Abstract
The present study investigated the effects of hydrocarbon pollution on the growth and yield performances of okra after substrate amendment. Uniform weights (10 kg) of top soil were measured into buckets and thoroughly mixed with waste engine oil (WEO) to obtain uniform concentrations of 5 % w/w. Oil-polluted soils were amended with 100 g of any of poultry waste (PW), sawdust (SD), nutrient-rich sludge (NS), or a combination of the amendments in equal proportions at the rate of 1 % w/w. Healthy seeds were sown in amended and control soils on a weekly basis to follow up on time of plant growth response and survival. Results showed that performance of crop was retarded by the contaminant; the first growth of okra was observed when seeds were sown 28 days after pollution (DAP) in the PW-amended soil. However, the seedlings died within 11 days. Okra plants grew up till maturity only when they were sown at 56 DAP in the amended soils and 70 DAP in the unamended soil. Okra plants in the PW-amended soils showed better crop yield in terms of mean pod dry weight (1.241 g), mean number of seeds/pod (12.25), and 100 seed weight (5.24 g), compared to all other plants in oil-polluted soils. The study thus demonstrates that for 5 % w/w oil-polluted soil, the earliest time for sowing okra is 70 DAP when soil was unamended (p<0.05), and best at 56 DAP in poultry waste-amended oil-polluted soil.
Key Words: Amendment, Okra, Plant survival, Pollution, Soil
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