Summary:

The aim of the study was to determine the influence of mulching and organic fertilization on the seedling vigour of Scots pine and occurrence of soil mites (Acari) in forest- and post-arable soils. Two different field experiments were carried out in the vegetation period of the year 2005 on light soils at two different sylvan-natural regions. The first trial was conducted at Białe Błota near Bydgoszcz – on a brown podzolic soil. The second experiment – at Lipnik near Stargard Szczeciński – on an acid brown soil. The experiments were run in a split-plot system with four replications. Two different factors were compared. The first row factor was fertilization, used in the two following treatments: N₁ – treated sewage sludge (⅔) + bark (⅓) and N₂ – treated sewage sludge (⅔) + sawdust (⅓). The second row factor was mulching, used in the two variants: C – without mulching (control) and S – mulching with litter. Scots pine seedlings grown on the forest soil at Białe Błota were characterized by increased height than those cultivated on the post-arable land at Lipnik. The best results, both on the forest soil as well as on the post-arable ground, were obtained in the case of treatment SN₁ (plots mulched with litter and fertilized with treated sewage sludge (⅔) with bark admixture (⅓)). The higher was the rainfall amount during the vegetation period, the lower was the seasonal irrigation rate supplied to the Scots pine seedlings. Because of this the seasonal irrigation water rate applied at Białe Błota was higher than that at Lipnik. Fresh mass of the above-ground parts of the Scots pine seedling was higher on the forest soil as compared to that on the post-arable land. The seedlings grown on the treatments mulched with litter were characterized by higher root mass in comparison to those on the control plots (without mulching). Mulching with litter influenced the general number of mites, the number of oribatid mites as well as their species diversity. Organic fertilization (treated sewage sludge with bark or with sawdust) did not influence these indices.