One of the ways to improve the production properties of replanted soil is to use soil fertilisers containing humic acids. The aim of the study was to analyse the impact of a natural soil activator H-850 WG, containing about 60% of humic acids, on some physical and chemical properties of soil and its enzymatic and respiratory activity in replanting conditions. The research was carried out in 2015-2017, on two kinds of soil: replanted soil from an orchard where apple trees had been cultivated since 1949, and the so-called crop rotation soil from an orchard where apple trees had not been cultivated for 10 years. Replanted soil compared to crop rotation soil had a lower enzymatic and respiratory activity, higher salinity and a lower content of some macronutrients. Two variants were set up at both research sites, i.e. control, without any treatment, and a trial, where the soil was sprayed with the preparation H-850 WG, containing humic acids. The results of this three-years experiment indicate a positive effect of humic acids on some physico-chemical properties of soil. The soil pH, soil nutrient content, as well as the level of its respiratory and enzymatic activity increased. The previous soil use had an impact on how efficiently the humic acids were used. Particularly evident effects occurred in replanted soil. An increase in this soil’s enzymatic and respiratory activity after the application of humic acids was much higher than in crop rotation one. Both the activity of two soil enzymes, dehydrogenases and proteases, and soil respiratory activity were positively correlated with soil acidity and the soil content of N, P, Mg and Ca. A significant negative relationship was found between soil salinity and its biological activity.

25.3.2020