13.2 Flashcards
what are the 3 important soil characteristics?
texture
structure
nutrient supply
- loam soil is best for agriculture
texture of soil
size of mineral particles in the soil
it determines the soils ability to store nutrients and hold moisture
coarse textured soils are often more leached and acidic
structure of soil
the way the soil particles are bound together to form soil aggregates which allow air water and plant roots to penetrate the soil
nutrient supply of soils
soils supply plants with the chemical elements needed for their growth
the most important being nitrogen, phosphorous and potassium
partly decomposed matter or humus increased nutrient supply
in natural ecosystems, nutrients are recycles, in agro-ecosystems, harvesting removes nutrients
temperature and growing impact on crops
each crop requires a minimum threshold temperature for growth
most UK cereals require a minimum temperature of 6 degrees
crops also need a growing season of a specific length eg cotton needs 200 days
increases in latitude and altitude, reducing length of growing season
precipitation and water supply impact on crops
average annual precipitation determines growth of cereals, grass and root crops or fruit and tree crops
amount of precipitation as well as effectiveness (evapotranspiration) and its seasonal distribution are important
some crops have specific requirements eg maize needs high levels of of precipitation to ripen
women countries are very dependent on rain eg India rely on annual monsoon
intensity and duration are also important
prolonged period of of moderate rainfall infiltrate soil
heavy downpours promote rapid run-off
moisture doesn’t reach roof
altitude impact on crops
demonstrates how climate, soils and growing season are interlinked
as height increases, temperature decreases and snow and precipitation increases and growing season decreases. Soil takes longer to develop. nutrient recycling is slower and leaching becomes more prevalent
aspect impact on crops
mountainous areas have steep slopes with different aspect which is important in determining micro-climate. In the northern hemisphere south facing slopes recieve more sunlight. South facing slopes are warmer and have drier soil. On South slopes, crops can grow at higher altitudes
evapotranspiration rates and temperatures are lower on north facing slopes
slope impact on crops
effects rates of erosion and use of machinery
impacts soil depth and drainage and crops that can be grown
on steep slopes, soils are thin, poorly developed and excessivley drained
soils at the base of the slope can become waterlogged
on gentler slopes there is less movement of water through the soil and a result less erosion and leaching
what is land grabbing?
acquisition of farmland in developing countries seeking to ensure their own food security
benefits of land grabbing to host country
creation of local employment
development of rural infrastructure
resourcing and introduction of new agricultural technology
creation of local food surpluses and enhanced food security
problems of land grabbing to host country
local farmers may be displaced with no prospect of alternative employment
creates unequal power relations between foreign national governments and local farmers who face growing food insecurity
define types of land ownership
owner occupies, tenants or landless labourers/employees on state owned or commercial land
land ownership in Russia
2001, Putin sought to address issue of land ownership
demand for private ownership of agricultural land has been low
in regions where farmers have purchases their own land
private farmers total 26,000 in Russia, but the vast majority of land remains under state ownership
land ownership in China
pre 1914, small intensive farms owned by an absentee landlords and work by tenant farmers
paid 1/2 of their produce to the landlord
post 1949 communist party appropriated farmland and redistributed it among peasant farmers
low output
commune system abolished and farmers can contract with the government to sell farmland rent free
