1. Agriculture and Soil

2. Green Revolution
The Green Revolution was a shift in farming methods from physical labor to mechanized large industrial operations during the 20th century.
This also included
Fertilization
irrigation
improved crop varieties.
These changes increased food production and more people were fed. (yay! Right?)

3. Impacts of the Green Revolution
Modern agriculture has a greater harmful environmental impact than any human activity.
Loss of a variety of genetically different crop and livestock strains might limit raw material needed for future green and gene revolutions.
In the U.S., 97% of the food plant varieties available in the 1940 no longer exist in large quantities.
Crazy decline in domestic biodiversity!

4. Industrial Food Production aka: High Input Agriculture
About 80% of the world’s food supply is produced by industrialized agriculture.
Uses large amounts (high inputs) of
fossil fuel
Energy
Water
Commercial fertilizers
Pesticides
Monocultures (growing only one crop)

5. Advantages of Intensive Agriculture
Maximum yield from minimum land use
World grain production has almost tripled in the last 50 years.
Higher yield per season
Mechanization is efficient and reduces labor costs.
Per capita food production has increased, reducing global hunger.
The cost of food has declined, and more food is now traded globally.
Seeding (top) and planting (below): two practices once exclusively done by hand

6. Disadvantages of Intensive Agriculture
Increases in yields may not be sustainable
Pests and diseases spread rapidly in monocultures.
Pesticide use is escalating yet its effectiveness is decreasing.
Pesticides and fertilizers are energy expensive.
Fertilizer use is increasing but soil and water quality continue to decline.
Poor countries are reliant financially on outside assistance.
Heavy machinery is expensive to purchase, operate, and maintain.
Intensive agriculture uses high inputs of energy to achieve high yields

7. Major Environmental Effects of Food Production: Water
Aquifer depletion
Increased runoff and flooding from land cleared to grow crops
Fish kills from pesticide runoff
Surface and groundwater pollution from pesticides and fertilizers
Over fertilization of lakes leads to eutrophication
You need to be able to clearly explain these examples…

8. Major Environmental Effects of Food Production: Soil
Erosion
Loss of soil fertility (leads to less nutrients in food)
Salinization
Water-logging
Desertification
Pollution by pesticides
You need to be able to clearly explain these examples…

9. Major Environmental Effects of Food Production: Air
Greenhouse gas emissions from fossil fuels
Other air pollutants and particulates from fossil fuels
Pollution from pesticide sprays
You need to be able to clearly explain these examples…

10. Major Environmental Effects of Food Production: Human Health
E. Coli contamination of meat & produce
Pesticide residues in drinking water, food, and air
Contamination of drinking and swimming water with disease organisms from livestock wastes
You need to be able to explain these…
“food production decreases biodiversity”
Example: pesticide residue, explanation: to reduce pests and increase food production, effect: people working in McFarland CA have cancer and asthma

11. Major Environmental Effects of Food Production: Biodiversity
Loss and degradation of habitat from clearing grasslands and forests and draining wetlands
Fish kills from pesticide runoff
Killing of wild predators to protect live stock
Loss of genetic diversity from replacing thousands of wild crop strains with a few monoculture strains
You need to be able to explain these…
“food production decreases biodiversity”
Example: pesticide residue, explanation: to reduce pests and increase food production, effect: people working in McFarland CA have cancer and asthma

12. Traditional Agriculture: Low Input Polyculture
Research has shown that, on average, low input polyculture (more than one crop planted together) produces higher yields than high-input monoculture.
However it takes time and planning

13. Traditional Agriculture: Low Input Polyculture
Many farmers in developing countries use low-input agriculture to grow a variety of crops on each plot of land through:
Intercropping: two or more different crops grown at the same time (basically in rows next to eachother).
Agroforestry: crops and trees are grown together.
Polyculture: different plants are planted together. (beans with corn – beans climb up corn – everyone wins)

14. Subsistence Agriculture
Self-sufficiency farming in which the farmers focus on growing enough food to feed themselves and their families.
Typically uses traditional low input agricultural methods
Examples:
Shifting cultivation
Slash and burn agriculture
Nomadic herding
Intercropping

15. Sustainable Agriculture
Industrial agriculture may seem necessary, but less-intensive agricultural methods may be better in the long run
Sustainable agriculture = does not deplete soil, pollute water, or decrease genetic diversity
Low-input agriculture = uses smaller amounts of pesticide, fertilizers, growth hormones, water, and fossil fuel energy than industrial agriculture
Organic agriculture = Uses no synthetic fertilizers, insecticides, fungicides, or herbicides
Relies on biological approaches (composting and biocontrol)

