Soil texture

• soil texture


  is the size and shape of soil particles
• limitations of the productivity of clay soil

  1. hard to till because of cohesive forces and closely packed particles
  2. water-logging occurs very easily
  3. aeration is bad because of fine texture
  4. clay layers limit root growth and development
  5. it is difficult to irrigate clay soil because the absorption of water is extremely slow
• Clay soil


  • Large total surface area for chemical reaction
  • Erodes slowly due to loosely packed particles
  • Increased soil fertility due to large surface areas which enables colloids to absorb plant nutrients
  • Low percentage macro pore space, limited aeration and drainage
  • Plastic and sticky, difficult to till
  • Adsorbs water as thin film on colloids
  • Large surface area ensures high water retention
  • low heat conduction
• Sandy soil


  • Small total surface area for chemical reaction
  • Erodes quickly because it has large loosely packed particles
  • Absence of colloids means low fertility
  • High percentage macro pore space, good aeration and drainage
  • Easily tilled due to low cohesive forces
  • Low water retention ability due to larger soil particles
  • Macro pores allow for drainage
  • high heat conduction
• Soil particle sizes by diameter

  • Clay: less than 0.002mm
  • Silt: 0.002-0.05mm
  • Sand: 0.05-2mm
• Field methods of determining soil texture

  • Feeling method
  • Sausage method
• Feeling method


  Rubbing soil sample using the thumb and 4 fingers
• Sausage method


  Rolling the soil into a sausage
• reason of knowing the texture class of the soil

  • To adopt the crop production adapted to the characteristics of soil/

  to make crop choices

  • To know when to cultivate and which implements to use

  • To be able to assess the efficacy of fertilisers

  • To know the type of irrigation to use

  • To understand how soil will react better to temperature

  changes
• Heavy soil

  clay soil
• Light soil

  sandy soil