Effects of the Application of a Mineral-and-Organic Fertiliser Produced from Brown Coal on the Occurrence and Infectious Potential of Entomopathogenic Fungi in Soil

This study compared the species composition and rate of entomopathogenic fungi occurrence in cultivable soil following the application of a mineral-and-organic fertiliser produced from brown coal. The material for testing consisted of soil samples collected in the second year of the experiment on two dates in 2015 (spring and autumn). The experiment was carried out on the following plots: control plot (no fertilisation); a plot fertilised with mineral fertilisers NPK presowing + N₆₀ for top dressing; a plot fertilised with NPK presowing + manure; a plot fertilised with a fertiliser produced from brown coal at a dose of 1 t/ha NPK presowing + N₂₀ for top dressing; and a plot fertilised with a fertiliser produced from brown coal at a dose of 5 t/ha NPK presowing + N₄₀ for top dressing. Entomopathogenic fungi were isolated from soil of particular fertilisation experiment plots using insect traps (Galleria mellonella larvae) as well as a selective medium. Three species of entomopathogenic fungi, i.e. Beauveria bassiana, Metarhizium anisopliae s.l. and Isaria fumosorosea, were isolated using two methods, from the soil samples collected from particular fertilisation experiment plots on two dates, i.e. spring and autumn. Fungus M. anisopliae s.l. proved to be the predominant species in the tested soil samples. The addition of the mineral-and-organic fertiliser, produced based on brown coal, to the soil at both applied doses contributed to an increase in the number of infectious units (CFUs) of entomopathogenic fungi formed in relation to the control plot.