Relationship between k and ym

• At saturation the most conducted soils are those in which large and continuous pores constitute most of overall pore volume, while the least conductive are the soils in which pore volume consist of numerous micro-pores.
• Thus, sandy soil conducts water more rapidly than the clay soil. However, the opposite is true for unsaturated soils.
• In higher suction, the larger pores quickly empty and become non-conductive as suction develops, thus steeply decreasing the initial conductivity.
• In a soil with greater amount of soil pores, may have micro-pores full of water and conductive even at appreciable suction. Thus, K does not decrease with soil moisture content in clay soil as like of sandy soil and retain water greater than that of a soil with larger pores subjected to same suction.
• Since soil in field condition is unsaturated most of the time, water movement is appreciable and persists longer in clay soil than in sandy soils. Thus, with increasing metric suction the conductivity decreases but in differential rate in clay and sandy soil. This gives why water movement is impeded in stratified soil layer.