Removal characteristics of salts of greenhouse in field test by in situ electrokinetic process

The addition of excessive fertilizer to the soil in greenhouse makes salts accumulate in the soil, such as nitrate, sulfate, sodium and soon. As a result, productivity of crops in greenhouse decreases and the quality of crops is also deteriorated. In this study, electrokinetic (EK) technique in a field was applied to remove the salts from the soil in a greenhouse for growing chrysanthemum. EK experiments were carried out for 2 ridges with dimensions of 3 m in length and 2 m in width. Initial electrical conductivity (EC) of the soil was extremely high (20-60 dS/m), but it varied too much with positions due to the heterogeneity of the soil. Electrode modules implanted in each furrow were composed of 4 anodes and 3 cathodes. High Silicon Cast Iron (HSCI) rod and Fe plate were used for anode and cathode material, respectively. In this study, we introduced the EK systems which equipped electrodes, data acquisition system, water supplying to the soil, and EOF drain system in greenhouse. In order to check the process during EK experiments, we monitored total current, total voltage, the current of each electrode, and the temperature of soil with variable positions. After applying a constant voltage (similar to 0.8 V/cm) to the soil for 2 months, EC change, pH change, moisture, and salts concentrations such as Na+, K+, Cl-, NO3-, and so on were investigated with different positions. Experimental results showed that in situ EK technique reduced the concentration of main salts such as sodium, nitrate, and chloride to 90% effectively. However, other salts such as sulfate, magnesium, and calcium were not removed from the soil effectively. The effects of in situ EK technique on the removal of salts from the soil of greenhouse were discussed. (c) 2012 Elsevier Ltd. All rights reserved.