In recent years, numerous attention has been focused on the use of agricultural soils for mitigation of atmospheric CO2 through sequestration of soil C. Land-use type and management practices are important factors controlling organic matter storage in soils because the effects which has on the amount and quality of litter input, the litter decomposition rates and the processes of organic matter stabilization in soils. However, soil organic matter quantity and quality in relation to land-use changes is poorly understood for native pastures of arid and semi-arid regions. Pastures in arid and semi-arid areas are characterized by low rainfall, low fertility, and overgrazing. Soil carbohydrates and particulate organic matter (POM) are the main component of the pool of organic matter (OM) most affected by land use .Since carbohydrates and soil microbial activity are typically concentrated in the top few centimeters of soil, changes in chemistry near the surface (such as increased salinity) could affect soil microbial activity and carbohydrates content. Thus salinization is another process affecting C sequestration in these regions. Estimates suggest that about 34 million ha, are salt-affected in Iran as the consequence of naturally occurring phenomena and anthropogenic activities. The aim of this study was to determine the response of soil carbohydrates and POM to increased salinity and changes in land use from permanent pasture (overgrazed) to wheat cropping systems occurring in Javanmardi plain, Lordegan Iran . Three sites in Javanmardi plain were selected for sampling. Two sites as pasture and cropland soils and one site with salt-affected cropland soils were used. In each site two depths 0-5 and 5-15 centimeter were sampled. In soil samples dilute acid-soluble carbohydrate, hot water-soluble carbohydrate, cold water-soluble carbohydrate, particulate organic matter in microaggregate and macroaggregate, ESP, CEC and exchangeable cations (Ca, Mg and Na) were determined. Land use change (i.e. conversion of pastures to wheat cropping systems) resulted in significant increases in organic C, total N dilute acid-soluble carbohydrate, hot water-soluble carbohydrate, POMmicro and POMmacro contents. Nonetheless, land use change resulted in significant decrease in cold water-soluble carbohydrate content. Also, land use change resulted in significant decreases in Clay, ESP and exchangeable Mg contents. Changing land-use had no significant effect on mean amounts of exchangeable Ca. The significant positive relationship between hot water-soluble carbohydrate and EC, demonstrates the extremely negative affects that increasing salinity had on the soil microbial activity. No significant relationship was found between EC an