physical properties

Question 1

function of soil in an ecosystem

Answer 1

physical environment for plat to root in (seed/soil contact important), provides water, aeration, nutrient source and heat.

Question 2

soil as a rooting medium

Answer 2

root space important - root is strong but it can’t make its own pores, porosity, pore continuity, soil material strength

Question 3

importance of pore size

Answer 3

more like im-pore-tant, pore size is key.
water sticks to pore surfaces, surface tension. allows for root travel, water holding, and airation

Question 4

physical properties of soil

Answer 4

texture, structure, shrink/swell potential, compressibility, frost susceptibility.
all of this is summed up into:
- particle density
- bulk density
- porosity

Question 5

soil texture meaning in a nutshell

Answer 5

relative proportion of mineral particles of a different size.
sand is coarse, silt is flower-like, and clay is sticky/paperlike

Question 6

sand particle size

Answer 6

2.0-0.05mm

Question 7

silt particle size

Answer 7

0.05-0.002mm

Question 8

clay particle size

Answer 8

<0.002mm

Question 9

development of soil texture

Answer 9

water/glaciation or wind, not management.

Question 10

significance of soil texture

Answer 10

volume and pore size - water movement, aeration, roots, and surface area

Question 11

how to determine soil texture

Answer 11

many methods, hydrometer (lab), pipette, or using stokes law

Question 12

stokes law

Answer 12

disperse soil in a salt water, measure time to sink a certain distance.
measure using the smallest diameter - bigger diameter would’ve already fallen by then.
V=Kr^2, t=h/Kr^2
K=34700cm/s

Question 13

pipette method

Answer 13

measure controlled amount of water, boil it down to determine weight difference and whatever at diff times

Question 14

hydrometer

Answer 14

idk, something w density

Question 15

particle size distribution curve

Answer 15

measure how much in suspension at a size, every soil type can still have diff curves.

Question 16

soil structure

Answer 16

arranging primary soil particles and organic matter to definable secondary structures like aggregates
for plants, need root/air/water space

Question 17

granular soil structure

Answer 17

enough small pores for seed-soil contact, and pores for roots and shoots

Question 18

how are soil structures formed?

Answer 18

drying/wetting, freezing/thawing, biological activity

Question 19

crop impact of freezing and thawing

Answer 19

perennial crops with tap root (really deep one) get impacted - freezing in the root splits it and pushes it up, causing winter kill. more snow insulates the ground better and reduces winter kill

Question 20

organic content on soil stability

Answer 20

good, great even, maybe. perhaps. very good for soil stability no cap

Question 21

characterization of soil structure

Answer 21

particle density, bulk density, volume fraction of pores (pore space ratio). basically pore size distribution and continuity

Question 22

bulk density

Answer 22

dry soil mass/volume of soil.
sand has most density, clay has least
think of it like water holding ability.
tillage can reduce BD, if only for a moment.

Question 23

particle density

Answer 23

soil solid mass (dried)/volume of solids
kinda a constant

Question 24

pore space ratio

Answer 24

1-bulk density/particle density
clay has the largest ratio, sand has smallest

Question 25

pore size

Answer 25

big - macro, small - micro, middle - meso varies w texture and structure, clay soils have ,ore mircopores than sands, sands have more macro than clays clay has smaller particles itself

Question 26

mirco pore significance

Answer 26

have strong capillary action, holds water on the surface, water is not plant available bc can't be sucked out

Question 27

meso pore significance

Answer 27

plant available water, variable porosity, where lil hairy roots can go

Question 28

Marco pore significance

Answer 28

not a lot of capillary action, drains out easily, keeps soil oxygenated, allows air flow. roots grow in large pores, can't create new pores

Question 29

compaction

Answer 29

increase in bulk density - loss of large pores. large pores go first and easiest, break into small ones. more water, less air/roots. sand not easily compacted, clay easily compacted. bc of pore space ratio

Question 30

tractor compaction

Answer 30

most at contact point, not as much impact further down. wider wheels decrease compaction

Question 31

shear

Answer 31

soil pushed around a load - not as much compaction as it looks

Question 32

higher BD on root structure

Answer 32

shorter, thicker roots, not as much water access

Question 33

lower BD on root structure

Answer 33

more drought hardy, long thing roots increase surface area and water intake

Question 34

erosion

Answer 34

small aggregates picked up and brought away. reduced by slowing water down, reducing a slope and slowing potential

Question 35

management practices to improve soil structure -

Answer 35

no