Management-sensitive soil health indicators in organic and conventional Quebec vegetable production systems

Vegetable cropping systems are intensively managed, yet soil health (SH) remains understudied. This study compared 50 organic and conventional vegetable farms in Quebec by documenting management practices, assessing 39 SH indicators, and identifying a minimal indicator set for routine monitoring. Soils were sampled at 0–10, 10–20 and 30–50 cm, with indicator-specific depths. Organic farms more frequently reported cover crops (100% vs. 45%), organic amendments (100% vs. 20%) and reduced tillage (56% vs. 10%), and had greater crop and cover-crop diversity. Management differences were strongest at 0–10 and 10–20 cm and less evident at 30–50 cm. Physical and chemical indicators showed few consistent differences; however, organic farms had 26% lower bulk density at 0–5 cm (0.89 vs. 1.20 g cm⁻³), 81% higher total C (3.48% vs. 1.92%) and 81% higher total N (0.29% vs. 0.16%) at 0–10 cm (all p<0.001). At 0–10 cm, microbial respiration, ACE protein and FDA hydrolytic activity were 1.67-, 2.22- and 2.62-fold higher, respectively (all p<0.001). Organic management was also associated with 27% higher fungal richness but 22% lower bacterial richness (Chao1; both p<0.001). Exploratory factor analysis identified two management-influenced SH traits: soil organic fertility and soil bacterial diversity/resource quality. The proposed minimal indicator set includes bulk density, total C and N, organic matter, microbial respiration, ACE protein, total bacterial abundance, Shannon diversity and Chao1 richness. These results identify management-sensitive SH indicators for vegetable systems and provide a basis for future validation against soil functions.