The objective of the study was to compare the impact of three systems of multiannual fertilization applied in two long-term field experiments on the content of phenolic compounds in the soil. In the study, both natural (manure, slurry) and mineral (NPK) fertilizers were used, along with combined, organic-and-mineral fertilization. Experiment I was established in 1972 on grey brown podzolic soil; experiment II, in 1973 on brown soil. In both experiments crops were cultivated in a 7-year rotation, with a 75% share of cereals. The experimental samples were taken from the top layer of soil after 36 (experiment I) and 35 (experiment II) years following the establishment of the experiments. It was demonstrated that the presence of phenolic compounds in the soils was significantly dependent on the contents of organic C and total N, type of soil and the type and dose of used fertilizers. In grey brown podzolic soil, the content of total phenolic compounds was at a lower level than the content found in brown soil. Multiannual fertilization contributed to an increase in the content of total phenolic compounds in relation to the values obtained in control objects, which was particularly reflected in the soil originating from objects fertilized with slurry applied at a dose being equivalent to manure in terms of the amount of introduced organic carbon. The percentage of water-soluble phenols in the total content of these compounds in grey brown podzolic soil was at the level of 18.4%, while in brown soil it amounted to 29.1%.
Annual and interannual phenomena and canopy behavior of prickly comfrey (Symphytum asperum Lep.) were studied in a 10-year experiment with 25 measurement sessions during the growing season. The results confirm the importance of long-term experiments in studying plant phenomena, biometrics and behavior. Prickly comfrey produced a green canopy each year and growth started very early in spring. Maximum plant height was less than 160 cm. Annual phenomena (growth initiation, seedling phase, flower phase, seed phase, senescent phase), interannual phenomena (initiation and youth, reproduction, new generation formation, plant death) and two population cycles (colonization and expansion) were measured. The duration of annual development up to canopy death can be expressed as x+2x+3x+2x, where x is initial growth. The genetic structure and activity of prickly comfrey promotes generative development of the species. Its age can be measured over a single and several vegetation generations. The ability to change the angle of vertical stem growth after 9 weeks can be considered a functional behavior of prickly comfrey and part of its life strategy. The differences between the organs in the upper and lower parts are very considerable and should be taken into account in morphological descriptions of this species. The upper and lower stems and leaves showed differential growth. Both stem and leaves were densely setose. Old leaves were 3.8 times longer, 4 times broader and 2.4 times thicker than young leaves. Hairs were on average 3 times longer on old than on young leaves. Flowers had contact with pollinators making relatively long visits to them.