Food, Soil and Pest Management
A look at our current use of agriculture
Key macronutrients in your diet
•Proteins
–Animals and some plants
–Build and repair body tissues
•Carbohydrates
–Wheat, corn, and rice
–Provide short term energy
•Lipids
–Animal fats, nuts, oils
–Build membrane tissues and create hormones
Micronutrients
•Vitamins
–A, C, E, etc.
•Minerals
–Iron, iodine, calcium, etc.
Hunger
•Chronic undernutrition
–Don’t get enough food to meet basic energy needs.
–Most of these people live in developing nations
•Chronic malnutrition
–Deficiencies in key nutrients which makes a person more susceptible to disease
•Famine
–Severe shortage of food in an area followed by mass starvation and economic and social chaos
Deficiencies in Micronutrients
•WHO says that one in 3 people lack a diet rich in one or more vitamins and minerals (particularly iron, Vitamin A,
and iodine)
•Golden Rice (contains beta carotene which the body converts to Vitamin A) may help reduce Vitamin A and iron
deficiencies
–Some critics oppose genetically modified crops; others want evidence of how beta carotene in rice will be converted
to vitamin A in the body
Overnutrition
•Excess of food beyond energy needs which causes excess body fat.
•Major concern in developed nations
•Leads to lower life expectancy, greater susceptibility to disease and illness, and decreased productivity
Where does food come from?
•Our food supply systems depend on a small number of plant and animal species.
Almost half of the calories and
protein people consume are from three types of grain: corn, wheat, and rice.
•3 types of systems which supply our food:
–Rangelands, pastures, and feedlots
–Croplands
–Oceanic fisheries
–
How is Food Produced?
•1) Industrialized agriculture
–Uses heavy equipment, $, large amounts of fossil fuels, water, fertilizers, and pesticides to produce monocultures
(single crops).
–Goal: to increase yield (amount of food produced per unit of land)
–Types:
•Plantation - primarily in tropical countries and involves growing cash crops like bananas, soybeans, coffee, etc. for
export to developed nations
•Greenhouses - used in arid lands to make them productive. Uses large amounts of water and energy.
•Hydroponics - plants are grown with roots in water rather than in a greenhouse. Uses less water than conventional
farming b/c water is recycled.
•2)
Traditional agriculture - used primarily in developing nations.
–Traditional subsistence farming
•Uses human labor and animals to produce enough crops for the family to use.
–Traditional intensive agriculture
•Uses human and animal labor along with fertilizer and water to increase crop yields to feed family and to sell to
others.
Polycultures
•Many traditional farmers grow several crops on the same plot => polyculture.
•Slash and burn agriculture uses this idea. Plots are burned and cleared and then used for growing a variety of crops
for a few years until the nutrients are used up. Then the crops are shifted to new plots and the fields are left fallow for a
period of time.
–Overall reduces erosion, reduces need for water and fertilizer, also reduces need for herbicides and insecticides
Green Revolution
•Using high input industrialized agriculture to increase yields.
•There are three steps:
–1)
–2)
–3)
Develop high yield varieties of key crops
Use large amounts of fertilizers, pesticides, and water
Practice multicropping to increase the number of crops grown on the same plot per year .
Green Revolutions
•First green revolution occurred in the U.S. and other developed nations (1950 to 1970) and dramatically increased
crop yields.
•Second green revolution has used fast growing dwarf varieties of rice and wheat grown in tropical/subtropical
climates and introduced them into India and China and developing countries in Central and South America.
•Between 1950 and 1996, world grain production tripled, but has stabilized/declined since.
Producing new crop varieties
•Cross breeding/artificial selection
–Using traits that plants have and selectively breeding for those traits to develop more desirable crops; slow process;
can only combine traits from species that are genetically similar
•Genetic engineering
–Alters an organisms genetic material by adding, deleting, or changing segments of its DNA to produce desirable traits
or remove undesirable ones; much faster; enable scientists to transfer genes between species that could not breed in
nature =>genetically modified organisms (GMOs)
Controversy over GMOs
•Once GMOs are released into the environment, they are impossible to retrieve.
•Any problems may be unpredictable and harmful toxins may be put in food due to possible plant mutations
•May introduce new allergens in foods
•Lowers genetic diversity
•Can harm beneficial insects and incrase pesticide resistant organisms
Advantages of GMOs
•Need less fertilizer and water and pesticides
•Grow faster
•More resistant to pests, frost, drought, disease
•Higher yields
•Less spoilage
Meat production
•1/2 the world’s meat comes from livestock grazing on grass on unfenced rangelands / enclosed pastures
•The rest are raised in feedlots and confined animal feeding operations where they are fed grain and meal produced
from fish. Typically fattened up for about 4 months before slaughter. Grain is grown on cropland.
•Meat consumption is increasing.
•Estimated that 30% of ice free land is used either directly/indirectly for livestock production and is on the increase.
•As incomes grow in a country, more meat is consumed.
•This increases demand for grains to feed livestock.
•As industrialization increases, there is less cropland.
•China and India are the world’s leading producers of wheat: if trends continue there is no country or combination of
countries that could supply China’s potential food supply deficits.
Eat lower down on the food chain
•Eating the average U.S. based meat diet could support 2.5 billion people
•Follow a Mediterranean diet, feed 5 billion people.
•Cattle are the worst of major livestock (cattle, pigs, chicken, fish) at converting grain into animal protein.
