

decomposers (such as worms).

– pollute water & soil – build up in the food

chain

Moses Cone Manor, NC

Pesticides containing lead and arsenic were used in the apple orchards. The soil

is still contaminated!

Pesticides…

Sustainable alternative using carnivorous insects to eat the pests

(Like praying mantis and ladybugs)

Topsoil Loss: Erosion by Plowing

1. Topsoil is hard to replace b/c… it takes thousands of years to form

2. Plowing causes erosion b/c it clears native vegetation or forests & exposes topsoil

Used b/c it is an easy way to clear land3. Impact: causes a loss of topsoil

Things in original soil that can’t be replaced are trace minerals, earthworms, N-fixing bacteria,

and humus.

Notice the soil loss behind the plow…

And this plow in the San Joaquin Valley, CA…

Soil Conservation

To Reduce soil erosion…• No-till farming• Terracing• Contour farming • Windbreaks• Gully reclamation

See next few slides.

Topsoil Loss: Erosion by Plowing

3a. Sustainable alternatives that help conserve topsoil: no-till farming (conservation tillage)

Topsoil Loss: Erosion by Plowing

3b. Sustainable alternatives that help conserve topsoil: clover cover

http://www.extension.org/pages/31597/overview-of-vineyard-floor-management

Reduce Soil Erosion : Terracing (Add to notes.)

http://www.acca21.org.cn/image/p3-12.gif

Reduce Soil Erosion : Contour farming

http://www.ga.nrcs.usda.gov/programs/images/grassedwaterways.jpg

Reduce Soil Erosion : Windbreaks

http://www.weru.ksu.edu/pics/control/1059.jpg

Reduce Soil Erosion : Gully reclamation

http://www.dpi.vic.gov.au/dpi/vro/vroimages.nsf/Images/parwan_vall_gully_head/$File/parwan_valley.jpg

Deforestation…1. Definition: removal of trees without

replanting

2. Impacts: loss of soil and clogs waterways with sediment (sedimentation)

Sustainable Alternatives:

a. selective logging

b. buffer zones of trees along streambeds.

Deforestation: Selective Logging…

The impact of selective logging (taking only some trees from a forest) can be seen in this view of the Tīhoi state forest in 1976.

Above the logging road 55% of the timber has been removed, below it only 30% has been removed, while further down is an area of unlogged native forest.

Between 1975 and 1984, when selective logging was the only type of harvesting permitted in native forests, the Forest Service carried out trials to see if the damage it caused could be reduced.

http://www.teara.govt.nz/en/forestry-research/2/2

Urbanization…1. Definition: People move to cities for jobs and

services.

2. Impacts:

Natural habitats are lost when forests are cleared & wetlands are filled.

a. Construction causes the erosion of topsoil.

b. Development takes land away from agricultural use

c. Large volumes of solid waste are produced.

See next slide…

Urbanization – An Extreme Example…Lagos, Nigeria

http://mycontinent.co/IMGNigeria/Cities/lagos_traffic.jpg

Urbanization…

Sustainable Alternates:

- Leave some vegetation

- Planting greenways

- Urban gardens

http://morgreen.org/urban-gardens/

Properly Designed Landfill…

http://your.kingcounty.gov/dnr/kidsweb/images/landfill_diagram.gif