Influence of Fly Ash as a Soil Conditioner on the Growth and Yield Performance of Napier Grass (Pennisetum purpureum)

Abstract

Fly ash can enhance soil structure, nutrient availability, and water retention, making it a promising soil conditioner for agricultural applications. The growth and yield performance of Napier grass (Pennisetum purpureum) cultivar Pak Chong 1 was evaluated under different soil treatments. The control treatment consisted of 313 kg/ha NPK (Nitrogen, Phosphorus, and Potassium), 1,563 kg/ha dolomite, and 6,250 kg/ha manure, while fly ash was applied at levels of 1,563, 3,125, 6,250, and 12,500 kg/ha. Growth parameters such as plant height, number of tillers per clump, leaf-to-stem ratio, dry-to-fresh weight ratio, and heavy metal accumulation were examined. The fly ash significantly increased plant height, tiller number, and biomass yield compared to the control in most cutting cycles. However, the control occasionally exhibited higher leaf-to-stem ratios, suggesting that fly ash promotes stem growth more than leaf expansion, indicating an advantage for biomass production. Notably, the 3,125 kg/ha fly ash treatment resulted in considerable lead accumulation in leaves; however, this Pb originated from the native soil, not the fly ash, which had non-detectable levels. Higher fly ash levels (e.g., 12,500 kg/ha) effectively reduced Pb uptake, indicating the need for dosage optimization to ensure heavy metal immobilization.