Presentation is loading. Please wait.

Presentation is loading. Please wait.

Where does our food come from?

Similar presentations

Presentation on theme: "Where does our food come from?"— Presentation transcript:

1 Where does our food come from?
Croplands (mostly grain) – provide 77% of the world’s food Rangelands (meat) supply 16% Oceanic fisheries (fish and shellfish) – 7%

2 How Is Food Produced? Sources of food
Primary plants: Wheat, corn, and rice Primary animals: fish, beef, pork, and chicken 14 plant and 8 animal species provide 90% of the global food calories

3 Major Types of Agriculture
Industrialized agriculture Large amounts of fossil fuel, water, fertilizer, and pesticides to produce monoculture crops or livestock animals Plantation Form of industrialized agriculture – single ownership Traditional subsistence agriculture Produce only enough for the family Traditional intensive agriculture Increase outputs for profit

4 Industrialized Agricultural Wastes and Land Pollution
Animal Confinement Waste runoff Overgrazing Increases soil erosion Sedimentation Nutrient application Irrigation Pesticides

5 Waste runoff increases nutrients
and pathogens in streams

6 Overgrazing typically strips the land of any natural protection and leaves the soil very susceptible to erosion

7 Runoff carries sediments, nutrients and
pesticides into streams that damages fish habitat

8 Agriculture alters native habitats
and reduces native biodiversity

9 Major Types of Agriculture
Plantation - Form of agriculture that involves concentrated ownership of land with the means of production in the hands of one family or corporation, the use of hired labor, and mono-crop production for sale. Cash crops mostly for sale in developed countries Bananas, coffee, soybeans

10 Traditional Plantation Industrialized

11 World Food Production Industrialized Traditional

12 Producing Food by Green-Revolution Techniques
Since 1950, increase in global food production has come from increased yields per unit area of crop land.

13 Producing Food by Green-Revolution Techniques
Green revolution involves three steps: High-input monoculture using selectively bred or genetically-engineered crops High yields using high inputs of fertilizer, extensive use of pesticides and high inputs of water Multiple cropping – increase the number of crops grown per year on a plot of land.

14 Green Revolutions First green revolution (developed countries)
Second green revolution (developing countries) Major International agricultural research centers and seed banks

15 Producing Food by Traditional Techniques
Interplanting – simultaneously grow several crops on the same ground. Reduces chance of losing year’s crop to pests, bad weather, etc.

16 Producing Food by Traditional Techniques
Types of Interplanting Polyvarietal cultivation – planting several varieties of the same crop Intercropping – grow two or more different crops at the same time (grain+nitrogen fixing plant) Agroforestry (alley cropping) – crops and trees are grown together Polyculture – many different types of plants that mature at different times are grown together

17 Causes of Soil Erosion Wind Water
People – farming, logging, construction (or any activities that weaken root strength)


19 Soil erosion in a wheat field

20 Areas of serious concern Stable or nonvegetative areas
Global Soil Erosion Areas of serious concern Areas of some concern Stable or nonvegetative areas

21 Soil Degradation on Irrigated Land
Salinization Waterlogging Evaporation Transpiration Waterlogging Less permeable clay layer

22 Reducing and Cleaning Up Salinization
Reduce irrigation Switch to salt-tolerant crops Flush soils Not growing crops for 2-5 years Install underground drainage

23 Saltwater and drainage is a continual problem for lowland agriculture near Puget Sound.

24 Tidegate – lets water out, but not back in.

25 Solutions: Soil Conservation


27 Soil Restoration Organic fertilizer Animal manure
Green manure – fresh cut vegetation Compost Crop rotation – legume crops add nitrogen to soil Commercial inorganic fertilizer

28 Catching and Raising More Fish
Fisheries Fishing methods Overfishing Commercial extinction Aquiculture Fish farming and ranching

29 And our commercial fleets

30 Pesticides: Types Chemicals that kill undesirable organisms
Insecticides - insects Herbicides - plants Fungicides - fungus Rodenticides - rodents

31 First Generation Pesticides
Primarily natural substances Sulfur, lead, arsenic, mercury Plant extracts: nicotine, pyrethrum

32 Second Generation Pesticides
Primarily synthetic organic compounds Broad-spectrum agents – toxic to many species Narrow-spectrum agents – toxic to few species Persistence in the environment

33 The Case for Pesticides
Save human lives – spread of disease Increase food supplies and lower costs Work better and faster than alternatives Health risks may be insignificant compared to benefits Newer pesticides are becoming safer New pesticides are used at lower rates

34 Characteristics of an Ideal Pesticide
Affects only target pests Harms no other species No genetic resistance Breaks down quickly in the environment Be more cost-effective than doing nothing

35 The Case Against Pesticides
Genetic resistance The pesticide treadmill – pay more for less effect Can kill non-target and natural control species Can cause an increase in other pest species Pesticides do not stay put Can harm wildlife Potential human health threats

36 Bioaccumulation and Biomagnification
Persistent (non-biodegradable) toxins build up in an animal over time = bioaccumulation Become more concentrated at higher trophic levels = biomagnification

37 Integrated Pest Management
Ecological system approach Reduce pest populations to economic threshold Field monitoring of pest populations Use of biological agents – natural predators, parasites, disease Chemical pesticides are last resort

38 Why is Integrated Pest Management not More Widely Used?
Requires expert knowledge Slower than conventional pesticides Initial costs may be high Hindered by pesticide industry

39 Solutions: Sustainable Agriculture
Low-input agriculture Organic farming Profitable Increasing funding for research in sustainable techniques



Download ppt "Where does our food come from?"

Similar presentations

Ads by Google