Over 2004Over -2006, effects of mineral fertilisers (60 N + 30 P + 60 K kg/ha or 120 N + 30 P + 60 K kg/ha) and farmyard manure (12 or 24 t/ha) application on biological and chemical properties of soil were studied in seminatural grassland. The research trial was established at Radvaň site, central Slovakia (altitude 480 m, loamy to sandy-loamy Cambisol). These parameters were investigated during the growing seasons: CO 2 production, intensity of total N mineralisation (TMN), the rate of nitrification (NIT), total C content in microbial biomass (MB-C), C ox , N t , P, K, Mg and the humic acids to fulvic acids ratio (HA:FA). At the application of mineral fertilisers, the highest N rate significantly increased TMN and NIT, mainly in 2004 and 2005. The manure application showed the strongest effects on the biological parameters. The manure rate of 12 t/ha significantly increased the soil respiration in 2005 and 2006 as well as TMN and NIT throughout the research. The manure application increased also the soil pH, MB-C, N t , Mg, P and C ox .