Soil systems

Question 1

what is soil

Answer 1

made up of minerals, organic material, gases and liquid

Question 2

what does soil do

Answer 2

• plants grow in soil
• soil is habitat for many organisms
• soils hold water and mineral nutrients
• soils store and transfer heat

Question 3

soil consists of

Answer 3

• rock particles
• plant and matter in process of decomposition
• water
• air
• soil organisms

Question 4

soil horizons (layers)

Answer 4

O horizon - newly added organic material

A horizon - where humus builds up and is mixed up with fine material particles

B horizon - where soluble minerals and organic matter is deposited

C horizon - mainly weathered rock

Question 5

sandy soils

Answer 5

gritty and fall apart easilty

Question 6

silty soils

Answer 6

slippery when wet and hold together

Question 7

clay soil

Answer 7

feels sticky and can be rolled into ball easily

Question 8

loam soil

Answer 8

• good for agriculture
• sand particles ensure good drainage
• clay retains water
• silt particles help hold sand and clay particles together

Question 9

subsistence farming

Answer 9

• the provision of food by farmers for their own families or local community
• low inputs of energy in the form of fossil fuels or chemicals
• vulnerable to food shortages

Question 10

commercial farming

Answer 10

• large profit making scale
• high levels of technology, energy and chemical input
• uses more land with a lower density of crops

Question 11

pastoral farming

Answer 11

• raising animals on land not suitable for crops
• uses large amounts of land

Question 12

arable farming

Answer 12

• growing crops on good soils
• primarily to eat or feed animals

Question 13

malnutrition

Answer 13

raising animals on land not suitable for crops

Question 14

factors affecting food choices

Answer 14

• climate - determines what grows where on earth
• political - governments can put subsidies or put tariffs on food
• social and economic - market forces determine supply and demand

Question 15

terrestrial food systems

Answer 15

• food is usually harvested at first and second trophic level
• therefore production systems make efficient use of solar energy
• have higher losses coming to skeletal waste

Question 16

aquatic food systems

Answer 16

• food comes from higher trophic levels
• energy efficieny is lower than terrestrial
• energy losses in heat are higher

Question 17

how to increase sustainability of food supplies

Answer 17

improving technology - mixed cropping, buffer zones, pest control

altering what we grow - gm food doesnt need pesticides, soil conservation, reduce food waste

Question 18

prediction for future food supplies

Answer 18

• human population will grow to 8 billion by 2030
• calorie consumption increasing to 3000kcal per person
• numbers of hungry people will decrease to 400 million
• GM crops increase productivity

Question 19

processes that lead to degradation

Answer 19

• overgrazing
• deforestation
• unsustainable agriculture`

Question 20

overgrazing

Answer 20

• when too many animals graze in the same area
• leaves bare patches of soil which are removed by wind and rain
• takes many years for region to recover

Question 21

overcropping

Answer 21

• depletes soil nutrients
• reduces soil fertility
• crops more prone to failure

Question 22

deforestation

Answer 22

• removal of forest
• the more vegetation removed, the more prone to erosion

Question 23

soil cultivation techniques

Answer 23

• cover crops between rows of main crops keeps soil in place
• plowing breaks up soil structure and increases drainage
• contour farming plows along cultivation lines, reducing erosion