salinity

salinity

high total concentration of SALTS in soil solution

sodicity

high concentraton of SODIUM IONS

plasmolysis

removal of water from plant cells resulting in their collapse

when do salts accuate at soil surface/common in whata regions

when evaporation is higher than internal drainage

elctrical conductivty

capacity of a substance to conduct ( transmit) electrical current

• measure of soil SALINITY

  • high EC = HIGH CONC of dissolved salts in soil solution

exchangable soidum percentage

degree to which exchagnge complex is saturated with sodium

• ratio of exhcnahgabe sodum relative to CEC

= (exhcnagable soidum/ CEC) x100

what is the worst case senario of salt affected soils

saline-sodic

• salt - pulls water out of plant cell = dessication

• sodium - prevents aggregate formation

influence of sodium for soil

thickness DDL = prevents aggregate formation

high conc outside= little differnce in concentration between ions in DDL and SS = ions less likely to move throuhg ther process of diffusion = ions in DDL dont move away and strech it

why would you want concentration of SS outside of DDL to be high

EC and ESP of saline soil

EC above 4

ESP less than 15

pH less than 8

EC and ESP of saline sodic soil

EC above 4

ESP above 15

pH7.5-8.5

EC and ESP of sodic soil

EC below 4

ESP above 15

and alkaline

impact of salt effected soils on crop production

• Decline in soil productivity and crop yields

  • kills plant - more salt in SS = low osmostic potential= water travels out of plant into SS

• Increased requirement and use of inputs including seeds, water and fertilizers

• Less choice in cropping systems, as farmers are forced to cultivate salt-tolerant crops, which might not be high income cash crops

• Reduced water use efficiency

Impacts of salt effected soils on living conditions of farmers and the economy

• reduction of yields results in less food supply, especially in subsistence farming

• Working with salt-affected soils requires more labour to reclaim soils

• The use of more inputs and the reduction of yields result in less returns, lower income for farmers

• Soil reclamation programs are costly

• reduced water quality

  • non floculated clays move through soil system and into groundwater and hydrosphere

salt effected soils, impact on ecosystems

• reduce diversity of soil organisms

• reduce eiffinciey of nut. cycling

• soil( left bare) more prone to other forms of degradation - erosion