Increasing of population growth rate and need for food forced farmers to invade marginal lands like pastures and forests with little crop potential. In last four centuries about 30% of lands of forests and pastures are changed to cultivation lands. This had lead to removing soil organic matter and increasing CO 2 production and its emission into atmosphere. Changing in land use, has also lead to degradation of soil structure. This study investigated the effects of changing forest and pasture into crop lands on organic matters and some physical properties of soil. Two locations of Fraidan( as pasture) and Lordegan(as forest) were used. In each area two land use was selected. One under cultivation and other one was unaltered. In each land use three sites were selected and in each site three depth 0-1, 1-5 and 5-15 centimeter were sampled. Soil texture, percent of organic matter, electrical conductivity and soil pH were determined on disturbed samples and aggregates stability, hydraulic conductivity and bulk density were determined on the undisturbed soil samples. Soil water repellency was determined both in laboratory and field. Fractal dimension was used for evaluation of aggregate stability and was compared with mean- weigh diameter. Result showed that change in land use had significant effect on some of measured parameters. Intensity of these changes were higher in forest. Also, soil water repellency was found just in unsalted forest. With increasing soil organic matters, soil water repellency intensity was increased. Fractal dimension was increased in forest and pasture with change in land use. The most fractal dimension was found in unalter pasture. comparing CVs between fractal dimension and mean- weight diameter showed that fractal dimension is a better index than mean- wight diameter and had more accuracy. Because of high correlations between fractal dimension and measured parameters, it can be said that fractal dimension is a more suitable index for evaluation of soil decomposition with change in land use.
