How Is Food Produced?

•Sources of food

•30,000 edible plant species

•90% of calories come from only 14 plant and 8 terrestrial animals.

•Primary plants:
wheat, corn, and rice (supply >50% of cal)

•Primary animals:
fish, beef, pork, and chicken

Major Types of Agriculture

•Industrialized agriculture


•Traditional subsistence agriculture

•Traditional intensive agriculture


World Food Production

Producing Food by Green-Revolution Techniques

•High-input monoculture

•Selectively bred or genetically-engineered crops

•High inputs of fertilizer

•Extensive use of pesticides

•High inputs of water

•Multiple cropping


Green Revolutions

Case Study: Industrialized Food Production in the United States

•The U.S. uses industrialized agriculture to produce about 17% of the world’s grain.

–Relies on cheap energy to run machinery, process food, produce commercial fertilizer and pesticides.

•About 10 units of nonrenewable fossil fuel energy are needed to put 1 unit of food energy on the table.

•How much fuel does it take to produce fuel (biofuels)? 

Case Study: Industrialized Food Production in the United States

•Industrialized agriculture uses about 17% of all commercial energy in the U.S. and food travels an average 2,400 kilometers from farm to plate.

Producing Food by Traditional Techniques

•Polyvarietal cultivation


•Agroforestry (alley cropping)



Traditional Agriculture: Low Input Polyculture

•Research has shown that, on average, low input polyculture produces higher yields than high-input monoculture.

Soil Erosion

•Soil erosion is the movement of soil components, especially surface litter and topsoil

•Caused by




Global Soil Erosion

•Soil is eroding faster than it is forming on more than one-third of the world’s cropland.

Soil Degradation on Irrigated Land




Reducing and Cleaning Up Salinization

•Reduce irrigation

•Switch to salt-tolerant crops

•Flush soils

•Not growing crops for 2-5 years

•Install underground drainage

Solutions:  Soil Conservation

Soil Restoration

•Organic fertilizers

–Animal manure

•Green manure


•Crop rotation

•Commercial inorganic fertilizer


World Food Production

•Now leveling off

•Shortages in developing countries


Environmental Effects of Food Production

•Biodiversity loss

•Soil degradation

•Air pollution

•Water shortages and erosion

•Human health


Producing More Meat




•Improved rangeland management

•Environmental consequences


Catching and Raising More Fish


•Fishing methods (See Fig. in text)


•Commercial extinction


•Fish farming and ranching


Government Agricultural Policy

•Artificially low prices


•Elimination of price controls

•Food aid


Pesticides:  Types

•Chemicals that kill undesirable organisms







First Generation Pesticides

•Primarily natural substances

•Sulfur, lead, arsenic, mercury

•Plant extracts:  nicotine, pyrethrum


Second Generation Pesticides

•Primarily synthetic organic compounds

•Broad-spectrum agents

•Narrow-spectrum agents

•Persistence in the environment


The Case for Pesticides

•Save human lives

•Increase food supplies and lower costs

•Work better and faster than alternatives

•Health risks may be insignificant compared to benefits

•Newer pesticides are becoming safer

•New pesticides are used at lower rates



Characteristics of an Ideal Pesticide

•Affects only target pests

•Harms no other species

•No genetic resistance

•Breaks down quickly in the environment

•Be more cost-effective than doing nothing


The Case Against Pesticides

•Genetic resistance

•The pesticide treadmill

•Can kill non-target and natural control species

•Can cause an increase in other pest species

•Pesticides do not stay put

•Can harm wildlife

•Potential human health threats



Bioaccumulation and Biomagnification

•Persistent (non-biodegradable) toxins build up in an animal over time = bioaccumulation

•Become more concentrated at higher trophic levels = biomagnification

Integrated Pest Management

•Ecological system approach

•Reduce pest populations to economic threshold

•Field monitoring of pest populations

•Use of biological agents

•Chemical pesticides are last resort


Why is Integrated Pest Management not More Widely Used?

•Requires expert knowledge

•Slower than conventional pesticides

•Initial costs may be high

•Hindered by government subsidies


Solutions:  Sustainable Agriculture

•Low-input agriculture

•Organic farming


•Increasing funding for research in sustainable techniques




Sustainable Agriculture

•Results of 22 year study comparing organic and conventional farming.