Applied Tropical Agriculture Volume 29, No. 1, 16-23, 2024. © A publication of the School of Agriculture and Agricultural Technology, The Federal University of Technology, Akure, Nigeria. ----- Assessment of Nutrients Mineralization in Degraded Soil Amended With Coal Ilori, A. O. A.*, Shittu, O. S., Akande, T. Y., Amoloja, O., Ajayi, S, O., Ilo, S. A., Akindahunsi, A. O. and Saleeman, S. O. 8Department of Soil Science and Land Resources Management, Federal University Oye-Ekiti, Ekiti-State, Nigeria *Corresponding author: augustus.ilori@fuoye.edu.ng ABSTRACT Poor management practices degrade agricultural lands. Composite sample taken at a depth of 0-30 cm from degraded soil in Federal University Oye-Ekiti, Nigeria was amended with coal in an incubation study. One kg potted soil replicated thrice were amended with coal at the rate of 0, 5, 10, 15 and 20 ton ha -1 and arranged in a complete randomized design (CRD). Scooped samples at 3, 14, 28, 42 and 56 days of incubation were analysed for selected chemical properties. The pH decreased significantly with the days of incubation while other soil properties increased except for available phosphorus, total nitrogen, sodium, exchangeable aluminum and cation exchange capacity, having irregular trends. For amendment rates, 0 ton ha -1 recorded a significantly higher pH of 4.69 while rate 20 ton ha -1 had the highest but nonsignificant organic carbon (OC, 17.43 g kg -1 ) but other soil parameters were statistically the same. Incubation days correlated significantly with all parameters except the available phosphorus, while coal rates were generally non-significantly correlated. Generally, nutrients mineralization increased with days of incubation but exhibited an irregular pattern with coal amendment rates. Therefore, 15-ton ha -1 coal is suggested for the improvement of degraded soils as the rate was not significantly different from the higher amendment rate. Keywords: amendment, coal, degraded soil, incubation days, mineralization, nutrients. INTRODUCTION Agricultural lands have been degraded by the continuous usage and poor management practices by rural farmers, which have generally affected soil health and productivity in terms of nutrients supply for crop production and soil biodiversity. Degraded soils are usually with undesirable changes brought about by human activities interacting with natural phenomenon (Zia-ur-Rehman et al., 2016) and it’s one of the serious prevailing issues in our modern era, adversely affecting soil’s natural fertility in order to enhance our economic values along with ecological issues. Soil degradation refers to the physical, chemical and biological deterioration in soil quality involving among others the decline in soil fertility due to loss of organic matter, structural degradation resultant from erosion, adverse changes in salinity, acidity or alkalinity, and the effects of toxic chemicals, pollutants or excessive flooding. According to Lal (2015), degraded soil is characterized by decline in quality and decrease in ecosystem goods and services which is a major constraint to achieving the required optimum agricultural production. More so, the use of coal in energy sector is gradually declining globally due to its negative adverse effects on the climate and environment. However, Nigeria still holds large coal reserves, standing at an estimated 2.8 billion metric tons across 17 fields (Vanguard, 2017). It is against this backdrop that coal is being studied to evaluate its effects on soil health and potential productivity when being used alternatively and sustainably as a soil amendment material. Coal formation occurred when dead plant matters decay into peat and deep buried over millions of years under heat and pressurized conditions and got converted into coal (US-EIA, 2021). Coal is mostly carbon, with variable amounts of major elements such as hydrogen, sulfur, oxygen, and nitrogen, each constituting more than 1% of the coal by weight, (Swaine, 2013). More so, coals particularly low rank coal (LRC) is a great source of humic substances (Gianoulli et al., 2009; Janos et al., 2011). Soil conditioners are products that are used to improve poor soils, and/or to rebuild soils which have been damaged by improper management practices, making poor soils more usable and maintaining soils at peak conditions (Noble, 2011) such as building soil organic matter (SOM) which aims to restore soils’ chemical, physical, biological and ecological functionality (Amoah-Antwi et al., 2020). Various forms of coal and its by-product has been used as 16