Some physical properties of soils with different gypsum content in northern Iraq sites

Abstract

six location in Nenevah governerate (Khafaja , Aski Mosul and Abu Mariyya), have been chosen for collecting soil samples with gypsum content (86, 101 and 76.4 gm kg -1 ) respectively, and soil samples were collected for (0-30 cm) depth . In addition , (Al-Iyyadyah , Ain Talawi and Sino) locations were also selected for collecting other soil samples in gypsum content between (444.4 - 830 g m kg-1 ) . Soil samples were in two depths (0-15 cm) and (15-30 cm) ..For estimation gypsum percentage , the current work used four methods including (Rechard 1954 , Barium Sulfate 1988 , AL Mufty 2000 and Artieda 2006 ) ,while artificial gypsum were used as acontrol . Artieda method showed highest values of (artificial gypsum ) , and thus was used as the best method . The first three soils had a clay texture , while increasing the percentage of gypsum in the remaining of the studied soils made it difficult to estimate the percentages of soil separators .The results of this study showed the inverse relationship between the percentage of gypsum and calcium carbonate in the gypsum soil of the study location in the direction from the city of Mosul towards the Sinjar district . The increase in the gypsum percentage is accompanied by a decrease in the percentage of total calcium carbonate.The study showed that soil samples of the first three locations , it s saturated hydraulic conductivity values increase with a decrease in the percentage of fine particles in the soil . Additionally , the increase of gypsum percentage in the gypsum soils leads to a reduction in the values of the saturated hydraulic conductivity values , while the increase in the percentage of calcium carbonate was accompanied by an increase in the values of saturated hydraulic conductivity. The values of the instantaneous infiltration rate indicate that they differ between the study sites depending on the initial moisture content , texture and structure of the soil. Al Khafaja soils observed low basic infiltration rate 50% compared to gypsum soils, with an increase in the gypsum percentage at the locations (AL-Iyyadiah , Sino and Ain Talawi ) (15 - 60%), accompanied by a reducion in the values of the basic infiltration rate (66-20%) , the gypsum soils has a cumulative infiltration values during the measurement period of 120 minutes, which is higher than the another three locations soil due to its high ability to impregnate and retention moisture under low tension..From the results of (dry and wet) sieving , it was clear that the values of the mean weight diameter in first three soils were similar. In gypsum soils the mean weight diameter increased , especially after the limits of 700 g kg-1 of gypsum content . The results of Atterberg limits (shrinkage limit, lower plastic limit and upper plastic limit ) and clay effectiveness were different for first three soils (where this property could not be obtained in gypsum soils).