Zawartość i profilowe rozmieszczenie frakcji fosforu w uprawnych i leśnych czarnoziemach z poziomem cambic

Comparative studies on the content and profile distribution patterns of phosphorus fractions in arable and forest Cambic Chernozems were conducted near the village Báb (western Slovakia). Soil samples were collected from every 10 cm and analyzed using standard procedures in soil science. Long term differences in the type of the studied soils usage were reflected in their physical and chemical properties (bulk density, porosity, acidity, the total content of organic carbon and nitrogen), as well as in the content and profile distribution patterns of phosphorus fractions. Total phosphorus content ranged from 498.8 to 754.7 mg/kg in arable soil and from 480.4 to 835.9 mg/kg in forest soil. Residual fraction, which constituted 54.9−77.8% of total phosphorus in arable soil and 57.3−79.2% in forest soil, was a predominant fraction. Such large contribution of this fraction is typical for young soils, with weakly weathered mineral substrates. Exchangeable phosphorus in arable soil constituted 0.6−6.1%, while 0.5−3.0% in forest soil, showing decreasing trends with depth in both soils. Free iron oxides and carbonates were important factors influencing profile distribution of phosphorus in the investigated soils. Iron oxides bound the element mainly in acidified horizons, whereas carbonates in alakaline (Bw and C) horizons. Organic fraction significantly differed in the investigated soils. A much larger content and contribution of this fraction in total phosphorus was noticed in forest soil. The content of organic phosphorus was positively related to the content of organic carbon. Stable fraction of organic phosphorus predominated over labile one in both soils.