**6. Soil quality**

Soil quality (SQ ) stands out regarding the sustainable development of the global biosphere due to the fact that it is one of the most important terrestrial ecosystem functions. SQ is an indicator as a comprehensive reflection of the soil physically, chemically, and biologically. Revealing the dynamics of soil conditions, this sensitive indicator may change with the effect of different land uses and ecological restoration measurements [99–101]. Changes in land use have an impact on the physical and chemical properties of the soil, biological processes, and land productivity, ultimately leading to a change in SQ (**Figure 1**) [102, 103]. The impacts of the factors and their interaction on the soil quality were visualized in **Figure 1**.

In recent years, intensive efforts have been made on the concept of SQ and a reliable method to be used in measuring SQ. Some researchers define soil quality as the soil's capacity and suitability for use based on its functions. Capacity is defined as a common function of properties including climate, topography, vegetation, and parent material while suitability is associated with land use and management as a dynamic concept influenced by humans. However, it is known that there are some losses in the physical, chemical, and biological properties of the soil affected by land use and land management measures worldwide [104, 105]. In summary, SQ is how well the soil promotes and enhances plant and animal productivity and maintains or improves water and air quality. Maintaining and promoting SQ, ensuring ecosystem sustainability, and making rational management plans are fundamental requirements [106]. Accordingly, the welfare of a society largely depends on the productivity power of the land and the sustainable use of this power. In the opposite case when these soil conditions are not considered, it is inevitable that the land degradation will continue and it will lose its functionality within the ecosystem as a result of the disruption of its productivity and fertility parameters, as in other natural resources.
