Effects of municipal solid waste compost (MSWC) application on certain physical properties of soils subjected to freeze–thaw

Abstract

Freezing and thawing (FT) processes have great importance on the physical, chemical and biological behaviours of soil. In cold regions, soils are exposed to a freeze–thaw cycle every year, especially during late winter and early spring. The quality of soils exposed to FT can be improved with the addition of waste, which contains appropriate levels of organic matter. This study was conducted to determine the effects of municipal solid waste compost (MSWC) applications (0 (control), 10%, 20%, and 30% volume/volume (v/v)) on bulk density, aggregate stability and permeability coefficient of soils with different electrical conductivity (EC) and exchangeable sodium percentage (ESP) subjected to freezing and thawing processes. Increases in the application doses of MSWC decreased the soil bulk density in the 0 FT cycle. However, the bulk density of soils subjected to freeze–thaw cycles showed differences. Among the freeze–thaw cycles tested, the lowest bulk densities were observed with 6 cycles in Soil I, 0 cycle in Soil II and 0, 3 and 6 cycles in Soil III. Municipal solid waste compost applications significantly increased the aggregate stability of all the soils subjected to freeze–thaw compared with the control. In Soil I, the highest aggregate stability was obtained with 9 cycles in a 10% dose. As compared with the aggregate stability of the 0 cycle for Soil II, the aggregate stability of Soil II decreased with the rates of 12.16% and 21.73% for 3 and 6 cycles, and increased with a rate of 16.82% with 9 cycles. In Soil III, the highest aggregate stability values of the control and 10% dose was obtained from 9 freeze–thaw cycles. Municipal solid waste compost applications significantly increased the permeability coefficient of all the soils. In Soil II, the highest permeability coefficient was obtained with 6 cycles, although no significant differences were found between cycles. The results presented in this study have shown that MSWC application not only reduces the negative effects of freeze–thaw cycles, but also improves the aggregate stability and permeability coefficient of saline-sodic soils, which could enhance leaching and therefore help reclamation of these soils.