1. Pests, Soil and Agriculture
Focus on Pests and Management Techniques
Wrap up with Sustainable Farming Techniques
Focus on Soil – What it is, its importance, and its health.

2. Many environmental problems result from agriculture:
Desertification
Degradation of water aquifers
Salinization
Accumulation of toxic metals and organic compounds
Loss of biodiversity
Soil erosion
Sediment transport and deposition downstream
On-site pollution from fertilizers and pesticides
Deforestation

3. PROTECTING FOOD RESOURCES: PEST MANAGEMENT
Organisms found in nature (such as spiders) control populations of most pest species as part of the earth’s free ecological services.
Figure 13-27

4. PROTECTING FOOD RESOURCES: PEST MANAGEMENT
We use chemicals to repel or kill pest organisms as plants have done for millions of years.
Chemists have developed hundreds of chemicals (pesticides) that can kill or repel pests.
Pesticides vary in their persistence.
Each year > 250,000 people in the U.S. become ill from household pesticides.

5. PROTECTING FOOD RESOURCES: PEST MANAGEMENT
Advantages and disadvantages of conventional chemical pesticides.
Figure 13-28

6. Individuals Matter: Rachel Carson
Wrote Silent Spring which introduced the U.S. to the dangers of the pesticide DDT and related compounds to the environment.
Figure 13-A

7. The ideal Pesticide and the Nightmare Insect Pest
The ideal pest-killing chemical has these qualities:
Kill only target pest.
Not cause genetic resistance in the target organism.
Disappear or break down into harmless chemicals after doing its job.
Be more cost-effective than doing nothing.

8. Superpests Superpests are resistant to pesticides.
Superpests like the silver whitefly (left) challenge farmers as they cause > $200 million per year in U.S. crop losses.
Figure 13-29

9. Pesticide Protection Laws in the U.S.
Government regulation has banned a number of harmful pesticides but some scientists call for strengthening pesticide laws.
The Environmental Protection Agency (EPA), the Department of Agriculture (USDA), and the Food and Drug Administration (FDA) regulate the sales of pesticides under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA).
The EPA has only evaluated the health effects of 10% of the active ingredients of all pesticides.

10. Other Ways to Control Pests
Genetic engineering can be used to develop pest and disease resistant crop strains.
Both tomato plants were exposed to destructive caterpillars. The genetically altered plant (right) shows little damage.
Figure 13-32

11. Case Study Integrated Pest Management: A Component of Sustainable Agriculture
An ecological approach to pest control uses a mix of cultivation and biological methods, and small amounts of selected chemical pesticides as a last resort.
Integrated Pest Management (IPM)

12. Case Study Integrated Pest Management: A Component of Sustainable Agriculture
Many scientists urge the USDA to use three strategies to promote IPM in the U.S.:
Add a 2% sales tax on pesticides.
Establish federally supported IPM demonstration project for farmers.
Train USDA personnel and county farm agents in IPM.
The pesticide industry opposes such measures.

13. Biological Pest Control

14. Integrated Pest Management
Control of agricultural pests using several methods together, including biological and chemical agents
Goals:
To minimize the use of artificial chemicals
To prevent or slow the buildup of resistance by pests to chemical pesticides

16. Reducing Exposure to Pesticides
What Can You Do?
Reducing Exposure to Pesticides
• Grow some of your food using organic methods.
• Buy organic food.
• Wash and scrub all fresh fruits, vegetables, and wild foods you pick.
Figure 13.30
Individuals matter: ways to reduce your exposure to pesticides. QUESTION: Which two of these actions do you think are the most important?
• Eat less or no meat.
• Trim the fat from meat.
Fig , p. 299

17. Soil
Soil Formation: Soil is formed slowly as rock (the parent material) erodes into tiny pieces near the Earth's surface. Organic matter decays and mixes with inorganic material (rock particles, minerals and water) to form soil.
Soil Horizons (layers): Soil is made up of distinct horizontal layers; these layers are called horizons. They range from rich, organic upper layers (humus and topsoil) to underlying rocky layers ( subsoil, regolith and bedrock).

18. Humus
The main contributor to the fertility of the soil. It originates from decomposing material.
Found on the SURFACE of the soil
So for examples one reason why grasslands are considered the “bread baskets of the world is because of their great fertility due in large part to the natural humus which accumulates because grasses form a large amount of organic matter that decomposes.
Tropical rainforests, however, DO NOT have a large amount of humus because the decomposition rate there is so fast the nutrients are almost immediately reabsorbed by plants. This is why the tropical rainforest does not yield fertile soil when it is cut down.
Some forests do have humus, however, deciduous forests accumulate humus because of the decomposition of plants and animals. Temperate rainforests also contain humus because needles and leaves will decompose.
Importance: nutrients (fertility), holds water, improves soil aeration, prevents erosion, improves habitats for soil living organisms, improves soil structure, allows roots to grow more easily.

