5.1 introduction to soil systems Flashcards
soil is dynamic
- rocks weather, soil increases
- wind blows, soil decreases
- water washes away nutrients, DOM puts them back
- plants take nutrients then die and decompose, returning nutrients
- plants absorb carbon dioxide and emit oxygen, animals reverse
soil is a mixture of
- minerals
- organic matter
- air
- water
functions of soil
- medium for plant growth, nutrients, water, place to anchor
- water storage and purification system
- habitat, bacteria, insects and mammals
- modifies the atmosphere, respiration of soil organisms and plant roots
pedosphere
- soil
lithosphere
- rocks
hydrosphere
- water
atmosphere
- ari
biosphere
- living
factors impacting soil characteristics
climate
- precipitation/evaporation balance
factors impacting soil characteristics
organisms
- break down DOM and mix it into the upper layers of soil
factors impacting soil characteristics
relief
- elevation of the land, aspect and angle of the slope
factors impacting soil characteristics
parent material
- original material soil developed from
- bedrock, drift deposit
factors impacting soil characteristics
time
- development of soil, non renewable natural capital
biotic component of soil
- organic debris broken down by decomposers in the top layer of soil, bacteria, small insects
- earthwords breakdown DOM into humus
- nitrogen fixing bacteria, symbiotic relationship with legume plants
soil
inputs
- minerals
weathering of parent material from physical, chemical and biological processes - organic matter
from living organisms on and in the soil
succession, early plants dying adding organic material - gases
nitrogen fixation, atmospheric nitrogen into nitrates and ammonia
respiration - water
direct precipitation, flow
soil
stores
- organic matter
biotic elements, anything that lived - organisms
add nutrients when they deposit waste, break down DOM - minerals
parent material - air
gases in the soil, different soil types different air spaces - water
- nutrients
stored in organic matter or free in the soil
soil
outputs
- wind, physically removes soil
- water, washes away minerals
- plants harvested or removed from the area, nutrients lost
soil
processes, transfers and transformations
gas exchange
- respiration, photosynthesis, nitrogen fixation, evaporation
P/E balance determines
- the dominant direction of water movement in soil
- precipitation down
- evaporation up
- hot and dry = high evaporation rates
- brings mineral salts to the surface, water evaporates salts are left, salinization
- wet and cold = high precipitation rates
- water washes soluble minerales out of soil, leeching
decomposition
- break down DOM to release plant nutrients
- gradually increases soil fertility
weathering
- breakdown of parent material
- adds minerals to the soil
soil horizons
o
- organic horizon
- on top of the soil, includes DOM
a
- top soil/ mineral layer
- high proportion of organic matter
- highest biological activity
b
- sub soil
- zone of illuviation/accumulation
- minerals and particles washed in from ones above
- plant roots
c
- decomposed parent material, larger clumps`
soil types
sand
- large particles
- well drained, rarely water logged
- subject to drought
- warms up quickly due to high air content
soil types
clay
- smallest particles
- poorly drained, prone to waterlogging
- long time to dry after rainfall
- warm up slowly due to high water content
