This study examined how land-use types affect the stocks and depthwise distribution dynamics of organic carbon (Corg), total nitrogen (Ntotal), and plant-available potassium (K) and phosphorus (P) within the 1-m soil profile across soils of different genesis. We conducted the research from 2019 to 2022 in the middle taiga subzone of Karelia (Eastern Fennoscandia). The study sites included arable land, hayfields, forests of natural regeneration on former agricultural lands aged 15–20 and 65–75 years, and reference forests aged 100 years and older, developed on texturally differentiated, alfehumus, organo-accumulative, and ferruginous metamorphic soils. Both land-use type and soil genesis influenced biogenic element stocks and their vertical distribution. The changes affected not only surface horizons but also deeper soil layers. Agricultural use led to statistically significant accumulation of biogenic element stocks. On average, arable soils accumulated 193.8 t/ha of Corg, 16.8 t/ha of Ntotal, 1.96 t/ha of plant-available potassium, and 2.54 t/ha of plant-available phosphorus. In forest ecosystems, biogenic element stocks tended to decline. Soils under mature forests contained, on average, 83.4 t/ha of Corg, 6.0 t/ha of Ntotal, 0.24 t/ha of plant-available potassium, and 0.65 t/ha of plant-available phosphorus. In forests, carbon accumulated primarily in the upper profile, especially in the forest floor, and declined sharply with depth. Nitrogen also accumulated in surface layers, with maximum values observed in arable land, hayfields, and young forests. Arable land and hayfields showed a relatively uniform depth distribution of carbon and nitrogen. In forest ecosystems, potassium and phosphorus displayed predominantly accumulative–eluvial–illuvial or weakly differentiated distribution patterns, whereas agricultural lands showed preferential accumulation in the middle part of the soil profile.
I. A. Dubrovina (Mon,) studied this question.