19. O Horizon - The top, organic layer of soil, made up mostly of leaf litter and humus (decomposed organic matter). A Horizon - The layer called topsoil; it is found below the O horizon and above the E horizon. Seeds germinate and plant roots grow in this dark-colored layer. It is made up of humus (decomposed organic matter) mixed with mineral particles. E Horizon - This eluviation (leaching) layer is light in color; this layer is beneath the A Horizon and above the B Horizon. It is made up mostly of sand and silt, having lost most of its minerals and clay as water drips through the soil (in the process of eluviation). B Horizon - Also called the subsoil - this layer is beneath the E Horizon and above the C Horizon. It contains clay and mineral deposits (like iron, aluminum oxides, and calcium carbonate) that it receives from layers above it when mineralized water drips from the soil above. C Horizon - Also called regolith: the layer beneath the B Horizon and above the R Horizon. It consists of slightly broken-up bedrock. Plant roots do not penetrate into this layer; very little organic material is found in this layer. R Horizon - The unweathered rock (bedrock) layer that is beneath all the other layers.

20. Testing Soil Chemical Physical pH salinity
organic content (measuring humus)
Testing for major elements such as N, P, K, S or trace elements such as Co, B, Ca, Mg etc.
Physical
Soil Texture
Porosity – how much water the soul can old due to the amount of air/space available
Moisture content

21. Global Outlook: Soil Erosion
Soil is eroding faster than it is forming on more than one-third of the world’s cropland.
Figure 13-10

22. Where Eroded Soil Goes: Sediments Also Cause Environmental Problems
Ways to slow erosion:
Making Soil Sustainable
Contour Plowing
No-Till Agriculture
Combination of farming practices that include not plowing the land and using herbicides to keep down weeds.

23. Desertification of arid and semi-arid lands
Figure 13.11
Natural capital degradation: desertification of arid and semiarid lands is caused by a combination of prolonged drought and human activities that expose soil to erosion. QUESTION: What three things would you do to reduce desertification? (Data from UN Environment Programme and Harold E. Drengue)
Moderate
Severe
Very severe

25. Case Study: Soil Erosion in the U.S. Some Hopeful Signs
Soil erodes faster than it forms on most U.S. cropland, but since 1985, has been cut by about 40%.
1985 Food Security Act (Farm Act): farmers receive a subsidy for taking highly erodible land out of production and replanting it with soil saving plants for years.

26. Desertification
Desertification is the deterioration of land in arid, semi- arid and dry sub humid areas due to changes in climate and human activities
Can be caused by
Poor farming practices
Conversion of marginal grazing lands to croplands

27. Desertification: Degrading Drylands
About one-third of the world’s land has lost some of its productivity because of drought and human activities that reduce or degrade topsoil.
Figure 13-12

28. Carrying Capacity of US Pasture & Rangelands
Bad farming practices have lead to an increase in desertification in the US.
Climate suggests that 1/3 of the earth should be deserts, however now deserts cover nearly 50% of the planet because of human action!
Average number of cows per square kilometer

29. Salinization and Waterlogging
Repeated irrigation can reduce crop yields by causing salt buildup in the soil and waterlogging of crop plants.
Figure 13-13

30. Solutions Soil Salinization Prevention Cleanup Reduce irrigation
Flush soil (expensive and wastes water)
Stop growing crops for 2–5 years
Figure 13.15
Solutions: methods for preventing and cleaning up soil salinization. QUESTION: Which two of these solutions do you think are the most important?
Switch to salt-tolerant crops (such as barley, cotton, sugarbeet)
Install underground drainage systems (expensive)
Fig , p. 281

31. Salinization and Waterlogging of Soils: A Downside of Irrigation
Example of high evaporation, poor drainage, and severe salinization.
White alkaline salts have displaced cops.
Figure 13-14

32. SUSTAINABLE AGRICULTURE THROUGH SOIL CONSERVATION
Modern farm machinery can plant crops without disturbing soil (no-till and minimum tillage.
Conservation-tillage farming:
Increases crop yield.
Raises soil carbon content.
Lowers water use.
Lowers pesticides.
Uses less tractor fuel.

