Soils

Soils

1. How is it formed?

   • Weathering
     • Types:
       • Chemical
       • Physical
     • breaking down of rocks into smaller ones
   • Erosion
     • Carried away from the bigger parent rocks
     • Agents
       • Most common
         • Water
         • Wind
       • Not that common
         • Ice
     • How to prevent/reduce it?
       • Methods
         • Terracing
           • consists in doing level in high places so water do not take all the nutrients while falling
         • Bunds
           • artificial banks for waater so in that way soil not become waterlogged
         • Contour ploughing
           • hold water and prevent large torrents of water
         • Windbreaks
           • Trees or a wall that slow down wind and so do not take all content
         • Crop rotation
           • consist in leaving a space between crops, so after a few years you must change the distribution of crops and so in that way there is a place you will be keeping the nutrients for some years. If not, crops are always using the same nutrients
         • Adding organic matter
           • add organic matter such as animal manure helps soil with nutrients
   • Characteristics
     • Took thousands of years

2. Characteristics

   • Depeding on the size of the weather rock, it can be consider:
     • Clay
       • Characteristics
         • The smallest
         • Poor drainage/ High permeability
           • Retain a lot of water
         • Roots have difficulty growing
         • White or light- coulored.
         • Nutrient rich
         • Compacts easily
         • Heavier than sandy soil
     • Sand
       • Characteristics
         • High drainage/ low permeability
           • Don't retain water
         • The biggest
         • Roots grow faster
         • Mostly brownish
         • Semiarid zones
         • Poor fertility
         • Acidic
         • Low organic matter
     • Silt
       • Characteristics
         • Bigger than clay, smaller than sand
         • Features of both extremes but in lesser degrees.
           • Good drainage
             • Retain water
         • Beige to black
   • Depending on if it is clay, silt or sand, particle sand has different properties
     • The soil texture pyramid
       • • LOAM
           • The Best for farming
     • Every combination has different propierties
   • form layers over bedrock
     • Horizons
       • They are 5
         • 0 horizon
           • organic
           • dead plant matter
             • Detritus
         • A horizon
           • Real soil surface
           • The BioMantle
             • Most soil organisms reside
         • B horizon
           • Subsurface
           • Farthest plants go
         • C horizon
           • Large rocks and soil between
           • Bedrock degrades into soil
         • R horizon
           • rocks
           • Roots will go for soil
     • Took thousands of years
   • order
     • 1. order
     • 2. suborder
     • 3. great groups
     • 4. family
     • 5. series
   • latitude & humidity aren't the only features to take into account where different orders of soil are found

3. Orders

   • Entisol
     • Characteristics
       • No development of the soil horizons
       • very young
       • Most usual type of soil
   • Inceptisol
     • Characteristics
       • More horizon development
       • Begins in B horizon
   • Gelisol
     • Characteristics
       • Permafrost close to surface
         • consecuently, horizons are underdevelop
       • High latitudes in Artic and mountain renges
         • Northern Russia and Canada
   • Spodosol
     • Characteristics
       • close to equator
         • Scandinavia & Canadian East Coast
       • low fertility
         • decomposing into acidic compounds
       • Acid
         • due to pines
           • Coniferous & boreal forests
   • Aridisol
     • Characteristics
       • little to no water
         • Soil erosion
       • sand, silt & gravel
       • Sahara, Arabia, Australia, Northern China & western USA
   • Ultiosol
     • Characteristics
       • Red because of iron
       • Subtropical & humid places
         • American South East & Southest East Asia
   • Alfisol
     • Characteristics
       • Horizon development
       • Rich in iron & aluminium
   • Mollisol
     • Characteristics
       • Most fertile
         • Best for agriculture
         • American Midwest & The Pampas region of South America.
         • Grassland soils
   • Oxisol
     • Characteristics
       • Low nutrient availability
         • Low fertility
       • Horizons more develop, but hard to see
       • Rain forests, Amazons & The Congo.
   • Andisol
     • Characteristics
       • recently volcanic soil ejected from a volcano
       • Rich in nutrients
       • Hawaii & Japan
   • Histosol
     • Characteristics
       • wetland soils
       • Highly acidic
         • Unstable for structures
       • Contain peat and other organic matter
       • Undergraded organic matter
         • impermeable layer
       • Canada & River Deltas
   • Vertisoil
     • Characteristics
       • High clay content
       • Dry out regularly
         • soil cracked
           • soil invert layers, because soil entered into the cracked spaces.
       • India, Sudan
   • CLORPT
     • CL: climate
     • O: organisms
     • R: relief
     • P: parent material
     • T: time

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