Definitions Flashcards Preview

PLS 366 > Definitions > Flashcards

Flashcards in Definitions Deck (60):
1

topsoil

organically enriched, majority of plant roots found here

2

subsoil

where most water is stored, roots can't really grow here, it's hard to modify subsoil

3

disintegration caused by temperature, water, wind, ice, and organisms.

physical weathering

4

> 0.08 mm diameter, earthworms and small organisms can move through, water can move through

macropores

5

< 0.08 mm diameter, hold water so tightly plants can't access it

micropores

6

the hydrogen don't attach to the water evenly, they make a v-shape instead and this causes the positive charges to cling towards the side weighed down with the two hydrogens therefore causing this property of water

polarity

7

one of the hydrogens makes a low-energy bond to an oxygen particle from another molecule of water. this causes water to have a higher boiling point, specific heat, and viscosity

hydrogen bonding

8

the attraction of water molecules for each other

cohesion

9

the attraction of water molecules for solid surfaces, causes some water molecules to be held rigidly at the surface of soil solids

adhesion

10

results from the greater attraction of water molecules for each other than for the air above, causes an inward force at the surface

surface tension

11

force caused by adhesion, reduced the energy state of water near particle surfaces

Matric

12

force caused by cohesion, reduces energy state of water in the soil solution

osmotic

13

force pulling the water downward

gravimetric

14

process by which water enters the soil pore spaces and becomes soil water, takes place at the soil surface

infiltration

15

process by which water moves downwards into the soil profile, rate is related to the soil's hydraulic conductivity

percolation

16

when water addition stops the largest pores will drain downward rapidly, when this flow becomes negligible the soil is holding the maximal amount of water useful to plants

field capacity

17

all soil pores are filled with water, matric potential is close to zero, the soil will remain here only so long as water continues to infiltrate

maximum retentive capacity

18

the rate of plant water removal fails to keep up with the plant needs so the plant wilts

wilting coefficient

19

soil moisture is lowered below the wilting point, the water molecules that remain are very tightly held, most are absorbed by colloidal soil surfaces the water is held so rigidly that most of it can only move in the vapor phase

hygroscopic coefficient

20

an area of land drained by a single system of streams and bounded by ridges that separate it from adjacent watersheds

watershed

21

how water is returned to the atmosphere

Evaporation

22

after plant use it is vaporized from the stomata on the surfaces of the plant leaves

transporation

23

precipitation is intercepted by plant foliage and returned to the atmosphere by evaporation without ever touching soil

interception`

24

the physical condition of the soil in relation to plant grown

tilth

25

Name three primary properties used to delineate soil horizons

color, texture, structure

26

soil solids approximate this percentage of a loam at field capacity

50%

27

ions freely available for absorption by plant roots are found in this fraction

soil solution fraction

28

essential to plant respiration at interface of pedosphere and atmosphere

O2

29

degradation of OM from plant residues is considered this type of soil profile developmental process

transformation

30

limestone PM weathers into this bivalent cation which is an example of what kind of weathering

chemical Ca2+

31

name the five soil forming factors

time, biota, parent material, topography, climate

32

soils with equal amounts of each texture would be in which textural class

clay loam

33

most weathered soil order

oxisol

34

example of a clay mineral with extensive isomorphous substitution

smectite

35

a 1:1 silicate clay mineral

kaolinite

36

pH dependent charge, edge charges

kaolinite

37

vertisols are dominated by what types of charges

permanent charge

38

oxisols are dominated by what type of charge

pH dependent charge

39

clay with largest surface area

smectite, 2:1 w/ interlayer

40

what makes the water stay up in the fine textured stuff

matric potential (surface)

41

how does water move?

wet to dry, high to low potential, and macropores to micropores

42

highest capillary rise ultimately?

clay

43

smallest radius means

greatest height

44

how do you interpret the trends in ksat data with soil depth

it decreases with depth because there is higher clay that slows water movement because it's mostly micropores that just hold the water

45

range in soil water potential that defines the water available to plant roots

wilting point and field capacity

46

soil structure most prevalent in a C horizon

massive

47

soil structure most prevalent in a B horizon

blocky

48

soil structure most prevalent in a E horizon

platy

49

this soil separate is .05 to .002 and not gritty

silt

50

way to increase soil temperature

plastic and organic mulches

51

three factors responsible for soil aeration

soil macroporosity, soil water content, O2 consumption

52

when temperature rises, what happens to microbial activity?

doubles for ever 10 degree increase

53

next terminal electron acceptor when there is no longer any O2

NO3

54

Name the four soil forming processes

additions, losses, transformations, translocations

55

translocation

Movement of soil constituents (organic or mineral) within the profile and/or between horizons.

56

transformations

The chemical weathering of sand and formation of clay minerals, transformation of coarse OM into decay resistant organic compounds (humus)

57

losses

Through the movement of wind or water, or uptake by plants, soil particles (sand, silt, clay, and OM) or chemical compounds can be eroded, leached, or harvested from the soil, altering the chemical and physical makeup of the soil.

58

additions

Materials added to the soil, such as decomposing vegetation and organisms (organic matter--OM), or new mineral materials deposited by wind or water.

59

what is the charge of O?

-2

60

what is the charge of H?

+1