Lecture 9 soil water

Question 1

what is matric potential dependent on

Answer 1

pore geometry
por size distribution
particle aggregation
soil water content

Question 2

what can field capacity be dependent on

Answer 2

wetting history (can become hydrophobic)
soil type
OM content
depth of wetting 
plant uptake pattern

Question 3

definition of PMP

Answer 3

permanenet wilting point, water content of soil so low that even if ET =0 plants cant take up

Question 4

when can wilting occur

Answer 4

et rate exceeds uptake
no water
too salty for osmotic potential

Question 5

three ways to measure infiltration

Answer 5

ring infiltrometer
furrow infiltrometer
sprinkling infiltrometer

Question 6

whats the effect of rewetting on infiltration rates

Answer 6

infiltration rates drop when rewetting, because soil structure tightens before rewetting due to the negative pore pressures

Question 7

what are the four stages for the inflow hydrograph

Answer 7

advance stage (water getting to end of field)
soaking stage
depletion
recession (top of field goes dry)