15-2 Crops and Soil Page 384

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.