Chapter 4: Soil Water Properties

Question 1

Molecules like little magnets, have generally “+” and “-“ charged sides.

Answer 1

Polar

Question 2

Molecules stick slightly to each other

Answer 2

Cohesion

Question 3

Molecules stick to other charged molecules.

Answer 3

Adhesion

Question 4

Forces holding or moving water in the soil.

Answer 4

Soil Water Potential

Question 5

Water held to soil particles by hydrogen bonds.

Answer 5

Matric Potential

Question 6

Water held to dissolved salts in soil solution.

Answer 6

Solute Potential

Question 7

Gravity “pulling” water through the soil.

Answer 7

Gravitational Potential

Question 8

Water that drains “freely” from soil, usually about 3 days after irrigation.

Answer 8

Gravitational Water

Question 9

Amount of water (usually inches per foot of soil) held by soil after gravitational water drains off.

Answer 9

Field Capacity

Question 10

Amount of water held in soil when plants are permanently damaged from water stress.

Answer 10

Permanent Wilting Point

Question 11

Amount of water held in soil between field capacity and permanent wilting point.

Answer 11

Available Water Capacity

Question 12

Many soils in __________ County are affected by salt.

Answer 12

Kern

Question 13

The more negative the charge, the ____________ the bond.

Answer 13

Stronger

Question 14

Clay is a “sponge” because of ____________.

Answer 14

Oxygen

Question 15

Solute Potential is generally a ________ thing.

Answer 15

Bad

Question 16

Solute Potential is very important to _________________.

Answer 16

Agriculture

Question 17

All ________ __________ have a lot of oxygen radicals sticking out.

Answer 17

Living Things

Question 18

Most crops can remove __________ of the water (on average).

Answer 18

Half

Question 19

Soil is __________ charged, so it sticks to water.

Answer 19

Negative

Question 20

Water is ____________ charged.

Answer 20

Positive

Question 21

High heat Capacity can ___________ crop production.

Answer 21

Extend

Question 22

Ice has a lot of _______ in it that insulates and protects lakes and other bodies of water.

Answer 22

Air

Question 23

Hydrogen parts of water __________ to soil.

Answer 23

Attach

Question 24

Sand has _______ negative charge.

Answer 24

Low

Question 25

Silt has a higher ____________ charge.

Answer 25

Negative

Question 26

Clay has a ________ negative charge.

Answer 26

High

Question 27

Field Capacity in an “average” AG soil = ______ Water of saturated soil.

Answer 27

1/2

Question 28

Available Water Capacity in an “average” AG soil = _____ field capacity.

Answer 28

1/2

Question 29

__________ ___________ have low field capacities, but may have moderate available Water holding capacity, because all water that is left after drainage is available.

Answer 29

Sandy soils

Question 30

__________ have highest field capacity, but low available water capacity, because waster held very tightly to clay particles.

Answer 30

Clays

Question 31

Best all around soil is the _________ soils with high field capacity and high available Water Capacity.

Answer 31

Loamy

Question 32

Weigh, dry, weigh again

• slow, labor intensive
• Good for lab samples that must be dried anyway

Answer 32

Gravimetric

Question 33

Air pressure pushes water out of soil

• Pressure needed related to water content
• Good for quick results in lab

Answer 33

Pressure Bomb

Question 34

2 electrodes, 1 cm apart, inside porous block. Conductivity related to water content of block; more water = more conductance.

• Blocks can be buried in soil
• Relatively cheap and fast and reliable
• Inaccurate in salty soils

Answer 34

Porous Blocks

Question 35

Method where you will squeeze the soils with your hand to see if water drips from it or if it forms a ball. You can also roll the soil and see if it falls apart.

Answer 35

Soil feel method

Question 36

Device put down hole that emits fast neutrons. Neutrons that hit water are reflected, returned and are measured.

• Proportion of slow to fast related to water content
• Immediate results and 100% accurate
• radioactive
• you need to be licensed to do this method

Answer 36

Neutron Probe

Question 37

Water reflects radio waves (radar), much more that soil particles

• Proportion of received to emitted waves estimates soil water
• Very expensive equipment
• Certain wave frequencies will penetrate the soil, and the frequency coming back will indicate the water content.

Answer 37

Radio Waves

Question 38

Tubes filled with water with a porous cup on the end. As water pulled out into dry soil from cup, water level in tube drops and measured by suction on meter

• Relatively cheap
• Not very accurate in dry soils

Answer 38

Tensiometers

Question 39

Moves by the force of gravity

• Before the three days are over
• Starts with infiltration and can end with deep percolation

Answer 39

“Free” or Saturated Flow

Question 40

___________ textured soils have much more saturated flow than ___________ textured soils.

Answer 40

Coarser; Finer

Question 41

_________ _________ increases saturated flow by keeping soil pores open.

Answer 41

Organic Matter

Question 42

Flow in soil pores from field capacity to permanent wilting point

Answer 42

Unsaturated Flow

Question 43

Unsaturated flow will flow from wetter to drier areas and can flow against gravity to bring up _________.

Answer 43

Salts