Soil The basis of the living skin of the planet
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- Slide 1
- Soil The basis of the living skin of the planet.
- Slide 2
- Four components Air Water Minerals Organic matter
Traditionally, they are seen as : Air, Water, Earth and Fire (as
Biomass represents the capture of solar energy)
- Slide 3
- Air Atmospheric gasses, present in spaces created by
interstices of soil particles Atmospheric gasses, conducted into
passages and pores created by macroorganisms Atmospheric gasses,
transported into the soil through the action of vegetation.
Atmospheric gasses, transported into the soil through the action of
extra fossorial events
- Slide 4
- Water 1. Water is gained by the soil through rainfall or flood.
2. Water is lost by the soil through gravitational action,
transpiration and evapotranspiration 3. Microorganisms and plants
influence the retention of water in the soil 4. The capacity to
retain water influences the biodiversity of the soil ecosystem and
vice versa 5. Water composition of the soil is impacted by
compression or disturbance. 6. The water composition of the soil is
greatly influenced by short-term climate events
- Slide 5
- Earth Earth is represented by minerals that constitute the
non-organic solid component of soils. This mineral fraction of soil
is described in terms of the size of particulate matter. Ranging
from rock, sand to clay. Minerals are usually transported by wind,
water or other geologic agency or are found in situ where they were
formed. The mineral fraction of soil usually takes many thousands
of years to form
- Slide 6
- Fire Solar energy that sequesters organic matter Geothermal
energy that sequesters organic matter Nuclear energy that
sequesters organic matter.
- Slide 7
- Organic Matter Truly the Cinderella. The wonder of the world of
soil carbon has generally been ignored by much of soil science.
Ranging from about.01 to 10 % in proportion. This diminutive
fraction is really the engine that drives all of agriculture. The
principal property of soil fertility is determined by biological
factors, mainly by microoganisms. The development of life in the
soil endows it with the property of fertility.Krasilnikov
1958.
- Slide 8
- Soil Biodiversity One gram of soil may contain 1-2 billion
individual bacterial cells. This accounts for a mass of about
350-7100 kg of bacteria per hectare in the upper 15 cm of soil.
Similarly it has been found that actinomycetes may reach
populations of 200 million or more individuals per gram of soil.
This group which falls between the bacteria and fungi are able to
decompose organic matter at moisture levels too low for either
bacteria or fungi to operate effectively. The fungi are present in
similar numbers and often have a kilometre of hyphae in a gram of
soil (Allison, 1973).
- Slide 9
- The combined biomass of all soil organisms in one hectare is
equal to that of twenty horses The daily operation of these
organisms yield the power of about 20 HP per hectare. This energy
goes into maintaining the productivity and sustainability of the
soil ecosystem.
- Slide 10
- As this component is reduced, the biological power component to
sustaining the soil is reduced. The process if allowed to continue
leads to desertification and complete loss of soil
productivity.
- Slide 11
- Regenerating soils How can we design an active soil ecosystem
that is analagous to the mature soils that once existed in the area
? The living soil should be supported by a terrestrial ecosystem
that provides it with the critical OM increment What is missing in
terms of mineral matter and biodiversity should be replaced
exogenously but in a seral sequence, that is analogous to the
native systems.
- Slide 12
- Techniques in regenerating soils Ramial chopped wood
Remineralization Revegetation MSI Mulching Composting
- Slide 13
- Roots and Soil Tree Roots provide up to 20% of their total root
weight as exudates into the surrounding soil. Each Species of tree
provides differing chemical compounds Many species of trees have
distinct species of associated soil organisms
- Slide 14
- Water is a critical part of soil
- Slide 15
- The thermal regime of soils is determined by the vegetation
cover and OM content of soils Absorption of solar radiation
Chernozerms86% Gray soils80% White soils20%