16. A standardized meaning for “organic”
People debate the meaning of the word “organic”
Organic Food Production Act (1990) establishes national standards for organic products
The USDA issued criteria in 2000 by which food could be labeled organic
Some states pass even stricter guidelines for labeling

17. The market for organic food is increasing
Sales increased 20% per year in Canada and the U.S. from
Expanded by a factor of 40 in Europe
Amount of land for organic farming is increasing
10-35% per year in the U.S. and Canada
In 2005 the U.S. had 1.7 million acres of organic cropland and 2.3 million acres of organic pastureland

18. The benefits of organic farming
For farmers:
Lower input costs, enhanced income from higher-value products, reduced chemical costs and pollution
Obstacles include the risks and costs of switching to new farming methods and less market infrastructure
For consumers:
Concern about pesticide’s health risks
A desire to improve environmental quality
Obstacles include the added expense and less aesthetically appealing appearance of the product

19. The U.S. doesn’t financially support organic farmers
In 1993, the European Union adopted a policy to support farmers financially during conversion to organic farming
The U.S. offers no such support
Organic production lags in the U.S.
Farmers can’t switch, because they can’t afford the temporary loss of income
In the long run, organic farming is more profitable

20. Locally supported agriculture is growing
In developed nations, farmers and consumers are supporting local small-scale agriculture
Fresh, local produce in season
Community-supported agriculture = consumers pay farmers in advance for a share of their yield
Consumers get fresh food
Farmers get a guaranteed income
Farmers Markets—growing and becoming more popular locally.

21. Soil
Uppermost layer of earth’s crust that supports plants, animals and microbes
Soil Forming Factors
Parent Material
Time
Climate
Vegetation & Organisms
Topography

22. Soil Problems Soil Erosion
Wearing away or removal of soil from the land
Caused primarily by water and wind
Why a problem?
Causes a loss in soil fertility as organic material and nutrients are eroded
More fertilizers must be used to replace nutrients lost to erosion
Accelerated by poor soil management practices

23. Salinization & Waterlogging

24. Soil Salinization
Gradual accumulation of salt in the soil, usually due to improper irrigation techniques
Often in arid and semi-arid areas
The little precipitation that falls is quickly evaporated
Leaves behind salts
Salt concentrations get to levels toxic to plants

25. Desertification
Degradation of once-fertile rangeland, agricultural land, or tropical dry forest into nonproductive desert
Typically a human-induced condition
Change in vegetation changes climate, further decreasing precipitation levels (usually in a positive feedback loop scenario)
Asia and Africa – largest areas – many droughts

26. Soil Conservation Policies in US
Soil Conservation Act 1935
Authorized formation of Soil Conservation Service, now called Natural Resource Conservation Service (NRCS)
Assess soil damage and develop policies to improve soil
Food Security Act (Farm Bill) 1985
Required farmers with highly erodible soil had to change their farming practices
Instituted Conservation Reserve Program (CRP)
Pays farmers to stop farming highly erodible land

27. Soil Conservation Practices
Conservation Tillage
Residues from previous year’s crops are left in place to prevent soil erosion
Includes no till agriculture

28. Soil Conservation Practices
Crop Rotation
Planting a series of different crops in the same field over a period of years
Lessens pest and insect disease
Lets nutrients specific for certain plants naturally replenish

29. Soil Conservation Practices
Contour Plowing
Plowing around hill (following natural contour of land) instead of up-down
Decreases soil erosion

30. Soil Conservation Practices
Strip Cropping
Alternating strips of different crops along natural contours

31. Soil Conservation Practices
Terracing
Creating terraces on steep slopes to prevent erosion

32. Soil Conservation Practices
Agroforestry
Trees and crops are planted together to improve soil fertility in degraded soils
Trees grow much longer and provide many soil benefits:
- reduces soil erosion
- regulates water
- provides habitat for natural enemies of crop pests
- leaf litter regenerates soil
- shade
Example: Acacia trees and millet

33. Soil Reclamation Two steps Stabilize land to prevent further erosion
Restoring soil to former fertility
Best way to do this is to plant shelterbelts
Row of trees planted to reduce wind erosion of soil