The paper demonstrates seasonal changes in the content of organic carbon and phosphorus available to plants against the activity of phosphatases responsible for the transformations of that element in the soil caught by fire. The soil was sampled three times: April 2012, October 2012 and April 2013 from the surface horizon (0-15 cm) and subsurface horizon (15-30 cm), from four sites: from the site beyond the fire (control area), ecotone (border area) and from the soil burnt 150 m and 200 m away from the ecotone. The content of total organic carbon was the highest in the soil sampled 0-15 cm deep from the border area (ecotone) (16.77-23.11 g C kg^-1) as compared with the control and the area caught by fire. The highest available phosphorus content, irrespective of the sampling date, was recorded from the surface horizon 0-15 cm 200 m away from ecotone (74.08-85.02 mg P_E-R kg^-1) irrespective of the soil sampling date.

The activity of alkaline and acid phosphatase in the soil caught by fire was lower as compared with the control and ecotone in both horizons at all the research dates. There were reported significant negative values of the correlation between the content of available phosphorus in soil and the activity of alkaline (r = -0.599, p < 0.05) and acid phosphatase (r = -0.583, p < 0.05). The calculated factor of the changes in the activity of the enzymes investigated in time (TF > 1) showed that the process of soil regeneration was not completed a year after the fire. The calculated enzymatic index of soil pH (AlP/AcP) ranged from 0.35 to 0.77.

Keywords: burnt, phosphomonoesterases, physicochemical properties, soil