1. Chapter 15: Food and Agriculture

2. Humans and Nutrition Uses for food: (1) source of energy.
(2) source of materials for building and maintaining body tissues.
Nutrients needed by the body: carbohydrates, lipids, proteins, vitamins, and minerals.

4. Malnutrition = do not eat enough calories or do not eat a variety of foods to provide the body with what it needs
ex. Humans need 8 essential amino acids. In some parts of the world, where mainly corn and rice are consumed, the people may consume some protein from the food but they will lack needed essential amino acids, vitamins, and minerals. This is known as “protein-energy malnutrition”.

5. Sources of Nutrition Diet = amount and type of food a person eats.
Healthy diet = right amount of nutrients, minerals, and vitamins.
All over the world, people eat diets that are high in carbohydrates.
Grains (high in carbs) =produced in the greatest amounts worldwide
Other common foods = fruits, vegetables, nuts and meats, and other foods rich in protein and fats.

6. Sources of Nutrition

7. Diets Around the World
People worldwide generally consume the same major nutrients and eat the same basic kinds of food.
Diets vary by region.
People in more developed countries tend to eat more food and a larger proportion of proteins and fats than people in less developed countries.
In US, ½ of calories consumed come from meat, fish, and oil.

8. Diets Around the World

9. Staple Foods Around the World
Rice is the most important staple food by half of the world’s population, especially Asia.
China and India- staple is wheat in the form of noodles, buns, and flatbreads.
Central America- cornmeal is more important
European countries- potatoes and bread grains (wheat and rye)
Ethiopia- millet (cereal grass) and buckwheat are staples

10. The Ecology of Food
As the population keeps growing, farmlands and suburbs are replacing forests and grasslands.
Maintaining natural ecosystems has become difficult and the different forms of agriculture have different impacts on the environment.

11. Food Efficiency
The efficiency of a given type of agriculture is a measure of the quantity of food produced on a given area of land with limited inputs of energy and resources.
An ideal food crop is one that efficiently produces a large amount of food with little negative impact on the environment.

12. Food Efficiency con’t.
On average, more energy, water, and land are used to produced a Calorie of food from animals than to produce a Calorie of food from plants.
Animals that are raised for human use are usually fed plant matter, but because less energy is available at each level on a food chain, only about 10 percent of the energy from the plants gets stored in the animals.

13. Food Efficiency con’t.
Land can usually produce more food for humans when it is used to grow plants than when it is used to raise animals.
The efficiency of raising plants for food is one reason why diets around the world are largely based on plants.
However, meat from animals generally provides more nutrients per gram than most food from plants.

14. Old and New Foods
Researchers hope to improve the efficiency of food production by studying plants and other organisms that have high yield.
Yield = amount of crops produced per unit of area.
Researchers are interested in organisms that can thrive in various climates and that do not require large amounts of fertilizer, pesticides, or fresh water.

15. World Food Problems Malnutrition today is mostly due to poverty.
subsistence farmers : work tiny plots to feed their families and sell locally; usually do not have access to enough irrigation
The world’s hungry live mostly in Africa, Asia, and the mountains of South America.

16. More Income and More Food
Extreme poverty numbers (those who make <$1 a day) have declined by ½ billion since 1980 due to rapid economic development in East Asia, especially China and India.
Although grain production has increased, it is not growing as fast as the population.
Future needs: abolish poverty and increase productivity of subsistence farmers.

17. World’s Food Problems

18. Unequal Distribution of Food
If all the food in the world today were divided equally among the human population, no one would have quite enough food for good health.
But food is not divided equally, and malnutrition is largely the result of poverty. Even in the United States, many poor people suffer from malnutrition.
Wars and political strife can also lead to malnutrition because they interrupt transportation systems.

19. Droughts and Famines
Drought = prolonged period when rainfall is below average,
crops grown without irrigation may produce low yields or fail entirely.
A drought is more likely to cause famine in places where most food is grown locally.
If a drought occurs, there may be no seed to plant crops the following year. The effects of a drought can continue for years.

20. Droughts and Famines
People in a given area can usually survive one crop failure. They may have saved enough food from previous seasons, or they may have systems for importing food from elsewhere.
But several years of drought cause severe problems for any area of the world.
For example, after a long drought, the soil may be less able to support the production of food crops.

