Effect of Coal Ash Enriched Compost on Soil Chemical Properties of Ultisols

Abstract

Ultisols are soils that develop in humid tropical areas and are formed due to an intensive leaching process, resulting in the accumulation of clay in the subsoil. A decrease in the chemical-physical properties of Ultisols, such as a decrease in the levels of organic C, total N, cation exchange capacity (CEC), base saturation, and on the other hand, an increase in Al saturation and soil bulk density, can occur as a result of continuous monoculture cultivation. Improving the quality of degraded soil is usually carried out by amelioration using compost. Still, the addition of compost often only has a significant effect on improving the physical properties of the soil. Coal ash in the form of fly ash-bottom ash (FABA) is a waste product from burning coal in electric steam power plants. The amount of FABA is very abundant and its utilization is minimal. FABA has an alkaline pH and contains various nutrients in varying amounts. Therefore FABA has the potential to be used as an ameliorant to improve the chemical properties of acid soils such as Ultisols. Experiments with the spread technique of compost+FABA at a dose of 50 tons/ha and in rows technique at a dose of 25 tons/ha, 15 tons/ha, and 5 tons/ha were conducted to determine the effect of the treatment on soil chemical properties. Application of FABA-enriched compost in rows technique at a dose of 25 tons/ha had a significant effect and showed the best soil chemical properties, including increasing organic C, total N, total P, available P, exch-K, -Ca, -Mg, and -Na, CEC, base saturation, and decreased Al saturation. Utilization of FABA as a soil ameliorant combined with compost can improve soil quality more effectively.