Presentation is loading. Please wait.

Presentation is loading. Please wait.

L/O/G/O Chapter 9: FOOD “In simplest terms, agriculture is an effort by man to move beyond the limits set by nature.” Lester R. Brown President, Worldwatch.

Similar presentations

Presentation on theme: "L/O/G/O Chapter 9: FOOD “In simplest terms, agriculture is an effort by man to move beyond the limits set by nature.” Lester R. Brown President, Worldwatch."— Presentation transcript:

1 L/O/G/O Chapter 9: FOOD “In simplest terms, agriculture is an effort by man to move beyond the limits set by nature.” Lester R. Brown President, Worldwatch Institute

2 9.1: Feeding the People of the World Ethiopa, 1985; people were starving (lack of rain, soil degradation, war); when rain came, it washed away millions of tons of soil into the rivers; resulted in 6,000 sq. mi. of desert Events like this present frightening pictures of how difficult it is to feed the Earth’s growing population Modern agricultural practices provide most of the world’s population with enough food to survive; however, efforts by us to feed more people in this world are causing this environmental damage, making it difficult to grow crops to feed all the people

3 Humans and Nutrition We must consume organic compounds in order to survive (carbohydrates, proteins, lipids); we also need vitamins and minerals to help our bodies function properly Food is used as a source of energy and for building and maintaining our bodies; lack of enough food will result in sickness or death; starving people die from disease that our bodies cannot fight off; malnutrition is a result of not eating enough of the necessary nutrients

4 Sources of Nutrition A person’s diet is the type and amount of food a person eats. Healthy diets are ones that maintain a balance of the right amounts of nutrients, minerals and vitamins. Most parts of the world, people eat large amounts of foods high in carbohydrates (rice, potatoes, bread); foods produced in the greatest amounts are grains (plants whose seeds are rich in carbohydrates); aside from grains, most people eat fruits, vegetables and small amounts of meats, nuts and other foods rich in fats and proteins.

5 Diets Around the World Worldwide, people generally consume the same major nutrients and eat the same basic kinds of foods; however diets can vary from region to region. More developed countries tend to eat more food and larger proportions of proteins and fats than people in less developed countries. ex: In US, almost half the calories consumed come from meat, fish and oil; In Japan, their diet traditionally consists of a mix of rice, vegetables and seafood

6 The Ecology of Food As human population grows, farm land replaces forests and grasslands Feeding all the people of the world and still maintaining natural ecosystems is becoming more difficult Different types of agriculture present different environmental impacts and different levels of efficiency

7 Food Efficiency The measure of the quantity of food produced on a given area of land with limited inputs of energy and resources An ideal food crop would be one that efficiently produces a large amount of food with as little negative impact on the environment as possible. More energy, water and land are used to produce food from animals than food from plants; plants are used to feed the animals who produce food for humans; less energy is available at each level of the food chain (10% is stored in the animals), therefore more food can be produced for humans when it is used for humans rather than for feed for animals One reason why diets around the world are largely based on plants (it is more efficient and more can be produced per acre); however, meat from animals provides more nutrients per gram than most food from plants

8 Old and New Foods Researchers are investigating ancient plants and looking at new varieties of plants Looking for plants better adapted to different climates and produce high yields without large amounts of fertilizers, pesticides and fresh water Studying plants that have not been widely used for food in the past but may be useful Ex: Amaranth – sacred food of the Aztecs and Glasswort – can be grown in saline soil

9 9.2: World Food Problems Some people become malnourished because there is simply not enough food for them; more food is needed each year to feed the world’s growing population World food production has been increasing for decades, but now food production is not increasing as fast as human population is increasing

10 Unequal Distribution Food is not equally distributed throughout the world; wealthy people have an abundance; poor people have much less than they need Malnutrition occurs everywhere in the world; starvation results when food cannot be transported to where it is needed (transportation lines break down, wars) During war, even if food is available, a break in transportation can result in a famine (food shortages in a wide spread area)