21. The Green Revolution
: rice production in India doubled & wheat production in Mexico increased 8-fold without increasing the area of farmland used.
Results of the green revolution:
(1) new varieties of grain
(2) reduction in food prices
(3) improved lives of millions of people.

22. Limitations of the Green Revolution:
(1) most increases only came from large farms, subsistence farmers had no money to get water & chemicals needed for new varieties of crops.
(2) Subsistence farmers do not have access to machinery.
Subsistence farmers need small-scale irrigation systems and high-value crops such as vegetables and fruits that they can sell.

23. Section 2 Crops and Soil

24. Agriculture: Traditional and Modern
Arable land is used to grow crops. 10% of Earth’s surface.
Traditional Agriculture:
(1) uses plows pulled by livestock or pushed by farmers.
(2) organic fertilizers (manure)
(3) irrigation through ditches.
(4) weeds removed by hand or machines.

25. Agriculture: Traditional and Modern
Modern Agriculture:
(1) uses machinery powered by fossil fuels for plowing and harvesting
(2) synthetic chemical fertilizers
(3) overhead sprinklers and drip irrigation systems
(4) synthetic chemicals to kill pests

26. Fertile Soil: The Living Earth
Fertile soil can support the growth of healthy plants.
Components of fertile soil (topsoil):
living organisms, rock particles, water, air, and organic matter (decomposing organisms)

27. Soil Formation Steps in soil formation:
1. Rock is broken down by wind, water, and chemical weathering (reaction of minerals in rock with substances such as water).
2. Temperature changes and moisture cause rock to crack and break apart. Plant seeds can take root in the these cracks.
3. Minerals are added to the soil from the rocks broken down. More layers of soil are added as plants and living organisms that move in die and decompose.

28. Organisms Found in Soil

29. Layers of Soil

30. Soil Erosion: A Global Problem
Crops cannot be grown without topsoil.
½ of the original topsoil in the US has been lost due to erosion in the past 200 years.
Most farming practices increase the rate of erosion.

31. Soil Conservation Methods used to reduce soil erosion:
1. terracing- multiple, small, level fields.
2. contour plowing- plowing across the slope instead of up and down the slope.
3. Leaving strips of vegetation instead of plowing entire slope.
4. Drip irrigation instead of overhead.
5. Planting cover crops

32. Soil Conservation con’t.
6. Leaving stubble from harvested crops.
7. Planting trees alongside fields to serve as windbreaks.
8. No-till farming- harvesting crop without turning over soil.
9. Strip cropping- planting different crops in the same field.

33. Terracing

34. Contour Plowing

35. Land Degradation
Human activities or natural processes damage the land so that it can no longer support a ecosystem.
ex. The Dust Bowl- 1930’s, Great Plains region of US
Desertification may occur in dry climates and cause arid and semiarid areas to become even more desertlike.
ex. page 414 Sahel region of northern Africa

36. Enriching the Soil Methods of enriching the soil:
1. organic matter- manure, leaves, etc.
2. inorganic fertilizers- contain nitrogen, phosphorus, and potassium.
3. modern methods may include adding both organic and inorganic matter fertilizers by adding compost (decomposed organic material) and chemical fertilizers at the same time.

37. Salinization Accumulation of salt in soil
Common in areas irrigated with river or groundwater (saltier than rain water)
Soil may become too salty to support plant growth

38. Pest Control North America- 13% of all crops eaten by insects
Pests destroy 33% of the world’s potential food harvest.
A pest is any organism that occurs where it is not wanted or that occurs in large enough numbers to cause economic damage.

39. Wild plants have more protection from pes than crop plants.
(1) more difficult to locate by predators
(2) predators of the pest may live around the wild plants.
(3) poisonous chemicals to repel pests.

