Digging Deeper: Assessing Soil Quality in a Diversity of Conservation Agriculture Practices

Abstract. Conservation Agriculture (CA) aims to enhance soil quality through three main principles: minimizing mechanical soil disturbance, maximizing soil organic cover, and diversifying crop species. However, the diversity of practices within CA makes the effect on soil quality hardly predictable. In this study, an evaluation of soil quality in CA fields across Wallonia (Belgium) was conducted for four distinct CA-types. Three soil quality indicators were examined: the soil structural stability, the soil organic carbon:clay ratio (SOC:Clay), and the labile carbon fraction (POXC). Results revealed significant variations among CA-types. The CA-type characterized by substantial temporary grassland and tillage-extensive crops (e.g., cereals, meslin, rape, flax) in the crop sequence had the highest soil structural stability and SOC:Clay ratio. In contrast, the CA-type characterized by strict non-inversion tillage practices and frequent tillage-intensive crops (e.g., sugar beet, chicory, potatoes, carrots) had the lowest scores for the three indicators. Temporary grassland in the crop sequence appeared as the most influential factor improving soil quality. These findings highlight the need to consider the diversity of CA-type when evaluating the agronomic and environmental performance of CA systems, whose response depends on local soil and climatic conditions, the crops cultivated, and the specific combination of practices implemented.