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Summary OCR A Level Geography Future of food 4.a
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Covid 19, pandemic, supply chains
In areas such as north Africa the number of women landowners is
less than 5%, leaving women more vulnerable to food insecurity
violence and even extreme weather events caused by climate
change
4.a Imbalance in the global food system has physical and human
impacts
Over time, attempts have been made to increase food production and
therefore ensure food security in order to cater to a growing population.
This has had numerous impacts on our physical environment due to the
intensification of farming
Achieved through:
Higher yields per unit of land
Crop intensification
Increased land being farmed
Mechanisation
Impacts on soil
Erosion by wind and water, compaction by machinery and livestock,
decline in OM, salinisation, desertification (due to overgrazing and
overcultivation), leaching (downward movement of nutrients so they
are out of reach for plants)
KEY EXAMPLE: Sahel
Impacts on biodiversity
Decreased biodiversity due to land clearance, deforestation
(fragmentation, degradation, destruction)
KEY EXAMPLES: Indonesia palm oil, Amazon soy
Landscape
Hedgerow control, wetland drainage, terracing of slopes, increasing
field size, monoculture, built environment of farming
Water
Depletion of water sources (e.g. Kenya- green bean production,
exacerbated by land grabbing, Murray- Darling River basin e.g.
between 2002 and 2009 experienced worst drought in 125 years
due to El Niño- had to import food (food price), degraded soil, wider
spread impact on ecosystem), pollution by agrochemicals, silting of
streams (soil into rivers)
, Irrigation and salinisation
A result of:
1. Over irrigation
2. Over abstraction of ground water, especially in coastal areas due to
the infiltration of marine, saline water into fresh groundwater
3. Coast sea water intrusion e.g. Tuvalu
Salinisation is a type of soil and land degradation that is a result of the
build-up of salts in soil
Where is it common?
Arid and semi-arid regions- areas at risk of desertification are often also at
risk of salinisation
How much of the world is affected by salinisation? Future projections?
20% of cultivated land worldwide is affected by high salinity
Salinised areas are increasing at a rate of 10% annually, so by 2050 50%
of arable land would be salinized
What climactic factors cause salinisation?
High rates of evaporation and transpiration (hot areas) combined with low
precipitation and poor soil drainage
Describe how salinisation occurs
1. Significant evaporation of water leaves salt behind
2. Consequently, capillary rise draws saline groundwater to the surface
to replace this lost water- result of H bonds between water
molecules that give them a cohesive nature
3. This saline groundwater evaporates and leaves behind salt and
minerals on the surface e.g. chloride, sulphate and carbonate
A duricrust forms in extreme cases which means that water cannot
infiltrate at all into the soil. This does not have the nutrients for crop
growth
What is the consequence of salinisation?
Plants cannot uptake water due to the reduced water potential of the soil
due to an increased concentration of solute i.e. salt, so water has more of
a tendency to diffuse by osmosis down the water potential gradient out of
the plant into the soil rather than the other way round
Case Study example:
1 Timbaki basin in Crete, Greece
Intense agriculture and tourism
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