Co-application of Animal Wastes and Micrococcus sp. in Bioremediation of Zn-polluted Soil and Analysis of Their Effects on Corn Seedlings

Abstract

Cow dungs and poultry wastes (organic supplements) were co-applied with Micrococcus sp. (plant growth promoting rhizobacteria), both individually and in consortium. This was aimed at understanding their effects on bioremediation of Zn-polluted soil and the growth of corn seedlings cultivated on it. After a period of treatment and growth, different parameters of the soil, and corn seedlings growth on them, were analyzed. Results revealed that the pH, OC and SOM contents of soil samples amplified at the end of treatment period, excluding the control samples. Samples treated with poultry wastes and Micrococcus sp. only, recorded 18.64%, 21.01% and 26.00% increase in pH and 114.12%, 131.68% and 147.93% increase in OC at 33.75 mg/kg, 42.02 mg/kg and 52.55 mg/kg Zn pollution respectively. Also, dehydrogenase activity (DHA) increased in all the treated soil samples, unlike in control samples, with Zn-polluted soil samples treated with a combination of poultry wastes and cow dung producing the highest change in DHA. The recorded number of leaves was highest in seedling grown on samples treated with cow dung, which recorded 13.3±0.9, 13.7±0.5 and 13.3±0.5 leaves per stand at Zn pollution levels of 32.75 mg/kg, 42.02 mg/kg and 52.55 mg/kg respectively. The highest concentration of total chlorophyll was found in seedling on samples treated using a consortium of cow dung and poultry wastes. Bioaccumulation of Zn was observed as roots>leaf>stem. Thus, these amendments produced varying effects on various parameters of polluted soil and corn seedlings. The overall positive result observed in this study resulting from a combination of one or more of the amendments (organic supplements or PGPRs) indicate their ability to annul or reduce stress due to Zn heavy metal pollution.