​Effect of Palm Oil Mill Effluent on the Growth of Maize (Zea mays)

Abstract

Background: Raw palm oil mill effluent is toxic effluent capable of posing serious threat to plants when discharged to the environment. In developing countries, the untreated effluent is often discharged to the surrounding land due to high cost associated with its treatment. The aim of the current study was to evaluate the impact of palm oil mill effluent treated with locally available material on the growth of maize. Methods: The bunch ash obtained from local material by burning de-fruited oil palm bunch was used for the treatment. The experiment was consisted of eight treatments of concentrations of palm oil mill effluent viz 1.0%, 2.0%, 3.0%, 4.0%, 5.0%, 6.0%, 7.0% and 8.0%. The treatment was carried out on potted maize plants with six replications. Four kilograms of soil was weighed into each pot. Six pots were labelled as control, with untreated palm oil mill effluent added to them. Eight other groups consisting of six pots each were treated with 1.0%, 2.0%, 3.0%, 4.0%, 5.0%, 6.0%, 7.0% and 8.0% concentrations of the effluent. The maize seeds were planted one in each pot to avoid overcrowding. The pots were transferred to greenhouse and each pot was moistened daily with the specified concentration of the palm oil mill effluent. The growth rate, plant height and leaf length of the maize plants were thereafter determined. Result: The 8.0% concentration of bunch ash in the effluent had the highest expected effect on all the parameters whereas the control gave the lowest expected effect. The effects increased as the concentration of bunch ash in the effluent increased, indicating that increased concentration of bunch ash recorded significant increase in growth rate, height and leaf length of maize. The analysis of variance for the obtained data showed that the effects of the different concentrations were significantly different. This study provides an alternative and cost effective method of ameliorating the toxicity of palm oil mill effluent to plants.