1. Environmental Science
Chapter 9
Notes #2

2. Agriculture and Soil Arable Land –
Fertile land that can grow crops well
Amount decreases every year
Population growth, erosion, poor farming methods
World wide 1/5th was lost in just 15 years
1985 To 2000
In comparison to 10,000 years of farming
Houses, roads, mines, farms left bare

3. Agriculture and Soil Ancient Methods of Farming Plowing Fertilization
People/animals, cutting through/turning over)
Fertilization
manure
Irrigation
Digging ditches for water to flow through
Pest control
Pulling weeds, covering plants, etc)
Technology has made it easier, increases erosion
Machinery
Synthetic fertilizers
Sprinklers, advanced water systems
Chemicals that kill pests

4. Agriculture and Soil Fertile Soil
Supports rapid growth of healthy plants
Plants grow in topsoil
Loose surface layer
Fertile- consists of rock, water, air, organic matter
Living Things
Fungi/bacteria/microorganisms – decompose
Bacteria “fix” nitrogen
Worms/insects/break up soil, letting in air (aeration) & water
Bottom = bedrock

5. Agriculture and Soil Takes 1000’s of years to form a few cm of soil
Bedrock breaks up due to temp changes and moisture (causing breaking/cracking)
Mixes with organic decaying matter, water and air
Voila! Soil has formed!

6. Agriculture and Soil Topsoil erosion
Wearing away of topsoil by wind and water
In US 50% of topsoil has been lost in the last 200 years
One of top ecological problems we face today
Plowing and harvesting contribute to erosion
Produces loose surface area that can blow/wash away
Removes roots that hold soil in place
Clearing of trees increases amt of water flowing over the ground
Trees absorb tons of water

7. Agriculture and Soil Desertification
Loss of topsoil that destroys fertility
Result of too many crops grown in the land (no fallow time)
Overgrazing (no fallow time)
Especially severe in dry areas – no water holding soil together
Results in erosion

8. Agriculture and Soil Soil Conservation 1. Contour plowing
Strips of vegetation in between plowed areas
2. No Till Farming
Slits to plant new crop among the remains of the old crop
3. Organic v. Inorganic Fertilizer
Organic helps replenish the soil

9. Agriculture and Soil Sustainable agriculture Low in Put Farming
Without lots of energy or pesticides & fertilizers
Example:
Organic Farming
No synthetics

10. Agriculture and Soil Salinization Accumulation of salts in soil
Caused by irrigation
Ground Water has more salt than rainwater
Most irrigation comes from ground and rivers
When it evaporates, leaves behind salt, kills seedlings
Irrigation also causes groundwater levels to rise, resulting in the same effect

11. Agriculture and Soil Old and New Foods
Researchers are looking at ancient and new plants for 2 purposes
To find foods that grow easily and have a high percent yield
Plants that improve soil conditions so the area can again be used for agricultural purposes

12. Agriculture and Soil Old and New Foods – Aquaculture “Fish Farming”
Many ponds, raising fish of different ages, to be harvested
Water circulates through bring in oxygen and removing waste
Fish Ranch
Example- salmon, raised and released
No fishing zones to reduce over harvesting
23% of seafood comes from aquaculture
Drawbacks
Uses local water supply/wetlands are sometimes damaged