Analysis of saline groundwater infiltration into two loam soils

Irrigation with saline groundwater may cause salt accumulation in the soil and even land degradation in coastal areas. The aim of this study was to reveal how the changes in groundwater salinity affect the infiltration characteristics under controlled conditions. One-dimensional vertical infiltration experiments were conducted in uniform columns of silty clay-loam and sandy-loam under different salinity levels of irrigation groundwater (0, 1, 2, 3, 6, 9, and 12gL(-1) NaCl). The results showed that as groundwater salinity increased, the infiltration capacity of the silty clay-loam increased under low salinity levels but decreased under higher salinity levels, with a turning point at the salinity of 6gL(-1) NaCl. However, there were no significant differences in the infiltration capacity of the sandy-loam under salinity levels of 1-9gL(-1) NaCl, whereas a significant increase was found under 12gL(-1) NaCl. The infiltration capacity of the sandy-loam was consistently higher compared with the silty clay-loam under different salinity levels. Under short-term irrigation with a conventional amount of 750-900m(3)ha(-1), extracting groundwater with the salinity of <6gL(-1) NaCl obtained higher desalination efficiency in the silty clay-loam and resulted in less salt accumulation in the surface soil (0-20cm). Under the same amount of irrigation with groundwater containing 1-12gL(-1) NaCl, the increase of soil salt content was relatively small in the sandy-loam and might not significantly affect crop growth.