TEMPORAL CHANGES IN SOIL PHYSICAL AND HYDRAULIC PARAMETERS FOR DIFFERENT TILLAGE PRACTICES IN NORTH OF KHUZESTAN PROVINCE

The hydraulic and physical properties of soil have important role in design irrigation and drainage projects. Variability of hydraulic parameters of soil is very high depending on time and space. In order to study these variations, a field experiment was carried out in a randomized complete block design with three treatments and three replications in a corn field in North of Khuzestan (Dezful) in 2013. The treatments were including No tillage (NT), Minimum tillage (MT) and conventional tillage (CT) practices . The measurements using a disc Permeameter in different suctions (zero, 3, 5, 10 and 15) in four times include as: before irrigation and in second, eighth and tenth irrigations was performed. The data was measured from depth of soil (10 and 20 cm) and in different times was analyzed by split plot design in time. The results showed that the tillage practices  and depth of measuring and their interactions had a significant effect at 1% level on apparent density of soil. The saturate and nearly hydraulic conductivity in CT was significantly more than the other tillage practices  (NT and MT) and in the MT and NT hydraulic conductivity is nearly equal. There was significant difference between different times in all suctions, except of the suction 15 and Gardner .  The initial soil moisture had an important role on variability hydraulic conductivity in time. The interaction effect between tillage and time was significant only in saturated hydraulic conductivity.