Comparative Assessment of Sweet (Zeamays Convar.Saccarata) and Dent Maize (Zeamays) for Phytoremediation of Chromium and Nickel Polluted Agricultural Soils

Abstract

The consequential effects of heavy metal consumption by man suggest the need for plant assessment for bio-concentration and translocation potentials. This study aimed at comparing the potential of dent maize with sweet maize for phytoremediation of Chromium (Cr) and Nickel (Ni) contaminated soils. Soil samples were taken randomly to a depth of 20 cm. Out of the samples taken; about 500 g of the samples were homogenized, dried, sieved, and used for the determination of soil physicochemical properties. The remaining soil samples were used to fill the polythene bags for the plant growth. The experimental design used was 22 by 2 general factorial design consisting of 4 treatments (1 g/dm3 of Ni (NO3)2.6H2O; 3 g/dm3 of Ni (NO3)2.6H2O; 1 g/dm3 of Cr (NO3)2.9H2O and 3 g/dm3 of Cr (NO3)2.9H2O), 2 replicates of each and the control. The setup was made for each of the maize types. Three seeds of maize were planted on each of the soil samples at a depth of 4 cm and the setup was properly monitored. Soil samples were analyzed at day 1 and every 14 days interval in a period of 70 days after planting (DAP). The result of the initial analysis of the soil samples indicates that the control soil sample contained 0.17+0.002 mg/kg of Cr and 0.03+0.001 mg/kg of Ni for soil seeded with both the dent and sweet maize. The mean concentration of Cr and Ni from the soil samples taken from soil contaminated with 1g treatment were 1.24+0.001 mg/kg and 1.43+0.002 mg/kg respectively, while that contaminated with 3g treatment has 3.98+0.02 mg/kg of Cr and 2.96+0.02 mg/kg of Ni. The results also show a reduction in the heavy metal concentrations of the soil through the 70 days of planting. The Cr and Ni contents of the two maize types increase with the increase in the amount of metals (3 g > 1 g> control) in the soils in which they were seeded. Though, the two types of maize are good phytoplant, sweet maize is more active in Cr removal than dent maize. The two maize types are better in bioaccumulation than in translocation. The growth of the plants was not retarded by the presence of the metal which shows their tolerance and effectiveness in remediating Cr and Ni contaminated soil. The use of this technology will help in attaining sustainable development goals as it addresses the problem of environmental degradation while the subsistence agriculture will be promoted and hence poverty will also be alleviated or eradicated.