Effect of solid phase wettability on water transport and retention in peat enriched soil affected by freezing/thawing**

A b s t r a c t. Samples of A and B horizons of arable loessial soil, with and without the addition of c.a. 9% of peat and subjected to six freezing/thawing cycles, were studied. Surface free energies and water contact angles were determined using a thin layer wicking technique. The water retention curving relating soil moisture to the pressure head was measured by combining the suction plate and pressure chamber methods. The addition of the fresh (non-dried) peat increased soil wettability in both horizons, which increased further after cyclic temperature changes. The amount of water retained at high pressure head values (in the low moisture region) decreased with the decrease in soil wettability, i.e., with the decrease in the work of spreading of water and the increase of the contact angle. However, the amount of water retained at low pressure head values (in the high moisture region) depended on the pore volume of the soils. It was concluded that the value of the surface free energy has an important effect on water retention at low soil moistures, whereas at high moistures, macroscopic soil characteristics (such as porosity or bulk density) govern the water retention.