Soils

1
Soils Soil Profile leaf litter topsoil
subsoil bedrock
2
Soils Soil Profile leaf litter decaying
organic material -mostly plant matter topsoil
a mix of minerals (sand, silt, clay) and and
thoroughly decomposed organic matter -lots of
available nutrients air spaces for plant
growth -retains water well due to organic
matter subsoil almost completely mineral
based -low in nutrients, tightly compacted,
poor water retention bedrock larger rocks
and solid rock beneath the layers of soil
3
Soils Mineral Composition of Soil Sand
largest soil particles (0.0625 1 mm) -provide
good drainage but poor water retention
Silt medium sized soil particles (0.004
0.0625 mm) Clay smallest soil particles
(less than 0.004 mm) -poor drainage but
better water retention -hard for roots to grow
through
4
Soils Soil Triangle a three sided graph used to
classify soil based on the composition of the
three soil particles
5
Soils Soil Triangle a three sided graph used to
classify soil based on the composition of the
three soil particles what type of soil
is 30 clay 60 silt
10 sand?
6
Soils Soil Triangle a three sided graph used to
classify soil based on the composition of the
three soil particles what type of soil
is 30 clay 60 silt
10 sand? silty clay
loam
7
Soils Soil Nutrients primarily nitrogen,
phosphorus potassium Natural Fertilizer plant
nutrients obtained from natural sources and have
not been chemically altered by
humans e.g. manure compost
8
Soils Soil Nutrients primarily nitrogen,
phosphorus potassium Natural Fertilizer plant
nutrients obtained from natural sources and have
not been chemically altered by
humans e.g. manure compost Synthetic
Fertilizer fertilizers that are manufactured
using chemical processes e.g. 777 pellet
style fertilizer from a garden centre
9
Soils Impacts of Fertilizer Application Depende
ncy synthetic fertilizers alter community of
soil organisms that produce natural
fertilizers -soil becomes dependent on continued
applications
10
Soils Impacts of Fertilizer Application Depende
ncy synthetic fertilizers alter community of
soil organisms that produce natural
fertilizers -soil becomes dependent on continued
applications Leaching nutrients flow out of
the soil as water passes through it -end up in
lakes causing algal blooms -algae eventually
dies and decomposing bacteria strip all the
oxygen out of the water -causes the rest of the
animals in the lake to die off
11
Soils Water Flow in Soils -farmers irrigate
land when precipitation is too low -farmers lay
tiling under fields to drain them when
precipitation is too high
12
Soils Water Flow in Soils -farmers irrigate
land when precipitation is too low -farmers lay
tiling under fields to drain them when
precipitation is too high Compaction loss of
air spaces when pressure squeezes soil particles
closer together air spaces provide -water
nutrients paths to reach roots oxygen for roots
and soil organisms