Soil Flashcards
Soil purposes
supplies water/stores carbon/habitat
formation of soil
weathering of rock (mechanical/biological/chemical)
machinery on soil
compresses soil and compact air which is needed for organisms and remove tunnels for worms
organic matter
carbon, organisms, 90% wetlands, 1% desert
layers of soil
A horizon/top soil (organisms live/nutrients), B horizon/subsoil (materials from above and below), C horizon/parent rock (rock breaks down
porosity
size of pores, clay has small, sand has large
why arent small/large spaces ideal for farm soil
too small means water doesnt move, too large means water moves to fast
surface area/nutrients
large surface means more nutrients hold onto soil, clay holds better nutrients
rhizosphere
soil in contact with roots, nutrients
what soil is good for farming
loam (mix of clay/silt/sand)
animals in soil
nematodes (graze on bacteria), fungi (decomposition), bacteria (nitrogen uptake)
degradation
when soil loses physical/chemical/biological properties due to overgrazing/construction
soil erosion
loss of topsoil by wind/poor management
protect soil for future
policies to prevent soil degradation
main nutrients
nitrogen/phosphorus/potassium
macro nutrients
small amounts (all 3 main)
micro nutrients
need in large amounts (iron)
soil fertility
ability to support plant growth, soil increases fertility by cation exchange
sandy soil nutrients
nutrients sink to bottom so too far to reach plants
clay soil nutrients
usually clay bonds ionic attraction to nutrients so arent available for plants unless unattached so root hairs pump protons out which bind to nutrients and bind to clay
how plants uptake nutrients
ions dissolved in water travel by active transport by special proteins
pH
affects binding of ions/nutrient absorption
organic fertilisers
manure, slow release
inorganic fertiliser
artifical nitrogen, immediate uptake
