Physical Factors That Affect Food Security Flashcards
Geology
Soil - what is it
Mixture of mineral and organic matter in which crops grow
Length of the growing season and temperature
each crop requires a minimum threshold of temperature and a growing season of a specific length for sufficient growth
Eg, UK most cereal crops require a temp of 6 degrees at a minimum
Cotton requires a growing season of 200 days
Some varieties of wheat = 90 days
In the tropics = temp high for a year long growing season ( providing there is adequate precipitation)
Increased latitude and altitude reduce the length of the growing season
How do the physical factors set spatial limits for crops to grow
Crops require specific climatic and soil conditions
Determines the length if the growing season
Despite technical advances - the ability to produce sufficient food is significantly influenced by the physical environment
Soil - what influences farming
Depth, drainage, texture, structure, Ph and mineral content of soils
Soil - what are important characteristics from a Agri point of view
Texture - size of mineral particles determine the soils ability to store nutrients and hold moisture
Coarse - textured = leached and acidic
Structure - the way soil particles are bound together to form soil aggregates which allow air,water and plant roots to penetrate the soil
Nutrient supply - soils supply plants with the chemical elements for growth ( particularly nitrogen, phosphorus and potassium)
Partially decomposed organic matter increases the nutrient supply
Natural ecosystems = nutrients are recycled
Agro- ecosystems = harvesting removes nutrients
Precipitation and water supply
Annual precipitation determines the growth cereals, grass and root crops to grow
The effectiveness in terms of evapotranspiration and seasonal distribution are important.
Coffee = dry period before harvesting
Maize = high levels of rain to ripen
Precarious balance between precipitation and food production
Eg, India relies on its monsoon rains, if they are late or fail the impact on food security is severe
Prolonged rainfall of moderate intensity = infiltration
Heavy downpours = rapid run-off and moisture will not reach the root zone of crops
Altitude and aspect
Shows the link between climate, soils and the growing season
Height increases = temperature decreases = snow and precipitation increase = growing season decreases
Therefore, nutrient cycling is slower and leaching is present
Aspect - impacts the microclimate
NH - South - facing slopes receive more light and therefore are warmer and have drier soils and faster evapotranspiration rates and crops grow at higher altitudes ( vice versa with north-facing slopes)
Relief
Angle impacts erosion rates and the use of machinery
Impacts soil depth and drainage = affects the type of crops that can be grown
Steep slopes = thin soils, poorly developed and excessively drained
Soil at the base = waterlogged
Gentle slopes = less movement of water through the soil which results in less erosion and leaching
How can we mitigate the problems with the physical environment?
Modern technology
Eg, infrared tech in Kenya
Famine early warming systems in Sahel (FEWS)
SOIL TYPES
Clay - heavy and acidic with a high levels of organic matter with retention rate can lead to water logging - poor drainage therefore require dykes and drainage ditches
Sandy - well drained and less acidic - leaching of nutrients sometimes too well drained, prone to drought and therefore requires fertiliser added to replace and irrigation
Loam - mixture of sand, silt and clay with little erosion - best for agriculture with a 20/ 40 mix
