Long-term Mineral Fertilization and its Effect on Humic Condition of the Haplic Chernozems in Dobroudja

摘要

From the beginning of the 80s, studies are being carried out at the trial fields of the Dobroudja Agriculture Institute to determine the effect of systematic mineral fertilization at various types of crop rotation, and the effect of different tillage systems on the changes of humus content, humus reserves along the profile depth and the changes of its group and fraction composition [3, 4, 6]. The aim of this study was to characterize the changes in the humus content and reserves in soil, as well as the changes in its qualitative composition resulting from 30 year annual dressing with nitrogen, phosphorus and potassium in various norms and rates.