How do Food Production & security issues impact people & the physical environment?

Question 1

What is SALINISATION?

Answer 1

• a form of land degradation in arid and semi-arid climates
• the increase in the amounts of SALTS in the soil
• Salts appear naturally in soil , streams , rivers & groundwater

Brought to the surface when :
- High rate of evaporation & transpiration
- Low precipitation
- Poor soil drainage

• This salt layer is POISNOUS to plants and can INHIBIT water absorption

Question 2

Why does IRRIGATION cause salinisation?

Answer 2

Gravity flow methods of irrigation supply more water than crops can use , meaning :

• The excess water is evaporated in dry conditions
• CAPILLARY FORCE brings water to the surface of the soil & deposits salts

In COASTAL AREAS:
- Excessive withdrawal of underground water for irrigation
- causes the infiltration of saline water into fresh groundwater supplies

Question 3

Aral Sea ~ Asia

Answer 3

• Rise in food security pressures = heavy reliance on lake for irrigation of crops,
• Land irrigated with water used from the lake has LOST FERTILITY due to SALT BUILD-UP.
• VOLUME of the Aral Sea has fallen by 90%

Question 4

Land-management solution to salinisation

Answer 4

ALTERNATIVES TO OVER-IRRIGATION:
- drip feed irrigation ~ direct to root
- soil moisture monitoring
- accurate determination of water requirements

GOOD SOIL MANAGEMENT:
- maintain pH levels
- correct structure of soils

SALT-TOLERANT CROPS:
- sugar beet
- barley

MAXIMISE SOIL SURFACE COVER:
- use multiple crops with different growth habits
- maintain trees & shrubs to maintain water table