topic 5: soil Flashcards
functions of soil
- plant growth, supplies plants with nutrients and water and a place to grow
- water storage
- provides a habitat for living species and organisms that modify soil
- soil modifies the atmosphere through respiration of plant roots and soil organisms
sphere name of soil
pedosphere
factors affecting soil characteristics
- climate
- organisms
- relief
- parent material
- time
factors affecting soil characteristics
climate
- precipitation evaporation balance, direction of water movement
- wetter/drier soil
factors affecting soil characteristics
organisms
- break down the dead organic matter and mix it into the upper layers of soil
factors affecting soil characteristics
relief
- elevation, direction and angle of the slope
factors affecting soil characteristics
parent material
- organic material the soil develops from, bedrock or drift deposit
factors affecting soil characteristics
time
- development of soil, how much time it’s developed for
- non renewable natural capital
soil ecosystem
biotic
micro-organisms
- bacteria, algae, fungi
macro-organisms
-earthworms, insectes, millipedes, moles
soil inputs
- minerals, weathering of parent material
- organic matter, living organisms on or in the soil
- gasses, plants that fix atmospheric nitrogen into nitrates in the soil, organisms in the soil also respire removing oxygen and adding carbon dioxide
- water, slope and where the slope is, top of the slop receives the most water
soil stores
- organic matter, dead organic matter
- organisms, adding nutrients when they deposit waste and break down DOM
- minerals, parent material form the body of soil, may be used by some plants
- gasses, store of gasses dependent on weather conditions and number of organisms and plant roots, different soil textures different air spaces
- water, dependent on weather and soil texture
- nutrients, stored in organic matter but also free in soil
soil outputs
- loose minerals, organic matter, wate and gasses through wind
- plants take nutrients and carbon dioxide from the soil for growth, plants are moved nutrients are lost
soil processes, transfers and transformations
leeching and evaporation
- water moving down the soil layers and dissolve soluble materials
- areas of high evaporation water moves upwards, high temp moves the water up, salts are left behind (salinization)
soil processes, transfers and transformations
decomposition
- fungi, algae and bacteria
- transformation of organic matter to nutrients increases soil fertility
soil processes, transfers and transformations
weathering
- breakdown of parent material adding minerals to soil
- dependent on climate and type of rock
soil profile top to bottom
- o
- a
- b
- c
o horizon
organic layer, humus
- top layer of soil
- includes all DOM that accumulates on top of the soil
- DOM becomes humus which mixes into soil over time
a horizon
topsoil
minerals, humus
- second top soil, mineral layer
- dark in color, high organic matter
- highest biological
- often absent in clay
b horizon
subsoil, minerals
- sub soil zone of accumulation
- minerals and particles washed into this horizon by ones above (illuviation)
- plant roots likely but very little humus
c horizon
parent rock, partially weathered
- decomposed parent material
- not really impacted by soil processes
- large lumps of parent material
soil texture
- proportions of sand, silt and clay
- result of parent material and type of weathering
sandy particle properties
- gritty
- large particles and space between them
- well drained, rarely water logged
- subject to drought
- warm up fast in summer
clay particle properties
- sticky
- smallest particles small space
- poorly drained, prone to water logging
- long time to dry out
- warm up slowly
silt particle properties
- smooth
- too small for the human eye
- texture in between clay and sand
soil nutrient retention
- finer soils tend to store more nutrients
- ideal mix of sand silt and clay (loam) for agriculture
Norman Borlaug
- 1940s green revolution
- change in agricultural productivity
- synthetic fertilizers, pesticides, mechanization and other technological developments
- increased food yield
low income countries food security
- low food security
- intense methods of food production
- increased environmental problems
- fertilizers and pesticides, pollution of aquatic systems
- irrigation can lead to soil salinization
- high crop production, soil nutrient deficiency and soil degradation
factors influncing type of farming
- environmental conditions, suitable for certain plants or animals
- access to technology and vehicles
- available funds to purchase land and inputs
- cultural and EVS
- government and political initiatives
intensive commercial farms use
- GMOs for higher yields
- fertilizers to encourage max growth
- herbicides to kill weeds
- insecticides
- water
- mechanical equipment
- automated technologies
- more frequent sowing to increase the number of harvests
environmental impacts of intensive commercial farms
- pesticides can kill non target organisms reducing overall biodiversity, some can bioaccumulate and magnify growing up concentrations in food chain
- fertilizers, nutrient run off, eutrophication
- uses limited water sources for agriculture
- monoculture increases risk of disease, impacts all crops
- mechanical equipment, non renewable fossil fuels and ghgs
- excessive irrigation, soil degradation, nutrient run off, salination
- loss of natural habitats, loss of biodiversity
- loss of pollinators such as bees due to pesticides
concerns of intensive animal farming
- rapid spread of disease
- ethical concern
- growth hormones, health problems in humans, animal waste into the environment
- antibiotic use, disease resistant
- high concentration of organic waste matter, pollute water systems
organic farming techniques
- physical removal of pests or weeds
- introduction of native biological predators
- manure and compost for fertilizer
- crop rotation, different crops grown each year, maintain soil fertility, reduce buildup of soil pests
- livestock fed without routine use of drugs and growth hormones, space to move
consumers that drive organic farming
- greater health concerns
- ethical concerns
- increased awareness of production methods
- increased income and standard of living
subsistence farming systems
- nomadic livestock herding, shifting cultivation
- meeting the demands of family or community
shifting agriculture
- slash and burn
- farmed until loss of all soil fertility
- farms another area and the burnt one grows back
- low human population can be a sustainable system
- not effective for high populations
nomadic herding
- moving animals to search for suitable grazing areas
- often traditional to africa
- low inputs and outputs
intensive subsistence farming
- produce enough food to feed their families, slight surplus to sell
- traditional labour intensive
reasons for hunger
- poverty. cant afford
- poor infrastructure, limited access and distribution
- extreme weather events
- war and displacement of people
- food waste, estimated 1/3 food produced lost/wasted each year
food waste
- pests
- loss during preparation
- inadequate/ unreliable transport
- perishable, poor storage
- damaged, inappropriate size, misshapen
- consumer behaviour
- best before/display by date
- excess food purchased
ways to reduce food waste
- changing individual behaviour, raising awareness of food waste
- encouraging collaboration between different steps in the food supply chain, identify problems
- farmers matching demand
- improvements to transportation and preservation, packaging
