Food and Agriculture

Crops and SoilChapter 15Section Two

Agriculture: Modern vs. Traditional

• Machinery• Synthetic

fertilizers• Sprinkler systems• Drip irrigation• Pest management

• Manual labor• Organic fertilizers• Weeds removed

by hand• Relied on rainfall• Ditch irrigation

systems

Fertile Soil: The Living Earth

• Supports the growth of healthy plants• Topsoil – surface layer, rich in organic

matter• Subsoil – poorer in quality than

topsoil• Billions of organisms per hectare:

bacteria, insects, arthropods, earthworms, algae

Soil structure

Soil Erosion and Degradation

• Erosion – wearing away of rock and soil by wind and water

• Degradation – human activity or natural processes damage the land so it can no longer support the local ecosystem

• Desertification – land becomes more desertlike because of human activities

Soil Conservation

• Many ways to prevent downhill erosion

• Contour plowing – follow natural land contours

• Terracing – many small level fields• No-till farming – harvest and plant

next crop without plowing, reduces erosion to 1/10 of traditional methods

Enriching the Soil

• Traditionally – organic material such as manure & leaves which adds nutrients

• Modern methods include inorganic matter which can lead to runoff issues

• Best method – combination of both; compost, partly decomposed organic matter, combined with inorganic fertilizers

Salinization

• Accumulation of salts in the soil• California and Arizona – irrigation

water is saltier than rainwater and when it evaporates, salt is left behind

• Eventually, plants will not grow

Crops and Soil

Chapter 15Section Two

Part Two

Pest Control & Pesticides

• In NA, insects 13% of all crops• Worldwide, pests destroy 33% of

crops• Pest – any organism that is where it

isn’t wanted or in large enough numbers to cause economic damage

• Pesticides – chemicals used to kill weeds, insects & other crop pests

• Pesticides can kill/harm good plants, insects, wildlife, and people– Causes cancer in farmers,

manufacturing plant workers,

• Resistance – ability to survive exposure to certain pesticide

• Persistence – does not break down easily or quickly in the environment, build up in soil or water

• Some have been banned (DDT – made in US and sold overseas)

Biological Pest Control

• Use of living organisms to control pests

• Pathogens – cause disease in pests• Some plants have natural defenses

and come make defensive chemicals

• Disrupt pest breeding cycles

Integrated Pest Management – don’t eliminate the pest, just reduce the amount of damage

Engineering and Sustainability• Genetic engineering – modify genetic

material so plant can resist/kill pests– Bt corn

• Sustainable agriculture – conserve resources and keep land productive

• Low-input farming – plant pest resistant crops that minimize use of water, energy, pesticides & fertilizer

Genetically Modified Crops