N/P/K Leaching of Sweet Corn in Growing Media Controlled with the Coal Combustion Products Fly Ash and Bottom Ash

Fly ash and bottom ash, or coal combustion products (CCP), are wastes from coal-fired boilers of electricity power plants. CCP were evaluated as a soil amendment and partial fertilizer substitute in a short-term pot experiment and showed potential to influence growing media properties under controlled conditions. However, these findings are limited to the early growth stage and pot-scale conditions, and further studies under field conditions through harvest are required to confirm their effects on plant growth. The study examined the leaching of N/P/K from sweet corn growing media enriched with different CCP proportions. Latosol soil was incorporated with 0%, 25%, 50%, 75%, and 100% CCP (m/m) to support sweet corn seedlings in a pot experiment. N, P, and K leaching from the growing media was evaluated. The results showed that sweet corn growth was restricted in CCP-amended media. Increasing CCP proportion markedly reduced plant growth, with decreases of up to 57.00% in seed emergence, 59.56% in plant height, 42.50% in leaf number, 70.59% in dry weight, and 38.00% in root number compared to 100% soil; however, the 25% CCP treatment increased root volume. Increasing the CCP proportion also increased N and K leaching and leachate pH; conversely, P leaching was lower than in 100% soil. Since there were no toxicity symptoms in sweet corn, CCP could be used as a soil amendment and a potential source of NPK, with precautions to prevent nutrient leaching.