Abstract :
ABSTRACT: Increasing soil organic carbon (SOC) is vital in terms of improving the soil physical and mechanical properties related to conditions for tillage and traffic, and to crop development in arid and semiarid regions. This laboratory study was aimed to assess effects of SOC on soil consistency limits (liquid limit, LL; plastic limit, PL; plastic index, PI) and soil compactibility parameters in soils with different textures (clay, silty clay, silty clay loam and clay loam). The SOC, consistency limitsand plasticity index (PI = LL ? PL) were measured for the soil taken from the 0–30 cm layer. The SOC varied from 0.3 to 1.28%. The lowest SOC was recorded in clay loam soil texture, whereas it was the highest in clay soil texture. The results of this study showed that soil organic carbon content significantly enhanced soil mechanical properties and reduced soil compactibility.The SOC in all experimental soils significantly (p < 0.01) increased liquid limit (LL) plastic limit (PL), and plastic index (PI) values. The highest LL, PL and PI values were obtained in clay-textured soil. There was a significant relationship between the SOC and the Atterberg limits and plastic index. The positive relationship between SOC and PL, LL and PI was found to be significantly linear. Regression analysis for Atterberg limits in four soil texture class showed that the SOC were important character on liquid limit, plastic limit and plasticity index.The LL for the clay soil texture was significantly higher than the LL and PL on other soil textures. The PL and PI were increased significantly but in small percentages by the SOC increasing as compared with the LL. The effectiveness of SOCon LL, PL and PI was more pronounced in soils with high clay content.This study showed that the SOC improved soil plasticity. Moreover, the improvement depended on the rate of the organic carbon content and soil texture. The results presented in this study clearly indicated that SOC lead the soils more strength to mechanical forces.The result revealed soil plasticity has direct correlation with soil organic carbon content.
