hydraulic conductivity

Sara, 1st consider Darcy's Law q = -K (dΨ/dx) q (the flux density) is proportional to the water potential gradient BUT it also depends on K (the hydraulic conductivity, which varies with soil water content)

Have a look at the graph of hydraulic conductivity versus soil matric potential in the class notes (slide 19 in lecture #11). Your thinking is correct, that K is maximum when the soil is saturated, i.e. all pores are filled with water; but consider how K changes as the soil matric potential (and consequently the soil water content) change. Note to be careful to distinguish between K and dΨ/dx