1. Land Management

2. Competing uses for land:
Forests (30% and decreasing)
Agriculture (40% and increasing)
Urbanization (5% and increasing)

3. Forest Uses
Wood to build structures
Wood for heat energy

4. Agriculture Uses
Definition - the growing of crops & the tending of livestock for subsistence, sale, or exchange

5. Three Main Types of Agriculture
1. Subsistence
Industrialized
3. Sustainable

6. Subsistence Agriculture
Grow food to feed own family:
Human Labor
Slash and Burn
Field Rest Periods
Variety of Crops
Fertilizer - Animal Manure
No Pesticides
                                                        

7. Industrialized Agriculture
One type of crop or animal raised for large consumption
uses large amounts of :
a) fossil fuel energy
b) water

8. Industrialized Agriculture
Mechanization
Monocropping
Synthetic Pesticides
Synthetic Fertilizers
Genetic Engineering
Irrigation

9. Mechanization – Large Machinery
causes land degradation through soil compaction
exacerbates
soil erosion
causes decline in
soil fertility
erosion damage causes decreased water quality

10. Monocropping:
- also called monoculture
cultivation of a single crop, usually on a large area of land
simplifies ecosystems, reducing biodiversity
encourages the build up of pests thus increasing the use of pesticides
depletes the soil of nutrients

11. Use of Pesticides Pesticide
- any chemical designed to kill or inhibit the growth of an organism that people consider undesirable
- fast-breeding insect species undergo natural selection and develop genetic resistance to chemical pesticides
                                                                
                                             
                                

12. Effects of Pesticide Use
- harmful to the environment
Pesticides linked to cancers and low sperm count
persistent pesticides adhere to sediment and become bioaccumulated and biomagnified
                                                                
                                             
                                

13. Use of Fertilizers Fertilizers
- Substances that add plant nutrients to soil and improves its ability to grow crops
- Leads to eutrophication
2 Main Types of Fertilizers:
- Organic Fertilizer
- Commercial Inorganic Fertilizer

14. Genetic Engineering
Crops that have been genetically modified to add a specific trait.
For Example
A gene from a bacteria was inserted into corn DNA to make it resistant to a specific pest.
A gene for drought tolerance was taken from one plant and inserted into another plant that did not grow well in drought conditions.
Corn and soybean crops have been genetically modified to be resistant to the herbicide Roundup
Long term effects are not known

15. Irrigation The application of water to crops Types
Natural/Rainfall
Flood irrigation
Overhead/sprinkler
Drip irrigation (most efficient - 90%)
-Flood irrigation is wasteful and causes salinization.

16. Salinization Due to Irrigation
- accumulation of salts in soil that can eventually make the soil unable to support plant growth
- lowers crop growth and yields
- kills crop plants & ruins the land

17. Sustainable Agriculture (Organic)
Crops grown in harmony with the environment
Health of humans and livestock important
Environment important
Workers important
e.g. Organic agriculture

18. Sustainable Agriculture Cont’d
Includes the use of:
-Soil conservation
Use of alternatives to pesticides
Organic Fertilizers

19. Soil Conservation Methods
- methods used to:
◦ reduce soil erosion
◦ prevent depletion of soil nutrients
◦ restore nutrients
- most methods involve keeping the soil covered with vegetation

20. Soil Conservation Methods cont’d
Major Methods Include:
Conservation tillage
Contour farming, Terracing, Strip cropping, & Alley cropping
Windbreaks

21. Soil Conservation Methods cont’d
Conservation Tillage
- crop cultivation with little or no soil disturbance
▪ Minimum Tillage
▪ No-till Farming

22. Soil Conservation Methods cont’d
2. Contour Farming, Terracing, Strip Cropping & Alley Cropping
- used mainly on sloping land which is more prone to erosion
▪ Contour Farming
- used on gently sloping land

23. Soil Conservation Methods cont’d
▪ Terracing
- used on steeper slopes

24. Soil Conservation Methods cont’d
▪ Alley Cropping (Agroforestry)
- planting crops with rows of trees on each side. Helps erosion while growing trees at the same time.

25. Soil Conservation Methods cont’d
3. Windbreaks
▪ Windbreaks (Shelterbelts)
- row of trees planted to block wind flow

26. Alternatives to Pesticides
Cultivation Practices
- mow weeds
- rotate crops
- plant rows of hedges or trees
Resistant Crop Varieties
- genetically resistant to certain pest insects, fungi and diseases
                                                                                          

27. Alternatives to Pesticides cont’d
3. Natural Enemies (Biological Control)
- predators, parasites & bacteria can be encouraged or imported to regulate pest populations
4. Birth Control (Reproductive Controls)
- males are lab-raised and sterilized, then released into population.

28. Alternatives to Pesticides cont’d
Insect Sex Attractants (Pheromones)
- when a female is ready to mate she releases a pheromone (chemical sex attractant). Males come and are trapped.
6. Insect Hormones
- hormones: chemicals produced by an organism to control its growth & development

29. Alternatives to Pesticides cont’d
7. Zapping Foods With Radiation
- gamma irradiation of foods is used to kill insects & prevent them from reproducing

30. Organic Fertilizer Organic Fertilizer
- organic materials, such as animal manure, applied as a source of plant nutrients
3 Basic Types of Organic Fertilizer
- Animal Manure
- Green Manure
- Compost

31. Organic Fertilizer cont’d
Animal Manure
- dung and urine of farm animals
- improves soil structure
- stimulates beneficial bacteria and fungi
Green Manure
- freshly-cut or still-growing vegetation that is ploughed into the soil

32. Organic Fertilizer cont’d
Compost
- partially decomposed organic plant and animal matter
- made up of animal manure, topsoil, kitchen scraps
- rich, natural fertilizer

33. Review What is most of our land used for?
Our forests are used for what two purposes?
What is another term for sustainable agriculture?
If you lived on steep slopes what type of contour farming would work the best to prevent erosion?
What is it called when the DNA of plants has been altered to change a trait of that plant?