An assessment of Haloxylon succession on some Surface soil quality indicators in Taybad sandy lands, Khorasan province

Mobile sand is the biggest obstacle to sustainable development in arid and semi-arid regions of Iran. The most effective way to maintain and promote sustainable development is reform and recovery of vegetation in these areas. Mobile sand stabilization has a great influence on soil conservation and minimizes erosion in Taybad. Regarding to existence of reclaimed sandy lands which is caused by the Haloxylon sequence, the rate of change on physical (soil texture and bulk density) and chemical characteristics (EC, pH and CaCO3) and soil erodibility indices (MWD, CR, MCR) were studied in the area. For this purpose, five sites were selected based on Haloxylon age (41, 28, 19 and 11 years old and a control site (no Haloxylon plantation). Considering planting age Haloxylon, the results represent a 24, 14 and 8% reduction, respectively in sand, silt and clay contents. Similarly, bulk density was reduced from 1.57 to 1.37 g/cm-3. Maximum weighted average diameter (2.48 mm) was belonging to 41 years old-Haloxylon plantation while minimum value (0.85 mm) was observed in control site (without any plantation program). Moreover, highest amount of pH (8.4) was observed in the 41 years old-Haloxylon plantation and lowest pH (7.4) was measured in control site. The oldest Haloxylon plantation (41 years old) caused maximum amount of electrical conductivity (EC) (0.7 dS m-1) and the lowest value of EC (0.33 m-1) caused by control treatment. The amount of calcium carbonate changed from 0.33% in control site to 0.6% in 41 years old Haloxylon. The results showed that many of soil physico-chemical properties were improved as Haloxylon afforestations became older.