Salt removal of greenhouse soils using electrokinetic technology

摘要

Excess nutrients are easily accumulated in greenhouse soils due to the interception of rainfall by plastic film and repeated over-application of compost and fertilizers. This study was conducted to evaluate the application of electrokinetic (E/K) technology for salt removal from soils with high electrical conductivity (EC) in greenhouses. Three types of soil in plastic film greenhouses were used: artificial soil (Site A), poorly drained soil (Site B), and well-drained soil (Site C). The salt-enriched surface soils were used to fill 37-cm-long-box-type E/K cells, and a constant voltage gradient was applied at a rate of 1 V cm(-1) for 30 days. The decrease in soil EC was achieved with water content of greater than 30% for silt loam (Sites A and B) and 20% for sandy loam (Site C). The E/K technology decreased soil EC by more than 80%, with a greater reduction ratio for sandy loam than for silt loam. After 30 days of the E/K treatment, 98-99% of NO3-N and 95-99% of sodium were removed in all three sites under saturated condition, implying that nitrate and sodium ions had higher mobility than the other ions during the E/K process. The results obtained from the study suggested, therefore, that the E/K technology is highly efficient for wet and nitrate-enriched sandy loam soils, and the technology can be a feasible and environmentally sound practice for the removal of excessive nutrients in greenhouse soils without water pollution by nutrients such as nitrate as can be caused by flooding and repeated washing with water.