Fish and Shellfish Production
•Fishery
–A concentration of particular aquatic species suitable for commercial harvesting in a given ocean area or inland body
of water.
•Aquaculture
–Raising marine or freshwater species in ponds and underwater cages
•A 2007 report found that
–25% of the world’s ocean fisheries are virtually depleted
–52% have been fully exploited
–77% of commercially valuable fish stocks are overexploited
•Overfishing, pollution, and climate change could cause a worldwide ocean fisheries collapse by 2050.
•Modern fishing fleets use more energy than they provide.
Blue Revolution
•Aquaculture is the world’s fastest growing type of food production.
•There are environmental and economic challenges.
•Dominated by operations that raise herbivorous species like carp and tilapia.
•Good method is to use polyaquaculture which integrates crop growing and aquaculture and produces food to feed fish.
Using grains and fishmeal uses up precious resources and increases demand for cropland.
Pros and Cons of Aquaculture
•Pros
–High efficiency
–High yield in small volume of water
–Reduce overfishing in fisheries
–Low fuel use
–High profits
•Cons
–Needs large inputs of land, feed, and water
–Large waste output
–Can destroy mangroves and estuaries
–Uses grain to feed some species
–Dense populations vulnerable to disease
Controlling Pests
•Pest - any species that interferes with human welfare by competing with us for food, destroying buildings, spreading
disease, etc.
•Only about 100 different species cause most of the crop damage.
•In natural ecosystems, there are natural enemies. By clearing forests, we change the natural checks and balances.
Pesticides
•Chemicals which kill or control organisms which are undesirable.
–Insecticides - insects
–Rodenticides - rodents
–Herbicides - weeds
–Fungicides - fungi
•Plants have developed chemicals to repel or kill other species and have used these for millions of years
•First generation pesticides: we used natural chemicals to discourage pests.
•Second generation pesticides: produced in the laboratory.
–1874: DDT was invented by Paul Muller. Became the most se pesticide
–Silent Spring pointed out dangers of DD
•Broad spectrum pesticides: toxic to many pest and non-pest species (DDT)
•Narrow spectrum agents: effective against a narrowly defined group of organisms
•Persistence: how long a pesticide remains toxic in the environment
•Many of these can be biologically magnified (biomagnified) in food webs. The higher up the food chain you are, the
more concentrated the toxin.
Pros and Cons of Synthetic Pesticides
•Pros
•Save lives
•Increase food supplies
•Profitable
•Work fast
•Safe if properly used
•Cons
•Promote genetic resistance
•Kill natural pest enemies
•Pollute the environment
•Expensive for farmers
•Can harm wildlife and people
Alternatives
•Fool the pest with cultivation practices
•Provide homes for pest enemies
•Implant genetic resistance
•Bring in natural enemies
•Use pheremones
•Use hormones
•Scald pests with hot water
Laws to protect us from pesticides
•EPA
•USDA
•FDA
•Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) - assess health risks of active ingredients in pesticides
•Food Quality Protection Act - reduces allowable levels of pesticide residues in food by a factor of 10 when they may
affect children
Integrated Pest Management
•Uses a sustainable approach to pest management
•Looks at a system as an ecological system
•Uses a combination of cultivation, biological controls, and chemical tools and techniques applies in a carefully
coordinated way
Governmental approaches to influence food production
•Control prices
•Provide subsidies
•Let the marketplace decide
Limits to the Green Revolution
•Without huge inputs of fertilizer, pesticides, and water, most crop varieties used in the Green Revolution are no higher
than those used in traditional agriculture
•Limiting factors include: population growth, poor soils/erosion, water shortages, economic development, warfare,
desertification
•Should we use more irrigation?? Cultivate more land???
Environmental Impacts of Food Production
•Biodiversity loss
–Loss and degradation of grasslands, forests, and wetlands
–Fish kills from pesticide runoff
–Killing wild predators to protect livestock
–Loss of genetic diversity of wild crop strains produced by monoculture strains
•Soil
–Erosion
–Loss of fertility
–Salinization
–Waterlogging
–Desertification
•Energy
–Uses about 17% of all commercial energy in the U.S. each year
–10 units of nonrenewable fossil fuel energy are needed to put 1 unit of food energy on the table => there is a large net
energy LOSS!
•Water
–Water waste
–Aquifer depletion
–Increased runoff, sediment pollution, and flooding from cleared land
–Pollution from pesticides and fertilizers
–Algal blooms and fish kills in lakes and rivers caused by fertilizers and agricultural waste
–“Dead” zones in the Gulf of Mexico from runoff in the Midwest
•Air pollution
–Greenhouse gas emissions from fossil fuel use (CO2)
–Greenhouse gas emissions from use of inorganic fertilizers (N2O)
–Greenhouse gas emissions of methane (CH4) by cattle (mostly belching)
–Other air pollutants from fossil fuel use and pesticide sprays
•Human Health
–Nitrates in drinking water (blue baby)
–Pesticide residues in drinking water, food, and air
–Contamination of drinking and swimming water from livestock wastes
–Bacterial contamination of meat
Improve Food Production
Shift to more sustainable agriculture: organic agriculture?
Don’t use synthetic fertilizers, synthetic pesticides, genetically modified seeds, no feed additives, growth
hormones, etc.
Buy locally grown food
Decreases transportation costs and reduces greenhouse emissions