*Article* **Impact Assessment of the Long-Term Fallowed Land on Agricultural Soils and the Possibility of Their Return to Agriculture**

**Małgorzata Kozak \* and Rafał Pudełko**

Department of Bioeconomy and Systems Analysis, Institute of Soil Science and Plant Cultivation—State Research Institute (IUNG-PIB), 24-100 Puławy, Poland; rpudelko@iung.pulawy.pl **\*** Correspondence: mkozak@iung.pulawy.pl; Tel.: +48-81-47-86-769

**Abstract:** Agricultural land abandonment is a process observed in most European countries. In Poland and other countries of Central and Eastern Europe, it was initiated with the political transformation of the 1990s. Currently, in Poland, it concerns over 2 million ha of arable land. Such a large acreage constitutes a resource of land that can be directly restored to agricultural production or perform environmental functions. A new concept for management of fallow/abandoned areas is to start producing biomass for the bioeconomy purposes. Production of perennial crops, especially on poorer soils, requires an appropriate assessment of soil conditions. Therefore, it has become crucial to answer the question: What is the real impact of the fallowing process on soil, and is it possible to return it to production at all? For this purpose, on the selected fallowed land that met the marginality criteria defined under the project, physicochemical tests of soil properties were carried out, and subsequently, the results were compared with those of the neighboring agricultural land and with the soil valuation of the fallow land, which was conducted during its past agricultural use. The work was mainly aimed at analyzing the impact of long-term fallowing on soil pH, carbon sequestration and nutrient content, e.g., phosphorus and potassium. The result of the work is a positive assessment of the possibility of restoring fallowed land for agricultural production, including the production of biomass for non-agricultural purposes. Among the studied types of fallow plots, the fields where goldenrod (*Solidago L.*—invasive species) appeared were indicated as the areas most affected by soil degradation.

**Keywords:** unutilized agricultural areas (uUAA); abandoned areas; land use and land-use change; carbon sequestration; soil properties (physical and chemical)

**1. Introduction**
