Lecture #11 Salinity

Question 1

Major cations in soil

Answer 1

Na+, Ca+, Mg++, K+

Question 2

Major Anions in soil

Answer 2

Cl-, SO4-, HCO3-, CO3-, NO3-

Question 3

Where does surface salt come from

Answer 3

fertilizer
rain with pollution
irrigation
sea water

Question 4

How does soil salinity affect osmotic potential?

Answer 4

Increased osmotic potential affects transpiration

decreased transpiration affects gaseous exchange

Question 5

How is salinity measured

Answer 5

Electrical conductivity (EC) of the saturation extract of pore water

Question 6

How is EC and salt concentration related?

Answer 6

Salt concentration = 640 x ECe

Question 7

How is EC related to osmotic pressure?

Answer 7

Osmotic pressure = 40 x EC at 25 celsius

Question 8

ECe effects

Answer 8

0-2 dS/m - nelgible
2-4 = slight effect
4-8 = significant effect
8-16 = only salt tolerant crops can grow
>16 = only high resistant plants survive