Soils with highorganic content, which are called organic soils, are one of the soil types that cause many problems forengineering construction. In this study, a sample has been taken from Al-Hayyaniyah site and measuring their organic content. To identify the behavior of some geotechnical properties of cohesive soil in the presence of different organic content, animal manure is added to soil to make a mixture of soils having 1, 2, 3 and 4% of the organic matter. The natural soil and these four samples are prepared and performing the geotechnical test such as Atterberg limits, unconfined compressive strength, and direct shear strength. The result showed that there is increase in Atterberg limits (liquid limit, plastic limit, and plasticity index) with an increase of the organic matter content, while the cohesion values decrease from 36 kPa in the natural soil to 18 kPa in treated soil having 4% of organic matter and the values of the angle of internal friction reaches 14 and 12 degrees in the 1 and 2 % of the organic matter added and then decreased to reach 6 degrees in the 4 % of the organic matter added. The unconfined compressive strength also decreased from 713.37 kPa in the natural soil to 540.23 kPa at the same above values 4% of organic matter.