Soil Flashcards
What essential functions does soil perform?
Reservoir for water (aquafiers etc), medium for plant growth and food, filters the air and the water, recycles dead plants/animals, storing huge amounts of carbon
Main components of soil
45% mineral. 25 % air. 25% water. 5% organic
Mineral part of soil
Formed by weathering of parent material.
Primary minerals = changed little since formation
secondary minerals = formed from breakdown and chemical weathering of less resistant primary minerals
Soil litter
remainder of decomposed animal and plant waste
Soil humus
A dark and organic material that forms in soil when plant and animal matter decays
Soil biomass
living organisms and plant roots
Mineralisation
The process where the breakdown of organic matter by microorganisms leads to nutrients being released such as nitrogen, carbon and phosphorus
Water in soil
Important as it is required for parent material weathering.
Saturated soil
When all the soil is saturated the pores are filled with water
Soil air
The air within the soil occupies the pore spaces within the soil (if it is not saturated with water that is)
Soil profile
Vertical section through the soil from ground surface down to the parent material.
Soil horizons
The layers within the soil profile.
O, A, E, B, C, R
O horizon
Basically the surface layer (soil humus). Consisting of organic matter (decay of animals and plants). Not always present.
A layer
The topsoil.
Contains rich organic material with minerals. High concentration of organic matter and microorganism.
E horizon
Elevation layer (may be missing in some soils) Mineral horizon. Lighter in color. Leaching happens here
B horizon
Mineral horizon but enriched in iron
Soil of acculumation.
C horizon
Loose material. Much of original material and fragments. often light in color.
R horizon
Bedrock. Form parent material.
Pedogenesis
Process of soil formation. The soil horizons develop after number of processes.
Processes like weathering, winds, rain etc.
A rock splits and expands leading to smaller particles entering the soil with new minerals.
Addition of pedogenesis
Comes from parent material. Can also be material gathered by wind or energy from the sun
Losses of pedogenesis
Removals from soil because of erosion or filtering
Mixing of pedogenesis
Mixing of organic and inorganic components is carried out by soil animals and plant roots or by freezing of water and shrinking/swelling.
Humans = ploughing
Factors affecting soil formation - Climate
Perhaps the most influential factor. Determines the moisture level and temperature and therefore amount of precipitation (affecting weathering).
Climate impacts weathering and the process of transforming the soil into different minerals (clay for instance)
Influences which productivity occurs of photosynthesis and therefore the amount of biomass integrated into the soil (A-horizon)
Little precipitation often leads to salinization and calcification
Factors affecting soil formation - topography
Altitude = can quickly change climatic conditions (usually drier and colder)
Higher slopes = allows for more erosion.
lower temp = less biological activity and less decomposition of organic matter
Dry podzol on top of steeper soil
Wet podzol further down
Lower topography often peat
Factors affecting soil formation - organisms/flora&fauna
Earthworms or other small animals mix and freshen the soil which creates pore spaces
Found to increase the infiltration rate
Could be animals, plants rooting or even humans ploughing that change biological factors such as moisture
Factors affecting soil formation - time
Time continually forms the parent material under the influence of the other factors.
Sedimentation and depositing takes time.
Important to be aware of the fact that soil processes are usually very slow and certain conditions are needed for changes to occur.
Impact of human activities on soil - erosion
further accelerated by human activities. Farming such as removal of vegetation and heavy machinery could affect. In turn this impacts our food supply chains.
Impact of human activities on soil - acidification
enhanced by use of fossil fuels resulting in acid rain and overuse of nitrogen fertilizers.
The more hydrogen ions the more acid the soil is.
Impact of human activities on soil - pesticides
Human use to protect crops. Have a broad spectrum activity.
Salinization and soil
Salt increase leading to less fertility.
Soil compaction
Caused by heavy machinery or trampling of livestock especially in wet soil conditions. Leads to reduced porosity of the soil and therefore increases risk of erosion as less water can infiltrate soils pores (less saturation can take place)
Terraced crop growing
Sustainable way to farm to avoid soil erosion with “steps” in slopes.
Definition of Land degradation
“Temporarily or permeant loss of productive capacity of land due to human action”
“A temporary or permanent decline in the productive capacity of the land. This can be seen through a loss of biomass, a loss of actual productivity or in potential productivity or loss or change in vegetative cover/soil nutrients”
Example of land degradation in Netherlands
Veluwe
Today mostly sand not forest
Peat has been dug out and animals used in deciduous forest, animals that eat ekthorns which leads to less nutrients and vegetation can therefore not grow
What are the main causes of land degradation?
