Intermittent leaching of copper from copper based fungicide through a saturated soil profile

Abstract

Copper is a micronutrient required for plant growth. However, it can have negative effect on plant growth if the concentration is too high. The aim of this study was to examine copper concentrations of leachate from soil columns treated with copper based fungicide. A 2 × 4 factorial arrangements consisting of two soil types (0 to 60 cm sample depth) and four rates of copper based fungicide concentrations (0, 1.88, 3.75 and 7.50 g/L ) was used with three replications. The column leaching experiment was conducted by saturating the soil profile with water at 5 mm/h rate of water flow for 1 day. After saturation, the fungicides was applied and the soil columns kept completely saturated with water by maintaining ponding by continuously applying de-ionized water at a rate of 10 mm/h throughout the experimental period. The process was repeated three more times. Leachate samples were collected every 6 h for 7 days and analyzed for copper using Atomic Absorption Spectrophotometer. The results indicated that drainage time, soil type and fungicide concentrations significantly (p < 0.01) effected copper concentration in the leachate. Highest metal concentration in the leachate was obtained between 2.5 to 3.25 days. On the average, the concentration of copper in the leachate during the first fungicide application and leaching was 1.94 mg/L. This concentration reduced to about 1.12 mg/Lduring the second application. It was also observed during the experiment that the flow rate of water decreases during the leaching of the second fungicide application. The concentration then increases to 1.85 and 2.83 mg/L for the third and fourth applications, respectively. Repeated application of the metal through the fungicide leads to the accumulation of the metal in the soil.