Zinc Phytoremediation By Corn (Zea mays L.) Grown with a Slow Release Fertilizer.

Among heavy metals, zinc (Zn) is most produced in the world next to copper. Zinc contamination in soils is worldly recognized and its concentration is relatively high compared to other heavy metals. Among remediation methods, phytoremediation can be superior to chemical and physical treatments in terms of low costs, extensive application, and low environmental impacts. However, phytoremediation may not be as effective as others in removing heavy metals in large quantity from contaminated soils. To enhance removal efficiency, it is imperative to improve both plant biomass and absorption rates for heavy metals. It has been reported that slow release fertilizer (SRF) is effective for improving plant biomass compared to other soluble chemical fertilizers. Also, reducing soil pH may free up Zn ion in soils that may enhance the plant absorption rate. Therefore, objective of this study was to evaluate effects of application of SRF and reduction of soil pH on Zn phytoremediation by corn (Zea mays L.).

A Typic Dystrochrept (Tokyo, Japan) was used to create Zn-contaminated soil samples with varying concentrations (0, 200, 400, 600 mg Zn kg^-1) at the original soil pH (7.6) and reduced pH (6.0), respectively. After applying fertilizers (urea or SRF) a corn was cultivated in a pot for 30 days. After harvest, dry weight and Zn content of plants were analyzed.

In only original pH soils, SRF treatment showed significantly higher plant dry weight than urea treatment. There was a significant difference in plant dry weight between SRF and urea treatments in 400 mg Zn kg^-1 contaminated soils. It was found that SRF could improve plant biomass due to slow release capability of fertilizers. Also, SRF treatment showed significantly higher Zn content than urea treatment. There were significant differences in Zn content between SRF and urea treatments in 200, 400, 600 mg Zn kg^-1 contaminated soils. It was shown that SRF might positively affect Zn remediation by corn by improving plant dry weights.