In the sixth agroecological region of the brown forest soils from the agroecological map developed by the Institute of Soil Science, Agrotechnology, and Plant Protection "Nikola Pushkarov," and presented by Assoc. Prof. Ivanka Lyubenova during a webinar of the National Science and Innovation Council, seven sub-regions are included, which entirely cover the mountainous area of the brown forest soils and primarily pertain to the forest land fund of the country. These are the Petrohan, Sredno Staroplaninski, Tran-Osogovski, Ograzhdenski, Samokov-Srednogorsky, Rila-Planinski, and Rhodope regions.
The main soil cover consists of brown forest soils. This soil type is widespread in all mid-mountain areas of the country at altitudes of 750-900 m to 1500 m above sea level. The arable land in these regions occupies a relatively small area, and mainly in the lower mountain parts. Here, the climatic conditions are unfavorable for the main agricultural crops, but notably good for growing potatoes, as well as for meadows and pastures.