Assessment of soil EC variation and its influence on crop productivity in plastic film greenhouse

Electrical conductivity (EC) is very important in improving soil quality and an crop production under plastic film greenhouse.To improve soil heath and crop yield, soil ions of influencing EC and their effects on crop yields were investigated.Soils were sampled from 20 spinaches (Spinacia oleracea), 13 tomatoes (Solanum lycopersicum L.), and 18 green peppers (Capsicum annuum L.) farms of plastic film house.The results showed that average EC of spinach, tomato, and green pepper were 1.54 dS m -1 , 4.09 dS m -1 , and 3.49 dS m -1 , respectively.EC of spinach and tomato showed a high correlation in the order of nitrate ion > chloride ion, and green pepper was that of chloride ion > potassium ion.EC ranges with high yields were 1.0 -1.5 dS m -1 , 1.0 -2.0 dS m -1 , and 2.5 -3.5 dS m -1 for spinach, tomato, and green pepper, respectively.Crop's salt tolerance increased as cation exchange capacity (CEC) improved.Salt tolerance of tomato and green pepper with root stocks increased compared to that suggested by Food Agriculture Organization (FAO), while that of spinach with seedlings did not increase much.To maintain EC optimum range, nutrient ions that increase EC be analyzed periodically, the corresponding amount of fertilizer should be decreased during cultivation, and salt removal activities sould be carried out.