Effect of Shape, Size of Pores on Saturated Hydraulic Conductivity of Some Iraqi Soils

Volume 16 , Issue 1 , October 2014 , Pages 157-175

Authors

¹ Dep. of Soil Science and Water Resources, University of Baghdad-College of Agriculture,Baghdad

This study aims to find out the effect of shape, size of pores on saturated

hydraulic conductivity. Ten pedons were selected from the north of Iraq; five pedons

were selected from Sulamani province: Bakhteari forest, Bazian, Choesoor, Kanakow

and Sarsank was from Duhok province. While in the middle sites, five pedons were

selected from Baghdad, two from college of agriculture, Al-Tarmia, and Al-Raeed

experimental station, the last pedon from Al-Anbar province – Al-Husaenia. Disturbed

and undisturbed soil samples were taken from surface and subsurface horizons from

each pedon. Some chemical and physical properties were determined, which include

texture, carbonate minerals, free iron oxides, organic matter, bulk density, porosity and

hydraulic conductivity. Also they were used for micro morphological characterization as

thin section and scanning electron microscopy. The results indicated that the highest

value of saturated hydraulic conductivity of the northern sites were 77.73cm.hr-1

at P4A1(north), the lowest value was 0.47 and 0.47 cm.hr-1 observed in surface and subsurface

horizons of P3 . The high value of middle sites was 9.89 cm.hr-1in P9A1; the lowest value

was 0.89 cm.hr-1 in P8C1. Micro morphological characterization showed variation in the

shapes and size of pores for all studied horizons. Also, they showed coating and filling

material affecting the pores. The dominant shapes were channels, chambers, voids. The

results show that there are differences in shapes and size of pores between north and

middle sites, where the dominant shapes of pores in middle sites were chamber and

packing. The results showed the existence of free iron oxides which increased MWD and

bulk density and decrease hydraulic conductivity and porosity; also it's forming type of

shape as small chamber. Organic matter forms meta vughs which make the hydraulic

conductivity high because this type of shape is more stable.

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