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Silty clay soil sample was chosen from the surface layer (0-0.3 mm) from Al-Rashidia field and passed through a series of sieves to get aggregate size range from 0.4-6mm to study the effect of there sizes on water properties of the soil. Results indicated that the stability of different aggregate size were significant which represented by mean weight index. While the small aggregate size (0.04-3.00 mm) was significantly different in water holding capacity at the tension near field capacity compared with the large aggregate size (4-6 mm) which was significant at the tension near permanent wilting point. On the other hand, the ability of the small aggregate size of the diffusivity, penetrability and sorptivity were highly significant compared with the medium and large aggregate size. The hydraulic conductivity were highly significant for the medium and large aggregate sizes compared with the small aggregate.

This study was conducted at three locations differ in their textures and land uses at Nineva Governorate to estimate the matric potential at wetting front under field condition for both planted / unplanted soils, by applying some equation depends on hydraulic functions during water infiltration in double ring infiltrometer. Results indicated that the values of matric potential at wetting front as a function of volumetric water contents were more accurate than the values of matric potential as a function of the hydraulic conductivity . On the other hand , results indicated that the value of matric potential as a function of both soil texture , saturated and unsaturated hydraulic conductives were diffrent. Also, the value of matric as a function of measured and calcluted air- entry were relatd to pore size distribution .