Document Type : Research Paper
Concerns about nitrate pollution in groundwater and downstream systems Cause development of surface water management system to reduce losses of agricultural drainage water nitrate in subsurface drainage Using subsurface irrigation from existing drainage lines, drainage water during the growing season and out of season is controlled. The overall objective of this study was to evaluate the effect of controlled drainage on nitrate losses via drainage outlet and a physical model used to simulate the conditions of a real farm. Plan includes of six treatments, one treatment free drainage (FD) output at a depth of 80 cm from the soil surface drainage and controlled drainage treatments (CD1, CD2), which drains the water table controlled at 45 and 25 cm, respectively, at a depth of the soil surface. Each level has two drainage treatments applied nitrate fertilizer (urea) N1 (100 percent) and N2 (50 percent). The results showed that the amount of drain output, there are significant differences between the treatments drained (P< 0.0001 , F=45.42). Controlled drainage treatments (CD1 and CD2) compared with treatment FD, 57.9 and 80.5 percent have reduced the volume of drainage water, Respectively, and CD2 treatment the amount of drainage water compared with CD1 treatment 53.8 percent reduced. 100 percent of the nitrate fertilizer, controlled drainage(CD1 and CD2) in comparison with free drainage (FD) rates of nitrate loss to the 55.8 and 82.5 percent have reduced, And 50 percent of nitrate fertilizer, the amount of nitrate loss from controlled drainage to the 30.3 and 70.4 percent, respectively. Controlled drainage can be improved to reduce the role of nutrients in the soil and reduce nitrate removal.