1. Crops and Soil

2. Questions to Answer
How does traditional agriculture differ from modern agriculture?
What are the major layers of soil?
Where would you find the most amount of living organisms in soil?
What are pesticides and why are they used?
How are pesticides both beneficial and harmful?

3. Agriculture
The Earth has a limited area of arable land, land that can be used to grow crops.
Basic processes of farming include:
Plowing
Fertilization
Irrigation
Pest control

4. Traditional Agriculture
Plows are traditionally pushed by the farmer or pulled by livestock.
Helps crops grow by mixing soil nutrients, loosening soil particles, and uprooting weeds.
Organic fertilizers, such as manure, are used to enrich the soil.
Fields are irrigated by water flowing through ditches.
Weeds are removed by hands or machine.

5. Modern Agriculture
Machinery powered by fossil fuels is used to plow the soil and harvest crops.
Synthetic chemical fertilizers are used instead of manure.
Overhead sprinklers and drip systems are used for irrigation.

6. Soil
Why might we refer to fertile soil as the living Earth?

7. Mechanical Weathering
How Soil Forms
Chemical Weathering
Mechanical Weathering
Minerals in the rock chemically react with substances to form new materials.
**New substance
Rocks physically breaking apart.
**Same substance, different form

8. How Soil Forms
Temperature changes and moisture cause rock to crack and break apart.
It can take hundreds or even thousands of years for these geological processes to form a few centimeters of soil.

9. Topsoil The surface layer of soil Usually richer in organic matter
Fertile topsoil is composed of living organisms, rock particles, water, air, and organic matter, such as dead or decomposing organisms (humus).
Referred to as the A Horizon.

10. Subsoil
Larger rock particles with organic matter, and inorganic compounds.
Referred to as B Horizon.

11. Rock Particles Rock that has undergone weathering
Referred to as C Horizon.

12. Bedrock
Solid rock layer
Also referred to as Parent Material

13. Soil Erosion
Erosion is the wearing away of rock or soil by wind and water.
About half of the original topsoil in the U.S. has been lost to erosion in the past 200 years.
Almost all farming methods increase the rate of soil erosion.

14. Land Degradation
Land degradation happens when human activity or natural processes damage the land so that it can no longer support the local ecosystem.
Soil usually erodes downhill; soil conservation methods focus on preventing downhill erosion.
Contour plowing
No-till farming

15. Enriching Soil
Inorganic fertilizers (containing nitrogen, potassium, and phosphorous) have increased food production.
If erosion occurs in areas where the soil has been fertilized with inorganic chemicals, fertilizers and pesticides may pollute waterways.
Compost is used to enhance soil—using both organic and inorganic materials.

16. Pest Control
Pest- any organism that occurs where it is not wanted or that occurs in large enough numbers to cause economic damage.
Includes: insects, plants, fungi, microorganisms
Pesticides are chemicals used to kill insects, weeds, and other crop pests.
Can also harm beneficial plants, insects, wildlife, and even people.

17. Questions to Answer
How does traditional agriculture differ from modern agriculture?
What are the major layers of soil?
Where would you find the most amount of living organisms in soil?
What are pesticides and why are they used?
How are pesticides both beneficial and harmful?