11 Droughts and Famines Droughts occur when there is a prolonged period when the average rainfall is below average; more likely to cause famine in places where most food is grown locally than in places where most food is imported Crops grown without irrigation may produce low yields or fail altogether; if drought occurs, there may be no seed to plant crops the following years (and can continue for many years.) People can usually survive through one season of crop failure (food saved from previous season or by importing food in); if drought lasts for several years, more serious problems can occur (ex: soil may be less able to support the production of food crops)

12 The Green Revolution In an effort to increase crop yields, new varieties of grain and farming methods were introduced between 1950 and 1970, resulting in a much greater yield (ex: Mexico increased wheat production eight-fold; India doubled its production of rice); changed the lives of millions of people Problems: need the right kind of fertilizers and pesticides, and irrigation water for large yields of grain; additionally, the machinery, irrigation and chemicals required by new crop varieties can degrade the soil if they are not used properly

13 The Green Revolution…con’t As a result, overuse of fertilizers and pesticide have caused a decrease in green revolution crops; grain production in US has decreased since 1990, partly because the amount of water used for irrigation has decreased during the same period Subsistence farmers only grow enough for their families and can’t afford the proper tools; therefore, only large scale farms grow food to be sold (they are at their max now); large use of fertilizers and pesticides are polluting the environment; machinery uses a large amount of energy

14 Political Changes Making peace in war-torn countries is essential toward supplying its people with enough food Donated food can then be distributed more effectively Sustainable farming techniques can be learned

15 9.3: Agriculture and Soil Earth has a limited amount of arable land (fertile) to grow crops; decreases every year (1/5 from 1985 to 2000) 371 million acres of farmland will be covered by houses and industry; 334 million acres will become unusable for farming because soil will be damaged This shortage of fertile land threatens our ability to feed the human population

16 Agriculture: Traditional and Modern Plowing, fertilization, irrigation and pest control began with the earliest farmers; animals or people pulled plows through the soil (mixes up the nutrients, loosens soil and uproots weeds) Organic fertilizers (manure) enriched soil; digging ditches supplied water; weeds were dug up by hand – still used today in many places Large farms in industrialized countries use machinery (to plow and harvest); synthetic fertilizers are used to enrich soil; overhead drips/ sprinkles for irrigations; chemicals kill pests

17 Fertile Soil: The Living Earth Soil that can support the rapid growth of healthy plants is called fertile soil; most root in topsoil (rich in organic matter; loose soil comprised of living organisms, rock particles, water, air and organic matter) Most soil forms when rock is broken down into smaller and smaller fragments by wind, water and chemical weathering (when minerals in the rock react chemically with substances such as water to form new materials); temperature changes and moisture cause rock to crack and break apart, making smaller particles where pioneer species can take root and grow; It can take thousands of years to form a few centimeters of soil Living organisms (earthworms, insects and other small animals) play an important role in breaking up the soil; also the decomposers (fungi, bacteria, microorganisms) when they break down detritus One clear way to know if soil is fertile is to look for earthworms. There are several layers of soil which lie under the topsoil; bottom layer is called the bedrock (solid rock from which soil originally forms)

18 Topsoil Erosion: A Global Problem Soil that has been formed is being lost to erosion In US, about ½ of the topsoil has been lost to erosion in the past 200 years; worldwide, 11% of the soil has been eroded in the past 45 years Soil erosion is ranked as one of the most serious ecological problems we face today Some farming techniques today contribute to the erosion (blowing wind and rain washing it away) Harvesting removes roots and other organic matter that holds the soil together; clearing forests for lumber; water runoff carries away the soil

