Improvement effect of subsurface drainage on secondary salinization of greenhouse soil and tomato yield

In order to solve the problem of secondary salinization of greenhouse soil, a subsurface drainage system was set up with plastic bellows buried in the soil of the greenhouse to probe into the measures against secondary salinization of soil, and to study the changes of soil basic physicochemical properties through subsurface drainage. Soil electrical conductivity (EC), soil saturated hydraulic conductivit, bulk density, porosity and yield of tomato were studied. The system was installed with two arrangements, space of 6 m and depth of 40 cm; space of 8 m and depth of 70 cm. Results showed that the subsurface drainage system lowered the EC of different soil layers, especially the EC of soil which above the subsurface drainage. Meanwhile, saturated hydraulic conductivity of soil increased, bulk density decreased, but bulk porosity increased. The tomato yield increased as the average weight of single fruit increased. All these indicators of the system with space 8 m and depth 70 cm were better than those of the system with space 6 m and depth 40 cm. It is concluded that the effect of drainage system with space 8 m and depth 70 cm on improvement of soil secondary salinization was more significant than that of the system with space 6 m and depth 40 cm in greenhouse.