1. Environmental Science Chapter 15 Review
Arable land – able to grow crops
Soil formation –involves bedrock decomposition
Topsoil – upper layer of soil
- rock particles, water, air, organic matter
Yield – amount of a crop per hectare (acre)
Soil erosion (fields) – caused by farm machinery
Desertified farmland
-domestic animals overgraze the land
-too many crops are grown/looses fertility
-as a result of erosion

2. Environmental Science Chapter 15 Review
Irrigation water usually comes from rivers & groundwater.
Salinization – accumulation of salts in the soil caused by irrigation & low rainfall
Using rainwater instead of groundwater on crops reduces soil salinization.
Using strips of vegetation in between plowed land reduces soil loss caused by wind & water.

3. Environmental Science Chapter 15 Review
No-till farming – seeds planted among roots of previous crop.
Livestock – cattle, goats, pigs, sheep, chickens
Ruminants – cud-chewing mammals
Wheat requires less energy than cattle or cows.
Modern Agricultural methods use plowing machines, drip irrigation systems, and chemical fertilizers.

4. Environmental Science Chapter 15 Review
DDT harmful to environment
-does not break down easily in environment
-causes some birds to lay thin shelled eggs
-concentrates in animal bodies
(persistent pesticides)
Pest
- organism that occurs where it is not wanted
- can become resistant to pesticides

5. Environmental Science Chapter 15 Review
Integrated pest management – chemical, biological & farming methods
Food production has not been increasing as fast as the human population – many go hungry
Famine – widespread food shortage
Malnutrition – health problem due to not eating necessary nutrients

6. Environmental Science Chapter 15 Review
Humans need 8 essential amino acids from the proteins they eat.
Carbohydrates supply energy for the body.
Lipids (fats & oils) help form membranes/hormones.

7. Environmental Science Chapter 15 Review
Aquaculture
- raising of aquatic organisms for human use
– reduce seafood overharvesting
No fishing zones – reduce effects of overharvesting
Genetic Engineering – desirable traits transferred

8. Environmental Science Chapter 15 Review
Living organisms maintain soil fertility
-fungi, bacteria, microorganisms decompose dead plants/animals/excrement
-certain bacteria convert atmospheric nitrogen into forms plants can use.
-earthworms, insects, small animals break up soil, letting in water/air.

9. Environmental Science Chapter 15 Review
Reducing water erosion of farmland
-mixing in stems, roots from previous crops
-loosens topsoil so water soaks in/not run off
-worms attracted to this organic material
-aerate topsoil so water soaks in/not run off
-contour plowing stops water running downhill

10. Environmental Science Chapter 15 Review
Biological insecticides (bacteria, reproductive-interfering agents) - target pests but do not harm others.
Chemical insecticides can persist or build up and then harm other species which feed on the insects.

11. Environmental Science Chapter 15 Review
Erosion in farming
only recently a serious problem (modern machinery & practices)
previous farmers did not leave bare soil exposed in huge fields
small fields & gardens = less runoff
practiced crop rotation
fields allowed to lie fallow every few seasons

12. Environmental Science Chapter 15 Review
Explain how pests develop a resistance to pesticides.
Word bank = aquaculture, famine, genetic engineering, livestock, malnutrition, meat, overharvesting, pest, ruminants, salinization, topsoil, yield.