33. SUSTAINABLE AGRICULTURE THROUGH SOIL CONSERVATION
Terracing, contour planting, strip cropping, alley cropping, and windbreaks can reduce soil erosion.
Figure 13-16

34. SUSTAINABLE AGRICULTURE THROUGH SOIL CONSERVATION
Fertilizers can help restore soil nutrients, but runoff of inorganic fertilizers can cause water pollution.
Organic fertilizers: from plant and animal (fresh, manure, or compost) materials.
Commercial inorganic fertilizers: Active ingredients contain nitrogen, phosphorous, and potassium and other trace nutrients.

35. THE GREEN REVOLUTION AND ITS ENVIRONMENTAL IMPACT
Since 1950, high-input agriculture has produced more crops per unit of land.
In 1967, fast growing dwarf varieties of rice and wheat were developed for tropics and subtropics.

36. THE GREEN REVOLUTION AND ITS ENVIRONMENTAL IMPACT
Lack of water, high costs for small farmers, and physical limits to increasing crop yields hinder expansion of the green revolution.
Since 1978 the amount of irrigated land per person has declined due to:
Depletion of underground water supplies.
Inefficient irrigation methods.
Salt build-up.
Cost of irrigating crops.

37. THE GREEN REVOLUTION AND ITS ENVIRONMENTAL IMPACT
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.

38. Biodiversity Loss Soil Air Pollution Human Health Water
Loss and degradation of grasslands, forests, and wetlands
Erosion
Water waste
Greenhouse gas emissions from fossil fuel use
Nitrates in drinking water
Loss of fertility
Aquifer depletion
Salinization
Increased runoff and flooding from cleared land
Pesticide residues in drinking water, food, and air
Other air pollutants from fossil fuel use
Waterlogging
Fish kills from pesticide runoff
Desertification
Sediment pollution from erosion
Contamination of drinking and swimming water with disease organisms from livestock wastes
Greenhouse gas emissions of nitrous oxide from use of inorganic fertilizers
Figure 13.18
Natural capital degradation: major harmful environmental effects of food production. According to a 2002 study by the United Nations, nearly 30% of the world’s cropland has been degraded to some degree by soil erosion, salt buildup, and chemical pollution, and 17% has been seriously degraded. QUESTION: Which item in each of these categories do you think is the most harmful?
Fish kills from pesticide runoff
Killing wild predators to protect livestock
Surface and groundwater pollution from pesticides and fertilizers
Loss of genetic diversity of wild crop strains replaced by monoculture strains
Belching of the greenhouse gas methane by cattle
Bacterial contamination of meat
Overfertilization of lakes and rivers from runoff of fertilizers, livestock wastes, and food processing wastes
Pollution from pesticide sprays
Fig , p. 285

39. THE GENE REVOLUTION
To increase crop yields, we can mix the genes of similar types of organisms and mix the genes of different organisms.
Artificial selection has been used for centuries to develop genetically improved varieties of crops.
Genetic engineering develops improved strains at an exponential pace compared to artificial selection.
Controversy has arisen over the use of genetically modified food (GMF).

41. The Terminator Gene
A genetically modified crop which has a gene to cause the plant to become sterile after the first year

42. Grazing on Rangelands
Overgrazing occurs when the carrying capacity is exceeded. It can cause severe damage to lands
It is important to properly manage livestock, including using appropriate lands for gazing and keeping livestock at a sustainable density

43. SOLUTIONS: SUSTAINABLE AGRICULTURE
Three main ways to reduce hunger and malnutrition and the harmful effects of agriculture:
Slow population growth.
Sharply reduce poverty.
Develop and phase in systems of more sustainable, low input agriculture over the next few decades.

44. Sustainable Organic Agriculture
Solutions
Sustainable Organic Agriculture
More
Less
High-yield polyculture
Soil erosion
Soil salinization
Organic fertilizers
Aquifer depletion
Biological pest control
Overgrazing
Overfishing
Integrated pest management
Loss of biodiversity
Efficient irrigation
Loss of prime cropland
Perennial crops
Figure 13.33
Solutions: components of more sustainable, low-throughput agriculture based mostly on mimicking and working with nature. QUESTION: Which four solutions do you think are the most important?
Food waste
Crop rotation
Subsidies for unsustainable farming and fishing
Water-efficient crops
Soil conservation
Population growth
Subsidies for sustainable farming and fishing
Poverty
Fig , p. 302

45. Sustainable Agriculture
Results of 22 year study comparing organic and conventional farming.
Figure 13-34

46. Sustainable Organic Agriculture
What Can You Do?
Sustainable Organic Agriculture
• Waste less food
• Eat less or no meat
• Feed pets balanced grain foods instead of meat
• Use organic farming to grow some of your food
Figure 13.35
Individuals matter: ways to promote more sustainable agriculture. QUESTION: Which three of these actions do you think are the most important?
• Buy organic food
• Eat locally grown food
• Compost food wastes