Dynamics of phosphorus content and the activity of phosphatase in forest soil in the sustained nitrogen compounds emissions zone

This paper summarizes research work on the seasonal and profile dynamics of phosphorus content and the activity of phosphatase in soil next to the nitrogen industry. The results are presented of the total phosphorus (TP) and available phosphorus (AP) content and the alkaline phosphatase (AlP) and acid phosphatase (AcP) against the basic physicochemical properties (clay, pH, total organic carbon, total nitrogen). Three soil profiles were sampled from Brunic Arenosols 0.8, 2.0, and 2.5 km away from the nitrogen plant. The control profile was taken from the Tuchola Forest. The soil was collected in both spring and autumn. The results showed that the total phosphorus content was higher in spring than in autumn (the value of index of changes in time TI < 0) contrary to available phosphorus (TI > 0) and in both seasons in surface soils, the lowest, in profile I. Both total and available phosphorus decreased with depth along the soil profiles. The distribution index (DI) calculated for total phosphorus in surface soils demonstrated a rather moderate accumulation, while DI value for available phosphorus for profile III, a considerable accumulation. The availability factor (AF) for all the soil samples was above the threshold of phosphorus load (2%) in the two seasons in this study (from 2.00 to 10.13% for spring and from 3.92 to 21.19% for autumn), suggesting that the transformation rate from TP to AP was high, and AP supply for plant growth was sufficient. The correlation analysis showed a significant and positive correlation of available phosphorus with soil properties such as total organic carbon (r = 0.577), total nitrogen (r = 0.512), and clay (r = 0.493); however, there was no correlation with the activity of phosphatases.