19 Land Degradation Land Degradation happens when human activity or natural processes damage the land so that it can no longer support the local ecosystem Loss of topsoil, especially in dry areas, is severe; if it deteriorates so much the land becomes desert-like (desertification); worldwide an area the size of Nebraska becomes desert every year; this process is causing arable land to disappear Ex: In Northern Africa, if the appropriate method of rotating the crops and grazing their animals were observed, the land would adequately support the people of that region; however, today, increased overuse of the land and large numbers of grazing animals have left the land barren. Because of the overgrazing, the land can no longer support the plants that held the topsoil in place, resulting in desert rather than productive farm/grazing land

20 Soil Conservation There are many ways to conserve topsoil and reduce erosion; soil usually erodes downhill Pay attention to the slope of the land when planting, contour plowing (plowing across the slope of the hill), leaving strips of vegetation running across the hillside, not farming in an area where it is very hilly; terracing, multiple, small, level fields used on a hillside; often used for wine grapes and coffee Change the way farmland is plowed…ex: no-till farming - rather that plowing under, plant new crops through the remains of the old plants allowing less erosion (reduces soil erosion to 1/10 that of traditional methods), saves time; however, there are disadvantages to this method: soil may become too densely packed over time and therefore, lower crop yields over time.

21 Enriching the Soil Traditional fertilizers: organic matter such as manure and leaves were added to the soil; as it decomposes, it adds nutrients to the soil and improves the texture of the soil Inorganic fertilizers that contain nitrogen, phosphorous, and potassium have changed farming methods; without these fertilizers, world food production would be less than half of what it is today Over the past 50 years, use of such fertilizers has rapidly increased; if soil erosion would occur in areas where these fertilizers (inorganic) are being used, waterways will be at risk of being polluted A modern method of enhancing soil is to use both organic and inorganic fertilizers by adding compost (partly decomposed organic material) and chemical fertilizers to the soil Compost can be purchased (composted cow manure) in stores; yard waste and crop waste can be used

22 Salinization Salinization is the accumulation of salt in the soil; salt is in the soil naturally, but when it is irrigated with water from rivers or groundwater, it builds up and makes the land unusable; rainwater contains less salt than groundwater Major issue in places such as California and Arizona which have low rainfall and have naturally salty soil; soil is salty because the water used for irrigation is saltier than rainwater, when it evaporates it leaves behind the salt; over time it will become too salty to plant Ways to slow soil salinization: irrigation canals, water soil heavily prior to planting seeds, plant salt tolerant crops or trees to reclaim the land (shade trees will reduce evaporation from the soil surface; fallen leaves add organic matter to the soil) Total restoration of the land takes decades

23 9.4: Pest Control In North America, 13% of all crops are destroyed by insects; tropical climates enough greater damage; Kenya lose 25% of their crops from insects; worldwide, 33% of the world’s potential food harvest is destroyed Wild plants have more protections from pests than do crop plants; wild plants are scattered, therefore, harder to find, have evolved defenses and have pest predators living in or around them; crops plants are all in one location, a one-stop food source

24 Pesticides Over the last 50 years, many new chemical pesticides have been developed and farmers have begun to rely on them to protect their crops; used to kill insects, weeds and other crop pests Unfortunately, the new pesticides affect a lot more than just the pests that they were designed to kill They can also harm people, wildlife and beneficial plants and insects

25 Pesticide Resistance If large amounts of pesticides are used frequently, over time, the pest problem will become worse. Pest populations evolve to become resistant and survive through exposure to that particular pesticide More than 500 species of insects have developed resistance to pesticides since the 1940’s

26 Health Concerns Many pesticides can cause people to get sick Ex: California has seen an increase in cancer rates among children in areas which grow fruits and vegetables with high pesticide use; people applying the pesticides have to follow safety guidelines to protect themselves from contact with these chemicals Workers in pesticide factories may become ill, as well as the people living near these factories, from accidental chemical leaks

