فهرست مطالب maryam salehian dastjerdi

Agricultural soils are continuously under wetting and drying cycles during flood irrigation. Large air-dry disturbed soil specimens with dry bulk density (BD) of 1. 2 g cm-3 were prepared and the effect of wetting and drying cycles on compactibility of fine and coarse textured soils was studied. The large soil specimens with/without wetting and drying cycles were compressed under three preloads (0، 100 or 200 kPa) and then the small soil samples for water content and bulk density measurements were removed. The results showed that the wetting and drying process resulted in increase in an BD for both soils without applying any compacting load. This process resulted in soil susceptibility to compaction for coarse textured soils، whereas it increased the resistance to soil compaction for fine textured soils. Therefore، in fields with coarse-textured soils and under flood irrigation، are more sensitive to soil compaction at harvest traffic at both soil conditions as compared with the fine-textured soils. Therefore، with reducing contact pressure and axal loads the soil compaction could be prevented.