test #2

Question 1

pores

Answer 1

air pockets in soil

Question 2

soil structure

Answer 2

how soil particles stick together to form peds

categorized by: type & grade

Question 3

structureless soil peds

Answer 3

Massive and single grain (sand/sand-sized)

extremes in terms of effects on permeability

neither present great conditions for crop use

Question 4

Structure grade

Answer 4

determines soil quality

says how strongly the ped is held together

four grades: strong, moderate, weak, structureless

Question 5

good structure=

Answer 5

good aeration because of more pore space

Question 6

organic matter

Answer 6

important for forming soil structure

Question 7

effective depth

Answer 7

soil evaluation criteria relative to structure

is the zone which plant roots can easily grow (the deeper the effective depth the better)

Question 8

limitations of effective depth/barriers for root growth are caused by

Answer 8

massive soils, dense soil structure, poor internal drainage, abrupt texture changes between horizons, gravely and large sands

Question 9

components of soil

Answer 9

45% minerals, 5% organic matter, 50% air and water

Question 10

soil particles

Answer 10

sand silt clay

Question 11

sand

Answer 11

.05-2mm, round shape, gritty, adds porosity, reduces water holding capacity

Question 12

silt

Answer 12

.002-.05mm, round shape, smooth, not sticky, moderate porosity, helps water holding capacity

Question 13

clay

Answer 13

less than .002mm, flat or platy, sticky, bad for porosity,(fit together tightly because they are so small), locks in water/makes it unavailable for plants use

Question 14

relationships of soil and water/soil quality

Answer 14

defined by two principals:
permeability
water holding capacity

Question 15

permeaility

Answer 15

the rate which water moves though soil

depends on texture, structure, organic matter (porosity)

Question 16

porosity

Answer 16

pores in the soil are created by: roots and other organic matter (i.e. decaying substances)
animals (worms and rodents)
soil particle size and ‘fit’

Question 17

rapid permeability rate

Answer 17

texture: sands and silts
structure: strong/well defined
porosity: porous

Question 18

slow permeability rate

Answer 18

texture: clays
structure: weak and massive
porosity: not porous

Question 19

water holding capacity

Answer 19

the quantity of water retained by soil particles

depends mainly on texture
improved by organic matter

Question 20

high water holding capacity

Answer 20

texture: silts, loams and clays

organic matter: present

Question 21

low water holding capacity

Answer 21

texture: sands

organic matter: absent

Question 22

soil water

Answer 22

available water

unavailable water

saturated soils

Question 23

available water

Answer 23

free for plants use

Question 24

unavilable water

Answer 24

held too tightly by clay particles

Question 25

saturated soil

Answer 25

have exces water that will run off increasing erosion concerns