Soil Formation Flashcards
(23 cards)
How do soils form?
Rocks are broken into small fragments by weathering processes. OM is incorporated by the decomposition of plants and animals. These components are reorganised by aggregation and movement to form layers or horizons over time
What are the components of soil?
Minerals (45%) water (25%) air (25%) OM (5%)
What do plants need to survive?
Nutrients, water, air for respiration, support for roots, space for roots to explore soil, leaves need sunlight and CO2
What are igneous rocks?
Formed from molten Lava, not changed appreciably since they were formed
What are some examples of igneous rocks?
Granite, obsidian, pumice and basalt
What are sedimentary rocks?
Formed by weathering processes and formed in layers
What are some examples of sedimentary rocks?
Limestone, sandstone and shale
What are metamorphic rocks?
Formed either from igneous or sedimentary rocks which have changed due to excess heat and pressure
What are some examples of metamorphic rocks?
Marble from limestone
What affects soil formation?
Parent rock, climate, temperature, rainfall, time,flora,fauna and microorganisms, relief, altitude and slope
How does parent rock affect soil formation?
Determines colour, chemical properties, mineral content and permeability
How does climate, temperature and rainfall affect soil formation?
Influences rate of weathering and formation of humus
How does time affect soil formation?
Determines the thickness of a soil profile
How does flora,fauna and microorganisms affect soil formation?
Affects the rate of humus formation
How does relief, altitude and slope affect soil formation?
Determines accumulation of soil
What is physical weathering?
Heating and cooling, freezing and thawing, wetting and drying, abrasion, water, wind and changes to temperature
What is biological weathering?
Biological agents like plants and animals
What is chemical weathering?
Chemical means which cause permanent chemical changes ( solution, hydration and oxidation)
What is soil?
The growing medium for plants and roots, giving them water, mineral nutrients, oxygen and support
How can soil be damaged?
Pollution, compaction, erosion, sold off as topsoil
What is soil OM?
A mixture of plant and animal remains, excreta and living organisms
What are soil organism examples?
Earthworms, moles, slugs, beetles, bacteria and fungi
