2.3) Biosphere

Question 1

• What are the summary of soil INPUTS?

Answer 1

• Soil inputs include:
  1. Water from atmosphere 💦
  2. Organic matter from decaying organisms 🦗
  3. Nutrients from weathered rocks ✨
  4. Excretions from plant roots 🫚
  5. Respiration from soil animals 💨
  6. Solar energy and gases from the atmosphere ☀️

Question 2

• What are summary of soil OUTPUTS?

Answer 2

• Soil outputs include:
  1. Evaporation 🌤️
  2. Water and nutrient loss by capillary action 💦
  3. Nutrients taken up by plants 🌱
  4. Nutrient loss due to water passing through the soil 🌧️
  5. Losses of soil material due to soil creep (downhill) 🏔️

Question 3

• What is the role of CLIMATE in soil formation?

Answer 3

• Climate is the long-term weather pattern in an area determined by:
  1. Precipitation 🌦️
  2. Temperature 🌡️
• Climate is the most important factor in the formation of soils. Soil produced from the same parent material under different climates contrast.
  ➞ When precipitation exceeds evaporation, leaching of the soil will occur.
  ➞ Temperature determines the rate of chemical and biological reactions. It influences the rate of decay of organic matter and weathering.

Question 4

• What is the role of ORGANIC MATTER in soil formation?

Answer 4

• Organisms in the soil influence soil development in a number of ways:
  1. Decomposers: Microorganisms carry out the decomposition of animal and plant material.
  2. Detritivores: Such as earthworms, aerate and mix the soil.
  3. Plants: Determine the nature of the humus and leaf litter. Roots bind soil paticles together.

Question 5

• What is the role of RELIEF in soil formation?

Answer 5

• Relief is a term used to describe the shape of the land, including the height and steepness.
• Relief influences:
  1. Soil thickness (as slope angle increases so does erosion) 🏔️
  2. Temperature 🌡️
  3. Runoff 💦
  4. Drainage 🌊
  5. Plant cover 🌱

Question 6

• What is the role of PARENT MATERIAL in soil formation?

Answer 6

• Parent material is the material from which the soil has developed (e.g., soild rock or clay).
• Parent material can influence:
  1. Colour 🟫
  2. Structure 🌱
  3. Texture ⌛
  4. Mineral composition ✨
  5. Permeability 🌧️

Question 7

• What is the role of TIME in soil formation?

Answer 7

• Soils develop very slowly.
• Young soils retain many characteristics of the parent material. Over time they acquire other features resulting from the addition of organic matter and activity of organisms.
• Soils pass through a number of stages as they develop, resulting in a deep profile with many well differentiated horizons (layers).

Question 8

• What is weathering?

Answer 8

• Weathering:
  ➞ is the exposure and breaking down or dissolving of rocks and minerals on the Earth’s surface due to interaction with the atmosphere.

Question 9

• What are the types of weathering (physical, chemical and biological)?

Answer 9

• PHYSICAL:
  ➞ weathering caused by changes in temperature, freeze-thaw, or effects of wind, rain and waves.
• CHEMICAL:
  ➞ where rainwater reacts with mineral grains in rocks to form new minerals (clay) and soluble salts (especially when rainwater is acidic).
• BIOLOGICAL:
  ➞ is a form of physical weathering caused by animals, plants, fungi and microorganisms.

Question 10

• What is humification?

Answer 10

• Humification:
  ➞ is the transformation of raw organic matter (e.g., leaves) into humus, where no recognisable plant parts remain.
• The process is carried out by detritivores.

Question 11

• What is decomposition?

Answer 11

• Decomposition:
  ➞ is the breaking down of organic materials into smaller constituent parts, especially by the action of decomposers.
  (e.g., the role of bacteria in the breakdown of organic proteins during the nitrogen cycle)

Question 12

• What is translocation?

