Chapter 9&10 Flashcards
How did the Green Revolution help food production?
The Green Revolution increased production through breeding, fertilizer, and irrigation.
Productivity of global agriculture increased drastically as a result of new advances. During this
time period, new chemical fertilizers and synthetic herbicides and pesticides were created. High-
yield crops were also developed and introduced..
What are GMOs and what are the pros and cons?
Removes DNA from one organism and splices it into the chromosomes of another. Produces
genetically modified organisms (GMOs) with new traits
● Pros: Can produce crops with pest-resistance and wider tolerance levels to fr ost, drought, low nutrient and salty soils. Can improve protein or vitamin content of crop. Can incorporate oral vaccines into foods such as bananas for use in developing nations. Animals can be modified to grow faster or produce pharmaceuticals in their milk.
● Cons: Opponents worry that: GMOs might produce superweeds resistant to pesticides. Native biodiversity may be reduced. Novel toxins might be created. Technology may only be available to the rich, making family farms uncompetitive and driving poor nations further into poverty.
Define soil
Soil is a renewable resource that develops gradually through the weathering of rocks and the accumulation of organic material.
How long does it take to replace 1mm of top soil?
1 year
In general soil has 6 components. Please list them:
● Sand and Gravel ● Silts and Clay ● Dead Organic Material ● Soil Fauna and Flower ● Water ● Air
Define soil texture and loam
- Soil Texture: (the amount of sand, silt and clay in the soil)
- Loam: Loam soils are considered best for agriculture because they are a mixture of sand, silt and clay.
What is a soil profile? What are the correct order of the Layers(horizons) and what is the composition of each horizon?
Soils are stratified into horizontal layers called soil horizons. Horizons taken together make up the soil profile
●O Horizon (Organic layer): Leaf litter, most soil organisms and partially decomposed organisms
●A Horizon (Surface soil): Mineral particles mixed with organic material
●E Horizon (washed out): Depleted of soluble nutrients
●B Horizon (Subsoil) (Often dense texture due to clays
●C Horizon (Weathered rock fragments with little organic material )
What is reduced tillage and how it helps the soil?
Reduced tillage or conservation tillage is a practice of minimizing soil disturbance and allowing crop residue or stubble to remain on the ground instead of being thrown away or incorporated into the soil.
- Define desertification. Intensive farming leads to soil erosion. List 5 means by which the soil erosion due to intensive farming occurs.
Desertification: Conversion of productive land to desert
5 Soil erosion causes due to intensive farming:
- Row crops leave soil exposed
- Weed-free fields
- Removal of windbreaks
- No crop-rotation or resting periods for fields
- Continued mono culture cropping can increase soil loss tenfold
What is salinization? How can use of fertilizer be harmful?
- Salinization - mineral salts accumulate in soils; lethal to plants
- Overuse of fertilization causes water pollution.
What type of pesticides has the greatest use in the modern agricultural production?
Organophosphates – most abundantly used synthetic pesticides.
● Roundup is the most commonly used organophosphate herbicide
● Genetically modified Roundup resistant crops have been produced
● Other organophosphates are used as insecticides and inhibit cholinesterase, an enzyme necessary for nervous system function.
● Quickly degrade and do not persist.
● Dangerous to workers and can be lethal
What are examples of use of pesticides in ancient times?
- The ancient Sumerians used sulfur to kill insects and mites over 5000 years ago.
- The ancient Chinese used mercury and arsenic to control pests.
- Greeks and Romans used oil, sulfur, ash, lime and other natural materials to protect their livestock and crops from pests.
What are the pros and cons of modern pesticides?
● Pros: inexpensive, stable, easily applied, highly effective.
Cons:
1. Unintended consequences on non-target species.
- Broadly sprayed pesticides might not reach intended target and instead kill beneficial organisms.
- A few resistant pests survive the pesticide and survive to repopulate the area with more resistant pests.
- WHO estimates 25 million people suffer pesticide poisoning, and 20,000 die each year.
Give examples of organophosphate, chlorinated hydrocarbon and fumigants, inorganic pesticides and how they work. Are they persistent ?
● Organophosphate: Pesticides like Roundup. Quickly degrade, do not persist.
● Chlorinated Hydrocarbon: Atrazine, DDT.. and concentrate in food chains. Persistent.
● Fumigants: Small molecules (e.g., carbon tetrachloride) which are delivered as a gas to penetrate soil or other materials. Used in fungus control on strawberries or to prevent insect/rodent damage to stored grains
● Inorganic Pesticides: compounds of toxic elements such as mercury or arsenic. Highly toxic, indestructible and persistent. Generally act as nerve toxins. Persistent.
How do natural pesticides and biological control agent work on pests?
- Natural Pesticides: Pesticides-generally extracted from plants and include such pesticides as nicotine or pyrethrums. Toxic to insects and may prevent wood decay
- Biological Control Agents: living organisms or toxins derived from them that are used in place of pesticides. Parasitic wasps such as Trichogramma kill moth caterpillars and eggs. Ladybugs are used to control aphids
