The effect of land use change on physical indicators of soil from rangeland to dry farming in the beginning and the end of the growing season in Freidan region of Isfahan

Rangelands represents the largest land resource in the world and therefore are important from economy and environmental perspectives. Improper use of natural resources including soil causes its degradation and results in severe soil erosion. Therefore a study was conducted in Friedan in Isfahan province in 2010. The objective of this study was to compare selected soil physical indices in a rangeland with good vegetation cover (>20%), dry land forming and a degraded dry land form which is used in three slop (0-10, 10-20, 20-30). Land was selected in such a way that changes them for the past 10 years and the geology and vegetation types and manages the same. The composite surface (0-15 cm) soil samples to determine physical properties of soil such as particle density, bulk density and water disperse clay and hardness of surface soil. A rainfall simulator was run for 40 minutes whit 20+5 rainfall intensity to stimulate the amount of sediment, runoff and sediment concentration. Data was analysis with SAS and compared by Lsd test. The highest porosity was observed for pasture with good vegetation. Maximum gradient of 30 to 20 percent in the runoff for degraded dry land form in September 2197 to the amount of cubic centimeters per square meter was observed. The largest amount of sediment in dry land form and steep for 30 to 20 percent in the September to 15.7 grams per square meter was observed. The highest sediment concentration 20.3 grams per liter and a 30-20 percent dip in August was the season. Poor management and non-normative caused the reduce of soil productivity in the long term.