15-2 Crops and Soil

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A. Fertile Soil: The Living Earth

• 1. Soil must be fertile to produce healthy plants.

A. Fertile Soil: The Living Earth

• 2. Topsoil, the surface layer of soil, is where plant roots grow.

A. Fertile Soil: The Living Earth

• 3. Soil primarily comes from the weathering of rocks.– Mechanical– Chemical

B. Soil Erosion: A Global Problem

• 1. Erosion is the movement of rock, soil, and sand by wind and water.

B. Soil Erosion: A Global Problem

• 2. U.S. topsoil has been eroded by 50% in the last 200 years.

B. Soil Erosion: A Global Problem

• 3. Farming increases the rate of erosion.

C. Land Degradation

• 1. Occurs when human processes or natural activity damage the land to the extent that the ecosystem can not be supported.

C. Land Degradation

• 2. Leads to desertification, where land in arid (lacking moisture) areas becomes even more desert like.

D. Soil Conservation• 1. To prevent down hill erosion:– Soil-retaining terraces– Contour plowing– No-till farming

E. Enriching the Soil

• 1. Through the use of manures and fertilizers.

E. Enriching the Soil

• 2. Compost uses partly decomposed organic material.

F. Salinization

• 1. accumulation of salts in the soil.

G. Pest Control

• 1. Pesticides are chemicals used to kill insects, weeds, and other crop pests.

G. Pest Control• 2. A negative is that pests can develop

resistance.

G. Pest Control

• 3. There are human health concerns such as cancer risks and nervous system disorders.

G. Pest Control

• 4. Persistent pesticides do not break down and accumulate in the soil and water.

H. Biological Pest Control

• 1. form of pest management that uses living organisms.

H. Biological Pest Control• 2. Pathogens, such as bacteria, may be used to

infect insect pests.

H. Biological Pest Control

• 3. Plant defenses are incorporated into plants, such as tomatoes, so that they are unaffected by certain fungi, worms, or viruses.

H. Biological Pest Control

• 4. Natural pesticides produced by plants that are biodegradable.

H. Biological Pest Control• 5. Disrupting insect breeding by use of

pheromones or chemicals that disrupt development. Ex: Fleas

I. Integrated Pest Management

• 1. uses a mixture of techniques to control pests and cause the least amount of economic damage.

J. Engineering a Better Crop

• 1. Genetic engineering is a technique in which genetic material in a living cell is modified for medical or industrial use.