**2.2 Soil quality indicators**

In Canada and Brazil as well as in other countries, soil mismanagement led to soil degradation [30, 31]. There is a great challenge to address soil problems and optimize resource-use efficiency to sustain soil productivity [32]. Soil quality impacts nutrient supply and resistance to erosion [33, 34]. Keppel and Kreft [4] provided a list of biological, chemical and physical indicators of soil quality measurable at various scales of agroecosystems (**Table 3**). Biological indicators are presently the least documented but technologies of metagenomics will fill this gap in years to come [35]. Point-scale indicators can be integrated into maps to guide precision agriculture at field or subfield level. It is still difficult to evaluate soil quality uniformly among stakeholders with respect to soil threats, soil multifunctionality and ecosystem services [36].


**Table 3.**

*Indicators of soil quality [4, 35].*
