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. BrownPresident, Worldwatch Institute

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

• Efforts by us to feed more people in this world are causing this environmental change, making it more difficult to feed all the people

What People Eat

• 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

Why People go Hungry

• Increasing populations requires more food; food production is increasing but amount of food per person is not increasing

• It 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)

• Droughts can contribute to starvation as well; combined with war or a break in transportation can result in a famine (food shortages in a wide spread area)

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

• Problems: need the right kind of fertilizers and pesticides, and irrigation water

• 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

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

9.2: 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

Farming

• 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

Fertile Soil

• Soil that can support the rapid growth of healthy plants is called fertile soil; most root in topsoil (loose soil comprised of rock particles, water, air and organic matter)

• 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

• It can take thousands of years to form a few centimeters of soil

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

Desertification

• 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

• 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. Resulting in desert rather than productive farm/grazing land

Soil Conservation

• There are many ways to conserve topsoil and reduce erosion: 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

• Use organic material rather than inorganic fertilizers (restores soil): compost or manure

• Change the way farmland is plowed…rather that plowing under, plant new crops through the remains of the old plants allowing less erosion and natural organic matter to be added to the soil

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

Preventing 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

• 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

Old and New Foods

• Researchers are investigating ancient plants and looking at new varieties of plants

• Looking for plants betters adapted to different climates and produce high yields without large amounts of fertilizers, pesticides and 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

9.3: 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, 1/3 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

• Over the last 50 years, many new chenical pesticides have been developed and farmers have begun to rely on them to protect their crops

Drawbacks of Pesticides

• Unfortunately, the new pesticides affect a lot more than just the pests that they were designed to kill

• They can also harm people and wildlife

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

• Workers in pesticide factories may become ill, as well as the people living near these factories, from accidental chemical leaks

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

Pesticide Resistance

• Spraying large amounts of pesticides is NOT the most effective way to get rid of pests; it usually makes it worse; pests evolve resistance (ability to tolerate a particular pesticide)

• How? Some of the insects have a gene that protects them from a pesticide; they go on to reproduce, passing on that resistance gene to their offspring

• More than 500 species of insects have developed resistance to pesticides since the 1940s

Biological Pest Control

• Because resistance evolves so rapidly, farmers and pest-control companies are using fewer pesticides

• Turning to biological pest control (using living organisms or naturally produced chemicals to control pests

• Generally do no harm anything but the particular pest it is designed to control, resistance takes longer to evolve

Predators and 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)

Plant Defenses

• Cross breeding some plant varieties to produce crops that have their own defenses

• Ex: production of chemical compounds that repel pests; tougher skin

Chemicals from Plants

• Make use of plants’ defense chemicals

• Ex: extracting chemicals from the chrysanthemum and sell it as a pesticide; they are biodegradeable

Disrupting Insect Breeding

• 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 xrays, making them sterile; when they mate, eggs do not get fertilized

L/O/G/O

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