Please enable JavaScript.

Coggle requires JavaScript to display documents.

Soil Aeration (Importance/Composition (Factors (Microbial and root…

- - - - Produced by nitrification and denitrification
      - 310 x more potent than CO2
    - - Produced by methanogenesis and consumed by methane oxidation
      - 21 x more potent than CO2
  - - - Occurs due to waterlogging
      - Pores filled with water
    - - Denitrification - conversion of nitrate to nitrogen gas - results in loss of fertiliser
      - Greenhouse gas (methane, nitrous oxide) production
- - - - Soil type
      - Crop type
- - - - In soils, volume remains constant, if temperature increases, then pressure increases
      - Gases move from high to low pressure down gradient
      - Diurnal variation
        
        Soil heats in day, gases expand, pressure increases, air moves out of soil
        
        Soil cools at night, air moves in
        
        Similar in seasonal variation
    - - If atmospheric pressure changes, then affects gas movement
    - - Air blowing across surface sucks air out of soil pores
      - Mainly affects pores near surface
    - - Following drainage, evaporation
    - - By rainfall, irrigation etc.
  - - - Diffusive flux qd is proportional to concentration gradient (dc/dx)
      - qd =-Dg dc/dx
      - Dg = diffusion coefficient
        
        Dg varies with each gas, temperature, pressure, medium through which the gas moves
        
        Approx 10^4 x faster in air than water - saturated soils can't supply enough O2 or remove CO2 quickly enough for some plant to grow well
- - - - Texture - εa decreases with increasing clay content - lowest in clay soils, highest in sands
      - Structure (macropores and aggregates important) - responds to management
      - Water Content - dependent on rainfall
      - Depth - bulk density increases with depth, so porosity decreases with depth
    - - Varies with plant - usually 5-20%
      - Often 10% used
        
        Below which some plants are adversely affected
        
        Some plants require saturated conditions - some wetland plants pump oxygen into their rhizosphere