Asian Journal of Plant and Soil Sciences

The wastes from cassava processing mills are usually discharged uncontrollably into the environment where they cause serious environmental challenges. This research work was undertaken to investigate the effects of the cassava mill effluent on the physicochemical effects and also to determine the effects of the polluted soil on the growth of maize plants. Fresh cassava mill effluent and unpolluted soil samples were collected and analyzed physicochemically. The soil sample was polluted with the cassava mill effluent and the polluted soil was also subjected to physicochemical analysis after 31days. Germination and growth of maize plants were also investigated using soil samples polluted with different concentrations of the cassava mill effluent. The results of the physicochemical analysis showed that the effluent was acidic (pH 3.95). It has total titrable acid value of 139mg/l, total dissolved solid value of 654.86mg/l, nitrate and cyanide contents of 89.65mg/l and 32.78mg/kg respectively. The concentration profile of metals was in the order Ca>K>Mg>Na>P>Zn>Pb>Fe>Cu>Mn. The results of the analyses of the unpolluted soil and the effluent polluted soil samples showed that the effluent had noticeable effects on the physicochemical properties of the soil. The effluent increased the acidity of the soil from pH 6.85 to pH 4.25. Statistical analysis of the results obtained from the physicochemical analysis of the polluted and unpolluted soil showed that there is a significant difference in the physicochemical characteristics of the unpolluted and polluted soil samples. The polluted soil also, at higher concentrations of the effluent  inhibited the germination of plant. Irrigation of healthy growing plants with 100% concentration of the effluent resulted to the withering of the plants after few days. Elemental analysis of the healthy and withered plants showed a remarkable increase in the concentrations of metals in the withered plants. The effect of the effluent on the growth of plants was due to the presence of cyanide which makes the effluent acidic. This acidity affects the germination and growth of plants. This research work revealed the fact that the effluents from cassava processing mills have significant effects on the physicochemical properties of the surrounding soils and also affected the growth of plants on these soils negatively. It therefore suggested that this effluent should be treated properly before disposal to the environment.