Agriculture (drainage, deforestation and use of pesticides)
Extraction of recourses such as mining
Waste (drug waste in nature)
Urban growth
Different types of land degradation
Soil erosion, soil acidification, soil pollution, soil trampling, loss of organic matter, desertification, desiccation, salinization and loss of general biodiversity in soil
Soil erosion as type of land degradation
different processes contribute to erosion?
The weather, Vegetation cover, Land use, animal life, type of soil, water/precipitation and topography/steepness
Measures to help deal with erosion/land degradation
- contour ploughing (reduced overland flow)
- windbreaks (reduces wind power to erode)
- strip farming
- leaving crop remains on land
- winter crops
- terraces with slopes
What is pesticide and pest?
Pesticide = substance intended for preventing, destroying, repelling or mitigating any pest
pest = insects, mice, fungi, weed, bacteria or virus
Effects of use? Humans face the risk of direct exposure as well as drinking contaminated water and inhaling. Could lead to birth defects, kidney failure and cancer
Water balance and vegetation effects
Different scenarios depending on vegetation cover.
- Lot of vegetation. Means that each water droplet has less impact on soil. Trees can transpire the water
- No vegetation cover. Each water droplet has high impact on soil cover
- Urban buildings. No vegetation or sparse cover. Each droplet has high impact on overland flow.
What is soil? Definitions?
Non-renewable resource
Performs vital functions
Concerns the loose material and upper part of earths crust that is vital for vegetation
Transition between atmosphere, lithosphere, biosphere and hydrosphere
What are minerals in soil?
The solid materials (non pore space) = Gravel/stones are > 2 mm Sand 0.05-2 mm Silt 0.002-0.05 mm Clay < 2 nano mm
Soils tend to be a combination of minerals
Texture is result of weathering
Organic matter (5 % of soil composition)
Helps hold moisture and creates nutrients in soil
Water in soil
The amount of water depends on texture, structure and organic matter.
Example: lot of clay, means less pore space for water
Geogenesis
Builds up over time.
First step (before pedogenesis).
The stratification due to geological deposition
Process of pedogenesis: Transformation
Takes place when the soil freezes or calcium is broken down
Process of pedogenesis: Translocation
Particles in upper part of soil + moves within the soil
Soil formation factors: Parent material
Part of geogenesis
For example:
Fluvial (tend to be layered and well sorted)
Glacial (tend to be unlayered and not well sorted due to thick ice has pushed)
Lacustrine (lakes) (well sorted and layered with fine sediments)
Marine (sea) (layered and well sorted)
not clay marine (difficult to cultivate)
Organogenic (Low in minerals but layered) not always classified as soil
Soil across the world
The distribution of soil varies widely
Mountain soils, podzols, ice covered soils, arenosols, black clay soils, chernozem, laterite soils
Three categorises of soil
Zonal soils; characteristic for climatic zones
Intrazonal soils: independent of climatic variables
Azonal soils: young soils, cannot yet show clear signs of pedogenesis
Chernosem
Missing b horizon
High moisture (good for growing crops)
Russia
Brown earth soil
Deeper
good for agriculture
contains a lot of earth worms
Tundra
No layers in soil
Podzol
Clear layers
Red line in soil layer
Laterite soils
Experience huge precipitaiton
very productive and contains large amount of biomass
easily washed out by rain (organic material)
Netherlands soil
Clay (fertile and good for agriculture)
sand
peat
former dunes and beach soils (good for bulp growing in middle of netherlands)
Landscape triangular model
Landscape composed of three factors = Cultural (people), Abiotic (geology) and Biotic (nature)
Not about labelling. All factors are important. Some landscapes have stronger cultural functions while some stronger biotic functions.
UNESCOs world heritage can be both cultural and natural but only chooses one focus on each site.
Dutch landscape?
Around 20 different landscapes
People think of flat land. Reclaimed land and built environment. Farming. Man made and integrated. Canals. Tulips. Sand dunes.
“Dutch people have always batted against the water” - true or false?
Contextualising climate change - has corona changed something?
Not really. The fact that people want to use their own car and less public transport as well as working from home - rising energy consumption from servers.
KNMI had to adjust sea level rise to 1.2 - 2 meters
What do you need to know to study an impact?
Origin (path dependency could play a role - the past influences future development)
different depending on the region
Gyttja
sediment rich in organic matter deposited at the bottom of a eutrophic lake.
Bog peat VS fen peat
Fen peat = same level as regional ground water
Rich in nutrients
Results in lakes or strips of land
Rasied bog peat = above the regional ground water. Supplied by rain water and is poor in nutrients (oligotrophic)
Peat definition
The most widely distributed type of organic-rich
biological sediment is peat, which forms through the
accumulation of dead plant material in wet conditions
Leaching
Chemical removal of soil material by percolation of water
