SEASONAL CHANGES OF N-NH4

The paper presents seasonal changes in the concentrations of ammonia, nitrate and phosphate ions in podzolic soils under the Vaccinio uliginosi–Betuletum pubescentis and Empetro nigri-Pinetum plant communities. It results from the conducted investigations that the distribution and accumula-tion of mineral forms of nitrogen and phosphorus are considerably affected by atmospheric condi-tions such as temperature, humidity and precipitation. Analysed soils were characterised by a strongly acid reaction, which decreases with the depth of the soil profiles. A statistically significant correla-tion was found between the content of biogenic substances in soil and litterfall. The highest con-centration of biogenic substances was observed in spring and summer months. Among analysed ions the ammonia form predominated, which mean content remained within the range from 0.12 to 6.69 mg/100 g d.m. Concentration of nitrates ranged from 0.05 to 0.13 mg/100 g d.m., while that of phosphates – from 0.04 to 3.09 mg/100 g d.m. The predominance of the ammonia and phos-phate forms over the nitrate form in the organic horizons may result from their retention by the sorption complex. Nitrate ions exhibit greater mobility and are leached deeper into the analysed soil profiles