## 4 Discussion  
### Grasslands vs. Arable Land: Carbon Sequestration Potential  
Our findings on the greater SOC sequestration potential of grasslands compared to arable land are consistent with those of other studies [30; 31; 32]. According to [33], converting forests or grasslands into arable land leads to a significant reduction in SOC, while converting forests into grasslands does not have the same impact. Both natural and artificial grasslands, as well as forests, are more effective in carbon storage than arable land [3]. Within the study area, the primary reason that grasslands store organic carbon more effectively than arable land is likely due to the differences in tillage practices. Grasslands benefit from the absence of tillage, which enhances soil's aggregate stability and creates favourable conditions for organic carbon storage [34; 35]. Although ploughing facilitates root growth by allowing for water and oxygen infiltration, it is also a major factor in soil erosion and structural degradation [36]. According to [37], no-tillage methods in arable lands have been shown to retain carbon in the soil and reduce carbon emissions to the atmosphere. In addition, no-tillage practices support soil microbiota and improve soil's water-holding capacity. Another critical factor influencing carbon storage across different land use types is the source and quantity of organic matter [38; 39]. For instance, plant residues and root exudates in grasslands provide a continuous supply of organic inputs, which may enhance soil's microbial activity and support SOC stabilization [40]. Conversely, arable lands, typically disturbed by tillage, exhibit lower root biomasses and, consequently, a reduced capacity for organic carbon accumulation [41]. The lower carbon stock values observed in certain grassland sampling points (Figure 6) may be attributed to overgrazing, which reduces the biodiversity and, subsequently, SOC content [42]. Additionally, uncontrolled and intensive grazing likely contributed to soil compaction in these areas, further reducing SOC levels [5]. In contrast, grasslands that were less affected by grazing, where the plant biodiversity was higher, demonstrated the greatest carbon stock values. These regions exhibited more abundant root biomasses and stable soil structures, both of which led to increased SOC levels. In arable lands, the lowest carbon stock values were recorded in areas with corn and forage crops, while higher carbon stock was associated with intermediate crops or arable lands fertilized with organic materials. Figure 7: Spatial distribution of carbon stocks in relation to soil class (CER—Cernisoil, HID—Hidrisoil, LUV—Luvisoil). These results, in line with [11; 43], underscore that land use and agricultural management practices significantly influence SOC stocks in agricultural landscapes. To capitalize on the carbon sequestration potential of high-nature-value grasslands, it is essential that land management practices are supported by both scientific evidence and policy frameworks. This reinforces the need for targeted policies that encourage sustainable land use practices, particularly in agricultural contexts. For arable lands, no-tillage or minimum-tillage methods--which are supported by policy frameworks such as the Common Agricultural Policy (CAP) and initiatives like the Carbon Farming Initiative (CFI)--have shown promise in enhancing SOC stocks while reducing carbon emissions [37]. In addition, our results suggest that implementing practices such as organic fertilization, crop rotation, and agroforestry can further enhance carbon storage in agricultural soils. Such approaches should be actively promoted through agricultural policy and accompanied by financial incentives to ensure both economic and environmental sustainability. That said, despite the benefits, the adoption of no-tillage or minimum-tillage methods may face resistance due to the challenge of shifting farmers' traditional mindsets, even with existing CAP financial incentives [44].