NON ERODIBLE FRACTION OF ARID AND SEMI ARID REGIONS

The aim of this study was to determine some of the mechanical characteristics of the non crdible fraction (> 0.84) of six soil sits in arid and semi regions / north Iraq .These characteristics included ; Rate of deaggregation (RD)and potential stractural deformation index (PSDI).The results showed that . RD of the non erodible fractions was decreased with increasing the time of dry sieving . The PSDI values also decreased as a result of wetting of the dry non-erodible fraction .This varition may cause a strong destruction of this fraction due to the raindrop impact during winter season