Evaluate of subsurface drainage performance at second crop of paddy field (Case study: Triticale in physical model scale)

In order to evaluate the performance of subsurface drainage, a study at physical model scale in condition of second crop paddy fields was done. In the physical model, drains were installed in two depths 40 (D40) and 60 (D60) cm at two separate boxes and triticale was cultivated after rice harvest. In the time of rain, drainage sample parameters include EC, SAR, pH and TSS were measured in the laboratory. The water table was read by piezometer. The results showed that with increase in drainage depth, EC was increase and SAR value declined. Trend of EC was decreasing throughout the experiment, so that EC value at the end of experiment period for two drainages D40 and D60 decreased with a rate of 53% and 8% compared to the start of period. TSS values and trend throughout the experiment demonstrates the use of geotextile at the roles of its cover. It was found that the drainage installed at a depth of 40 cm can be more successful in the control of soil drainage and prevent waterlogging.