Dynamics of soil water and temperature in aboveground sand cultures used for screening plant salt tolerance

There are increasing concerns about the feasibility of applying plant salt tolerance information obtained from artificial sand cultures in field soils. A main question concerns the similarity of growth conditions between the sand cultures and the field. This study was conducted to determine the dynamic variations of soil water and temperature in sand cultures and to compare them with the same parameters observed in a field soil. Results indicated that sand cultures filled with a reasonably well graded river sand exhibited values of minimum and maximum soil water content similar to those in the field. Soil volumetric heat capacity and thermal conductivity of the riser sand were also comparable with values found in the field soil. A poorly graded silica sand, however, was found not suitable to reproduce soil water and temperature regimes that commonly occur in the field. If other environmental factors for plant growth can be simulated to match those found in the field, results of plant salt tolerance obtained from the sand cultures can be used to provide guidance for plant selection under field conditions. The approach of using particle-size analysis information to derive the hydraulic and thermal properties should be readily adoptable by interested researchers in selecting the most appropriate grading of sand culture materials.