Enzyme activities and wheat growth response in soils amended with coal ash from the UK and Tanzania

Abstract

Due to the presence of essential plant nutrients and either acid or alkaline properties, coal ash can be a valuable amendment in improving characteristics and crop productivity of alkaline or acidic soils. This study aimed to evaluate the effects of coal ash application to woodland and arable soils on soil pH, selected soil enzyme activities (dehydrogenase, acid phosphatase, alkaline phosphatase, urease and β-glucosidase) and on vegetative growth of wheat. Two pot experiments were conducted in which wheat (Triticum aestivum var. Willow) was grown in woodland and arable soils amended with ash collected from either the UK or Tanzania, at concentrations of 0, 2, 4, 8 and 16% (w/w). Wheat was grown for 50 days. Soil amendment with UK ash at 0-16 % increased significantly (p<0.001) the pH of woodland and arable soils while amendment with Tanzanian ash at 0-16 % reduced the pH of both soils (p<0.001). Application of low concentrations (0-4%) of UK ash to both soils increased dehydrogenase and urease activities and wheat growth, but these ash concentrations didn’t show any significant effect on alkaline and acid phosphatase activities. Glucosidase activity increased significantly (p<0.001) when woodland soil was amended with 2% of UK ash, then decreased significantly with increasing ash concentration. Application of 16% UK ash also inhibited acid and alkaline phosphatase activities. Application of the Tanzanian ash at low concentration did not have any significant effect on the activities of enzymes studied while application at 8-16% inhibited all enzyme activities. Tanzanian ash did not affect wheat growth parameters when applied to both soils while UK ash improved wheat growth. This study demonstrates that soil amendment with coal ash can either cause beneficial or detrimental effects, depending on the nature of the ash and soil characteristics thus, strategic agronomic use of coal ash is recommended.