Studies on Salt and Water Movement in Secondary Salinized Greenhouse Soil under Subsurface Drainage

The secondary salinized greenhouse soil was provided with subsurface pipe drainage system with drainage spacing 6 m and drain depth 0.4m to study the movement of salt and water. The field investigations indicated that the resalination rates of the surface soil with subsurface drainage system were lower than those with non-drained system (CK) in an irrigation circle of the crop. The resalination rate of the surface soil right above the drainage tubes (T1) was significantly lower than that between the two drainage tubes (T2). At the 5th day after irrigation, the soil volumetric moisture contents of different treatments were significantly decreased and the resalination of surface soil were obvious. The results showed a considerable increase of resalination rate after irrigation that was varied at the 5th day as following sequence: CK(10.6%) > T2(8%) > T1(7%).