Agriculture: Part 2

Increasing food production

© Brooks/Cole Publishing Company / ITP

Green Revolutions: increasing crop yields

per unit areaFirst Green Revolution• Developed countries 1950s-

1970s• Increased the intensity and

frequency of cropping• Widespread mechanization• Used large amounts of

fertilizers, pesticides, and water

Second Green Revolution• Started in the late 1960s• Spread industrialized farming

to developing nations• Selective breeding and later

genetic engineering led to faster growing varieties of rice and wheat that could thrive in tropical climates

Fig. 15–3

•1st Green Revolution in 1950s-1970s

•2nd Green Revolution after 1967

© Brooks/Cole Publishing Company / ITP

Green Revolution

•increase and change inputs of water, fertilizer, & pesticides

-eventually these additions produce no additional increase in crop yields.

© Brooks/Cole Publishing Company / ITP

Increasing Crop Yields

•breeding (artificial selection)

•genetic engineering-increase proportion of photosynthesis going to food;

-develop strains of plants that are resistant to disease, cold, pests, toxins, insects, & drought.

- Ex. Corn, cotton, soybeans, Ex. Corn, cotton, soybeans, canola, squash, and papaya.canola, squash, and papaya.

© Brooks/Cole Publishing Company / ITP

The Gene Revolution: Increasing Crop Yields

Mixing Genes• Genetic engineering involves

splicing a gene from one species and transplanting the DNA into another species.

Advantages:•Need less fertilizers, water, pesticides•Less spoilage and damage•Tolerate higher levels of herbicides•Higher yields per acre

Disadvantages:•Unpredictable genetic & ecological effects•New allergens or toxins in food•Lower genetic diversity•Can harm beneficial insects

Golden Rice• Golden rice is a new

genetically engineered strain of rice containing beta-carotene.

• Can inexpensively supply vitamin A to malnourished and prevent childhood blindness.

• But…

Figure 13-1Figure 13-1

Increasing meat production

• From 1950-2000 meat production increased from 52 billion kg to 240 billion kg

• More and more countries are moving towards a “Western” diet

• 70% of corn harvest in US goes to animal feed

• 80% of world soybean harvest goes to animal feed

• Further increasing meat production would put a strain on world grain resources and world fisheries (1/3 of catch is used for animal and farm fish feed)

What will this mean for land use?

How will meat production keep up with demand?

Animal Feedlots

Advantages Disadvantages

Increased meat production

Need large inputs of grain, fish meal, water, and fossil fuelsHigher profits

Concentrate animal wastes that can pollute water

Less land use

Reduced overgrazing

Reduced soil erosion

Antibiotics can increase genetic resistance to microbes in humans

Factory farming will likely expand

Aquaculture: Aquatic Feedlots• Raising large numbers of fish and

shellfish in ponds and cages is world’s fastest growing type of food production.

• Fish farming involves cultivating fish in a controlled environment and harvesting them in captivity.– Fish on fish farms must be fed 5 pounds

of wild-caught fish to produce one pound of farmed fish flesh (Robbins 2004)

• Fish ranching involves holding anadromous species that live part of their lives in freshwater and part in saltwater.– Fish are held for the first few years,

released, and then harvested when they return to spawn.

© NOAA