Solute Movement in Multi-Layered Reclaimed Soils With Macroporous Subsurface Layer Utilizing a Coal Bottom Ash(CBA).

Serious problem in reclaimed land is high soil salinity and very poor vertical drainage, so desalinization in these soils is very difficult. Although desalinization is accomplished in top soils, before long, soils are resalinized according to capillary rise of salts from the subsurface soils. To resolve these problems, multi-layered soil columns with subsurface layer of macroporous medium utilizing coal bottom ash(CBA) were constructed and the effects of promoted desalinization and blocked resalinization of these soils were investigated. The pHs for surface and subsurface soil were 7.7, 7.8 and the ECs were 33.9 dS m^-1, 14.7 dS m^-1 respectively. Experimental soils were classified as saline-sodic soil. The K_sat of surface and subsurface soils was 0 cm sec^-1, so experiments were conducted for multi-layered soil columns with top soil incorporated with gypsum at 5 cmol_c kg^-1. In top soil(30cm)+CBA(30cm)+subsurface soil(20cm) column, stabilized K_sat was 0.31×10^-4cm sec^-1, While in top soil(30cm)+subsurface soil(20cm) column, K_sat was 0.064x10^-4cm sec^-1. In capillary rise experiment, overall rate of capillary rise was 2.38 cm hr^-1 for top soil(60cm) column, while 0.08 cm hr^-1 for top soil(30cm)+CBA(10cm)+ subsurface soil(10cm) column. In multi-layered soil columns with CBA 20, 30cm layer, wetting front due to capillary rise could not be seen in top soil layer and cations in top soil maintained at low level because CBA layer cut off capillary rise of salts from the subsurface soil. From these results we could conclude that the macroporous layer utilizing coal bottom ash placed at subsurface layer enhanced leaching of solutes from the top soil and cut off capillary rise of solutes in multi-layered reclaimed soils.