Land Management
Competing uses for land: Forests (30% and decreasing) Agriculture (40% and increasing) Urbanization (5% and increasing)
Forest Uses Wood to build structures Wood for heat energy
Agriculture Uses Definition - the growing of crops & the tending of livestock for subsistence, sale, or exchange
Three Main Types of Agriculture 1. Subsistence Industrialized 3. Sustainable
Subsistence Agriculture Grow food to feed own family: Human Labor Slash and Burn Field Rest Periods Variety of Crops Fertilizer - Animal Manure No Pesticides
Industrialized Agriculture One type of crop or animal raised for large consumption uses large amounts of : a) fossil fuel energy b) water
Industrialized Agriculture Mechanization Monocropping Synthetic Pesticides Synthetic Fertilizers Genetic Engineering Irrigation
Mechanization – Large Machinery causes land degradation through soil compaction exacerbates soil erosion causes decline in soil fertility erosion damage causes decreased water quality
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
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
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
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
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
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.
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
Sustainable Agriculture (Organic) Crops grown in harmony with the environment Health of humans and livestock important Environment important Workers important e.g. Organic agriculture
Sustainable Agriculture Cont’d Includes the use of: -Soil conservation Use of alternatives to pesticides Organic Fertilizers
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
Soil Conservation Methods cont’d Major Methods Include: Conservation tillage Contour farming, Terracing, Strip cropping, & Alley cropping Windbreaks
Soil Conservation Methods cont’d Conservation Tillage - crop cultivation with little or no soil disturbance ▪ Minimum Tillage ▪ No-till Farming
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
Soil Conservation Methods cont’d ▪ Terracing - used on steeper slopes
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.
Soil Conservation Methods cont’d 3. Windbreaks ▪ Windbreaks (Shelterbelts) - row of trees planted to block wind flow
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
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.
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
Alternatives to Pesticides cont’d 7. Zapping Foods With Radiation - gamma irradiation of foods is used to kill insects & prevent them from reproducing
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
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
Organic Fertilizer cont’d Compost - partially decomposed organic plant and animal matter - made up of animal manure, topsoil, kitchen scraps - rich, natural fertilizer
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?