Answer 12

• Translocation:
  ➞ is the movement of materials within the soil. There are several translocation processes:
  1. Leaching
  2. Eluviation
  3. Illuviation
  4. Capillary action

Question 13

• Describe the processes of translocation? (leaching, eluviation, illuviation, capillary action)

Answer 13

1. Leaching:
   ➞ is the movement of dissolved substances (e.g., nutrients) with percolating water in soil.
2. Eluviation:
   ➞ is the movement of suspended or dissolved compounds (e.g., salts) by percolating water from an upper into a lower horizon. The upper horizon is described as eluviated or E-horizon.
3. Illuviation:
   ➞ is the deposition of soil materials moved from the upper (eluviated) horizon to the lower (illuviated) horizon.
4. Capillary action:
   ➞ is the movement of water through pore spaces from wet areas to drier areas in soil. Often results in salts from groundwater being raised to the soil surface.

Question 14

• What are the biotic and abiotic factors that compose soil?

Answer 14

1. Mineral matter: from disintegration and decomposition of rocks.
2. Organic matter: from the decay of plant residues, animal remains and microbial tissues.
3. Water: from the atmosphere and reactions in the soil (chemical, physical and microbial).
4. Air or gases: from the atmosphere and from reactions of roots, microbes and chemicals in the soil.
5. Organisms: macro (worms, insects) and micro (bacteria).

Question 15

• What is particle size?

Answer 15

• The particles that make up soil are categorised into three groups by size - sand, silt and clay.
• Sand particles are the largest and clay particles are the smallest. Most soils are a combiantion of the three.
• The relative percentage of sand, silt and clay are what give soil its texture.

Question 16

• What is (soil) organic matter?

Answer 16

• Soil organic matter is the remains of dead plants, animals and microbes. It is usually dark brown or black in colour.
• In almost all mineral soils, there is some organic material called ‘soil organic matter’.
• The higher the organic matter, the greater the decomposition activity - and fertility - of the soil.

Question 17

• What are podzols?

Answer 17

• Podzol soils are associated with cool, wet climates where precipitation exceeds evaporation.
• They are found in Northern Boreal coniferous forests and upland moorlands. Parent material is glacial acidic rock.
• Annual precipitation is high and combined with snowmelt, this leads to very heavy leaching.

Question 18

• What are the HORIZONS of podzol soils?

Answer 18

• The Ao horizon forms from decaying plant material (including pine needles, cones and dead heather shoots).
• Organic matter decays slowly due to low bacterial activitiy due to low temperature.
• Lack of soil biota (organisms) prevents soil aeration and mixing. This leads to a clear line between A and B.
• Iron pan forms as a result of intense chemical leaching from iron ores.

Question 19

• What are the uses of podzol?

Answer 19

• Due to the extreme leaching, podzols tend to be non-productive, infertile soils.
• In Scotland, they are used for forestry (production of pine) or recreation (grouse moors).
• These soils are not suitable for agriculture due to high acidity.
  ➞ Lime (an alkali) would be required to neutralise the soil and high volumes of fertiliser would be required to replace nutrients lost through leaching.

Question 20

• What are brown earth soils?

Answer 20

• Brown earth soils are associated with a temperate climate where precipitation is greater than or equal to evaporation.
• They are found in temperate, deciduous woodland.
• The temperature allows intense biological activity (e.g., earthworms and bacteria).

Question 21

• What are the HORIZONS of brown earth soils?

Answer 21

• The Ao horizon forms from decaying deciduous leaves. This leaves a litter which is rich in nutrients.
• There are a large number of detritivores and decomposers, allowing a rapid rate of decomposition.
• The action of soil biota leaves indistinct horizons.
• Nutrients are well cycled through the soil system due to the long tree roots.

Question 22

• What are the uses of brown earth soils?

Answer 22

• Brown earth soils are used for agriculture as they are very fertile.
• However, to maintain soil fertility, farmers must add fertilisers to the soil.

Question 23

• What is biofuel?

Answer 23

• Biofuel is a diesel fuel derived from oils and fats in animals or plants (e.g., recycled cooking oil from restaurants)

Question 24

• What is bio-crude oil?

Answer 24

• Bio-crude oil is a biofuel obtained by heating dried biomass in an oxygen-free environment.

Question 25

• What is biomethanol?

Answer 25

• Biomethanol is a biofuel produced by gasification of biomass. This involves reactions using steam, intense pressure and limited oxygen .

Question 26

• What is bioethanol?

Answer 26

• Bioethanol is an alcohol made by fermentation of carbohydrates from plant materials. It can be mixed with petrol as a fuel for vehicles.