40. Pesticides Used to kill insects, weeds, and other crop pests.
Problems with pesticides:
(1) over time the pest may evolve resistance.
(2) dangerous to humans
(3) They may be persistent pesticides. These are pesticides that do not break down into harmless chemicals when they enter the environment. Instead, they keep accumulating.
ex. DDT

41. Pesticide Resistance

42. Biological Pest Control: Using living organisms to control pests
(1) pathogens such as bacteria ex. Bacillus thuringienis (Bt) – kill caterpillars of moths and butterflies
(2) plant defenses- chemical compounds that repel pests and also physical barriers, such as tougher skin.
(3) chemicals from plants that are defensive yet are biodegradable. May be used in insect sprays designed for home use.
(4) Disrupting Insect Breeding- Treating plants with pheromones. Page 420

43. Integrated Pest Management
Goal: reduce pest damage to a level that causes minimal economic damage.

44. Integrated Pest Management
Different programs created for different crops.
Involves mix of farming methods with biological pest control and chemical pest control.
Steps
1. biological control w/natural predators, pathogens, and parasites of the pest
2. cultivation controls-vacuuming insects off plants
3. insecticides used in small amounts

45. Engineering a Better Crop
Genetic engineering is used to create desirable traits in crops.
Involves isolating genes for desirable traits found in one organism and implanting them in another organism.
Plants created this way are known as genetically modified (GM) plants.

47. Implications of Genetic Engineering
In the United States, we now eat and use genetically engineered agricultural products everyday.
Many of these products, however, have not been fully tested for their environmental impacts.
Some scientists warn that these products will cause problems in the future.

48. Sustainable Agriculture
Farming that conserves natural resources and helps keep the land productive
Sustainable agriculture involves planting productive, pest-resistant crop varieties that require little energy, pesticides, fertilizer, and water.

49. Farming Practices
Research the farming practices of the country that you drew. Identify how that country farms, do they use pesticides and herbicides. Are there regulations on the use of these items. What type of things do they farm?
Compare and contrast the farming practices of your country to the United States.

50. Section 3 Animals and Agriculture
In the past, animal protein was obtained by hunting and fishing. Today, most people get animal protein from domesticated species.
Domesticated describes organisms that have been bred and managed for human use.

51. Food from Water
Because fish are an important food source for humans, the harvesting of fish has become an important industry worldwide.
However, when too many fish are harvested over a long period of time, ecological systems can be damaged.

52. Food from Water
The North Atlantic cod fishery has collapsed because too many fish were harvested over time.

53. Overharvesting
Overharvesting is the catching or removing from a population more organisms than the population can replace.
Many governments are now trying to stop overharvesting. No-fishing zones have been created, so that fish populations can recover.

54. Aquaculture
Aquaculture is the raising of aquatic plants and animals for human use or consumption.
Fish and other aquatic organisms provide up to 20 percent of the animal protein consumed worldwide.
Aquaculture may be one solution to the overharvesting of fish and other organisms in the world’s oceans.

55. Aquaculture
Fish farms generally consist of many individual ponds that each contain fish at a specific stage of development. Fish grow to maturity in the ponds and are then harvested.
Fish ranches raise fish to a certain age, release them to the ocean, and then harvest the adults when they return to their birthplace to breed.

58. Aquaculture
As with other methods of food production, however, aquaculture can cause environmental damage if not managed properly.
1. Aquatic organisms can produce a large amount of waste, which can be a source of pollution.
2. Because aquaculture requires so much water, the process can deplete local water supplies.

59. Livestock
Livestock is the term given to domesticated animals that are raised to be used on a farm or ranch or to be sold for profit.
Populations of livestock have changed dramatically in the last 40 years.
Large livestock operations produce most of the meat that is consumed in developed countries.

60. Livestock

61. Livestock
In developing countries, livestock not only provides leather, wool, eggs, and meat, but also serve other functions.
Some livestock are used as draft animals to pull carts and plows.
Other livestock provide manure as the main source of plant fertilizer or fuel for cooking.

62. Ruminants
Ruminants are cud-chewing mammals that have a three- or four-chambered stomach.
ex. Cattle, sheep, and goats are examples of ruminants.
Cud is the food that these animals regurgitate from the first chamber of their stomachs and chew again to aid digestion.
When we eat the meat of ruminants, we are using them to convert plant material, such as grass stems and woody shrubs, into food that we can digest—such as beef.

64. Ruminants
Humans have created hundreds of breeds of cattle that are suited to life in different climates.
Worldwide meat production per person has increased significantly since 1950.

65. Poultry
Chickens are a type of poultry, domesticated birds raised for meat and eggs.
Since 1961, the population of chickens worldwide has increased to a greater percentage than the population of any other livestock.
In more-developed countries, chickens and turkeys are usually raised in factory farms.