27 Pollution and Persistence Pesticides can become problematic for humans and wildlife because they are persistent (don’t break down rapidly into harmless substances when they enter the environment), they accumulate in the water and soil Ex: DDT – used in the 1940”s to kill mosquitoes (malaria, lice that spread typhus); DDT is very persistent, gradually accumulates in bodies of water, absorbed by fish, and then eaten by birds; resulted in increased levels of DDT in bodies; eggs were so thin they broke when sat on (penguins, pelicans, peregrine falcons, eagles); many became endangered DDT banned in U.S.; but continues to remain in the environment

28 Biological Pest Control Because resistance evolves so rapidly, farmers and pest- control companies are using fewer pesticides and practicing some form of pest management Turning to biological pest control (using living organisms or naturally produced chemicals to control pests); every pests has enemies in the wild and those enemies can be used to control pest populations (ex: In India (mid-1800’s), American prickly pear cactus had been introduced into India to feed insects that are used to make a valuable red dye; Cactus had no natural enemies, grew and spread. Plants were finally controlled by the introduction of an American beetle that eats cactus Generally, do no harm anything but the particular pest it is designed to control, resistance takes longer to evolve

29 Pathogens Releasing a natural predator or parasite is one method of biological control Pathogens (organisms causing disease) is another method Ex: Bacillus thuringensis (bacterium) kills larvae (caterpillars of moths and butterflies)

30 Plant Defenses Cross breeding some plant varieties to produce crops that have their own defenses Tomato plants labeled “VNT” means they are resistant to certain fungi, worms and viruses Ex: production of chemical compounds that repel pests; tougher skin

31 Chemicals from Plants Another type of biological pest control is to make use of plants’ defense chemicals (Ex: extracting chemicals from the chrysanthemum and sell it as a pesticide) They are biodegradable (can be broken down by bacteria and other decomposers) and are designed for use in the home because they do not harm humans or pets

32 Disrupting Insect Breeding Growth regulators are chemicals that interfere with some stage of a pest’s life cycle (ex: dogs – flea pills prevent flea eggs from developing) Pheromones - chemicals produced by an organism that affect the behavior of another - are also used Ex: female moths find mates by releasing pheromones that attract males, farmers treat crops with those pheromones to confuse the males (interferes with mating) Another example: treat male insects with x-rays, making them sterile; when they mate, eggs do not get fertilized

33 Integrated Pest Management This is a modern method of controlling pests on crops (see handout) Not designed to eliminate pest populations but to reduce pest damage to a level that causes minimal economic damage; program is designed for specific crops; can include a mix of farming methods (biological pest control and chemical pest control) Used at specific times in the growing season, fields are monitored at all times during the growing season, when significant pest damage is found, pest is identified and program to control the pest is created Biological methods are the first methods used to control the pest (natural predators, pathogens, parasites of the pest) Cultivation controls can also be used As a last resort, insecticide may be used; changed over time so they do not have the ability to evolve resistance

34 Engineering a Better Crop Plant breeding has been used since agriculture began; farmers select best tasting tomato plants, least pest damage, save seeds and use them the next year; consequently, these plants are more likely have genes for large, tasty tomatoes and resist pest A faster way to get the same result is to use genetic engineering (genetic material in a living cell is modified for medical or industrial use); they will isolate genes from one organism and implant it into another to get the desirable trait they are looking for (ex: pest resistant) Plants resulting from genetic engineering are called genetically modified plants (GM) (See handout for steps used to produce a GM plant)

35 Implications of Genetic Engineering In US, we now eat and use genetically engineered agricultural products every day Many have not been fully tested for environmental impacts; could cause problems in the future (ex: genes are sometimes transferred from one species to another in the wild) GM corn plant could pass its genes to a wild corn plant; then, that corn plant could not be eliminated by a pesticide

36 Sustainable Agriculture How can we feed the world’s population without depleting the world’s resources? Low-input farming – farming without using a lot of energy, pesticides, fertilizers and water Ex: organic farming – farming without the use of synthetic materials, use manure, compost and keep the land planted at all times (reducing erosion), alternating crops Aquaculture – “fish farming” or raising fish in artificial environments

