3.4 The soil system
3.4.1 - Outline how soil systems integrate aspects of living systems.
Soils are major components of the world's ecosystems. They form at the interface of the Earth's atmosphere, lithosphere (rocks), biosphere(living matter) and hydrosphere (water). Soils form the outermost layer of the Earth's surface, and comprise weathered bedrock(regolith), organic matter (both dead and alive), air and water.
The Soil interact with the atmosphere, lithosphere, biosphere and hydrosphere.
The Soil interact with the atmosphere, lithosphere, biosphere and hydrosphere.
- The water cycle moves through the soil by infiltration and water may evaporate from the surface
- The atmosphere may contain particulate matter that is deposited on the soils and praticles may blow up into the atmosphere
- Rocks in the lithosphere weather to form soils, and soils at depth and pressure may form rocks
- Plants in the biosphere may extract nutrients from the soils and dead plants may end up forming parts of the soil
3.4.2 - Compare and contrast the structure and properties of sand, clay and loam soils, including their effect on primary productivity.
Primary productivity of soil depends on:
- mineral content
- drainage
- water-holding capacity
- airspaces
- biota
- potential to hold organic materials
3.4.3 - Outline the processes and consequences of soil degradation.
Human activities such as overgrazing, deforestation, unsustainable agriculture and irrigation cause processes of degradation. These include soil erosion (loss of soil to wind and water), toxification and salinization (increase in salt concentration). Desertification (enlargement of deserts through human activities) can be a consequence with this degradation.
3.4.4 - Outline soil conservation measures.
- Soil conditioners (for example, use of lime and organic materials)
- wind reduction techniques (wind breaks, shelter belts, strip cultivation)
- Cultivation techniques (terracing, contour plowing)
- Efforts to stop plowing of marginal lands.
3.4.5 - Evaluate soil management strategies in a named commercial farming system and in a named subsistence farming system.
The North American Prairies and commercial farming
The problems occurred were increasing salinity, soil erosion and loss of soil fertility. Farmers managed to reduce salinity and erosion, to reduce salinity summer fallowing or leaving bare soil for long periods were stopped or reduced. Snow fences or barriers enabled snowdrifts to pile up which provide water then they melt in.
And to reduce erosion is used Contour ploughing- along the contour lines instead of up and down slopes traps soil and water. Strip Cropping – growing as flax and tall wheatgrass at right angles to the wind.
The problems occurred were increasing salinity, soil erosion and loss of soil fertility. Farmers managed to reduce salinity and erosion, to reduce salinity summer fallowing or leaving bare soil for long periods were stopped or reduced. Snow fences or barriers enabled snowdrifts to pile up which provide water then they melt in.
And to reduce erosion is used Contour ploughing- along the contour lines instead of up and down slopes traps soil and water. Strip Cropping – growing as flax and tall wheatgrass at right angles to the wind.