SOIL SCIENCE

• Ion exchange is a reversible process by which ions are exchanged between solid and liquid phases and between solid phases if in close contact with each other
• Ion exchange occurs due to the presence of electrical charges in the soil
• Cation exchange is the attraction of cations (positively charged ions) on the surface of colloids and exchanged for ions in the soil solution like NH4+, Ca²+, Mg²+, Na+, H+, K+
• Anion exchange: the attraction of anions (negatively charged ions) on the surface of colloids, which are then exchanged for ions in the soil solution such (NO3-, PO4-, and SO4-) NOTE: yung 3,4,4 nasa baba at yung negative nasa taas
• • Class Y: land that is too steep, eroded, barren, and rugged, should be left for wildlife or parks
• Class A land is good land that can be cultivated safely and extensively to most crops with ordinary good farming practices
• Class B land is defined as good land which can be cultivated safely using easily applied conservation practices
• Class C land is moderately good land that can be used regularly for cultivated crops in good rotation
• Class C land needs intensive soil conservation treatments to maintain its productivity
• Class D land is fairly good land that is best suited for pasture but can be used for agricultural crops with intensive soil conservation practices
• Class D land requires intensive soil conservation practices to support agricultural crops
• Class L land is flat land that is too wet or stony, more suited to pasture and forestry
• Class M land characteristics:

  • Very steep
  • Eroded
  • Shallow
  • Better suited for pasture and forestry
• Class N land characteristics:

  • Very steep
  • Eroded
  • Rough
  • Shallow
  • Dry
  • Better suited to pasture and forestry if handled carefully
• Class N land characteristics:

  • Very steep
  • Eroded
  • Rough
  • Shallow
  • Dry
  • Better suited to pasture and forestry if handled carefully
• Class X land is level and wet most of the time, making it best suited for ponds or recreational areas
• Ammonia volatilization from NH4+ bearing fertilizers is not favored by High Cation Exchange Capacity
• Rhizobium


  Known to form colonies on the root surface, stimulating biological nitrogen fixation and providing nitrogen to the leguminous crops
• Photoautotrophs


  • Algae are considered as photoautotrophs
  • The source of energy for blue-green algae is sunlight
• Carbon-nitrogen


  Carbon to nitrogen ratio
• Ammonium


  An organic nitrogen compound which arises, for example, in small sewage treatment plants from the biological degradation of organic nitrogen compounds. Ammonium can be converted into nitrate by adding oxygen (nitrification)
• Fungi


  • Acid-loving organisms
  • Eukaryote/multicellular
• Net nitrogen immobilization in soil occurs if the C/N ratio is greater than 35:1
• Bacteria


  • Prokaryotes/single cell and have the least biomass
• 
  

  Soil microorganisms degrade organic residues primarily for carbon and energy
• Ammonium (NH4-N) - is an organic nitrogen compound which arises, for example, in small sewage treatment plants from biological degradation of organic nitrogen compounds. Ammonium can be converted into nitrate by adding oxygen.( Nitrification)
• Flooded condition

  Predominant available form of N under flooded condition is Ammonium or NH4-N
• Nitric oxide(NO3) and Nitrogen dioxide(NO2)


  Are 2 gases whose molecules are made of nitrogen and oxygen atoms
• Upland condition


  The available form of nitrogen which predominant under upland condition is Nitrate
• Anaerobic non-symbiotic nitrogen-fixing bacteria belong to the genus Clostridium
• The root-nodule bacteria belong to the genus Rhizobium
• Deposition


  Process by which sediment settles out under the action of gravity; a selective process depending on particle size, being rapid for sand and slow for clay
• 
  

  Detachment/dispersion process by which raindrops splash soil sediments from the soil surface into the run-off; requires energy that is supplied by the kinetic energy of raindrops
• Entrainment


  Transport of suspended soil particles from upslope to downhill direction whether in rills, between rills and in sheet flow
• Sheet erosion


  The uniform removal of a thin layer or "sheet" of soil from the land surface by rainfall and surface runoff
• Soil erosion


  The detachment and movement of soil from its original location
• Raindrop erosion


  Soil particles are detached due to the impact of raindrops and splashed at a longer distance in the downslope than in the upslope direction
• Channel erosion


  Occurs where surface water has concentrated, so that a large mass of water supplies the energy for detaching and transporting the soil
• Sheet erosion is the most widespread and probably the most damaging form of soil erosion
• Rill erosion


  • An erosion process in which numerous small channels of only several centimeters in depth are formed; usually the result of water washing down between rows of cultivated crops that is planted up and down the hill or in implement marks and other slight and irregularities of the soil surface