37 Section 9.5: Animals and Agriculture We have seen that the total energy needed to grow plants for food is much less than the energy needed to raise animals as food. Most people will include some animal proteins in their diets because they contain more essential amino acids than proteins found in plants; animal proteins have been the basis of life for centuries; many populations have traditionally obtained most of their proteins from fish and seafood. Ancestors hunted and fished; today, animal proteins are obtained from domesticated species (about 50 species are domesticated – bred and managed for human use) ex: chicken, sheep, cattle, honey bees, silkworms, fish, shellfish, goats, pigs, water buffalo

38 Food from Water Fish are an important food source for humans Harvesting fish has become an important industry worldwide Damage to ecological systems can occur when too many fish are harvested over a long period of time.

39 Overharvesting Catching or removing too many of any one organism from a population without giving them time to be replenished is called overharvesting. Governments are now attempting to stop overharvesting by creating no-fishing zones so the fish populations can recover; surrounding areas have seen improvements after a few years These areas are necessary if fish markets throughout the world are to prosper

40 Aquaculture Fish and other aquatic organisms provide up to 20% of the animal protein consumed worldwide; however, overharvesting is reducing the number of fish and other organisms in the oceans Aquaculture (raising of aquatic organisms for human use and consumption) is rapidly increasing and will continue to be an important source of protein in the human diet Not a new idea; began in China about 4000 years ago; they lead the world in using aquaculture Different methods of aquaculture include: oyster farms and fish farms-ponds that contain fish at specific stages of development by using clean water to bring in oxygen and remove CO 2 and fecal matter, grow until maturity and then are harvested

41 Aquaculture…con’t Another type of aquaculture is known as ranch. Fish, like salmon, as raised until they reach a certain age, then are released into the wild. Salmon return to their birthplace to reproduce, when they return, they are captured and harvested. Most of the catfish, oysters, salmon, crayfish and rainbow trout eaten in the US are products of aquaculture; worldwide, about 23% of seafood comes from aquaculture This method can cause environmental damage is not managed properly (ex: aquatic organisms can create a large amount of waste, can deplete local water supplies, wetland areas can be destroyed when aquaculture operations are located within them)

42 Livestock Domesticated animals that are raised to be used on a farm or ranch or to be sold for profit are called livestock Global livestock populations have changed dramatically in the last 40 years; meat production per person has increased worldwide since 1950 Pig farming produces most of the meat consumed in developed countries; in developing countries. Livestock also provided leather, wool, eggs, meat and many other functions Some livestock are used as draft animals (to pull carts and plows), while others provide manure as the main source of plant fertilizer or as a fuel for cooking

43 Ruminants Cattle, sheep and goats are ruminants (cud-chewing mammals that have three or four chambered stomachs Cud is the food these animals regurgitate from the first chamber of their stomachs and chew again to aid digestion; also have microorganisms in their intestines which allow them to digest plant material Humans have created hundreds of breeds of cattle suited for specific environments; they are most common in North America, India and Africa; not always slaughtered for meat In Africa, herders drink milk and blood from their cattle, rarely kill them for meat; India has almost 1/5 of the world’s cattle, they are sacred to Hindus and are not killed or eaten, they are used for milk, dung and as draft animals

44 Poultry Chicken populations worldwide have increased by a greater percentage than any other population of livestock since 1961. In more-developed countries, chickens and turkeys are usually raised in factory farms; these farms have been criticized because of the cramped, artificial environments these animals live in Fewer ducks and geese are raised worldwide than chickens but in some areas ducks and geese are economically important. Chinese use ducks for meat and for their waste; waste is used to fertilize rice paddies

45 L/O/G/O Thank You!

Download ppt "L/O/G/O Chapter 9: FOOD “In simplest terms, agriculture is an effort by man to move beyond the limits set by nature.” Lester R. Brown President, Worldwatch."

Similar presentations

Ads by Google