This study examined the effect of fertilisation with compost prepared from hygienised sludge with an addition of pine-tree bark and mulching with fresh forest ectohumus on selected growth parameters in two- and three-year seedlings of common beech and the occurrence of mites (Acari) in soil. The experiment was carried out in 2009-2010 in the Białe Błota forest nursery (Bydgoszcz Forest District) on proper rusty soil. The entire area of the experiment was irrigated with a stationary sprinkler. The beech seedlings on the plots where compost had been used as fertiliser were significantly taller than those growing on the plots where mineral fertilisers had been applied. Mulching increased the height of the seedlings significantly only in the last, third year of the study. The tallest three-year-old seedlings were found on the plots in which both of the tested procedures had been carried out. Neither of the factors under study had a significant effect on the diameter of the root neck in the second year of the nursery cultivation, but they increased it significantly in the third year. Fertilisation with compost with an addition of pine-tree bark increased the number of leaves per plant and the leaf area in two- and three-year-old seedlings. A beneficial and significant effect of mulching on these parameters was found in the third year of cultivation. A significantly positive effect of mulching on the mite gathering density was recorded in the second year of the nursery cultivation. However, both of the experimental factors had a positive effect on the occurrence of those arthropods in the third year of the study. Oribatid mites were the most numerous mite order and they were found in the greatest density on plots where mulching had been applied. Fertilisation and mulching increased the Oribatida/Actinedida ratio, which may indicate an improvement of the biological balance in the soil environment.