There are reports from ON showing both SOC increases, and not (more commonly the latter), with CC usage. The results from this 2024 survey of 500 farms (sampling to 30 cm) is very informative. On average, no CC effect. (Boundaries for categories of soil organic matter depend on soil texture.)

A good article about the confusing world of 'regenerative agriculture' and consumer interest.
www.foodnavigator-usa.com/Article/2025...

This is an outstanding review for those interested in using increases in soil organic matter to sequester carbon. Note especially this comment which describes a flaw common to many measurements of differences in SOM.

Interesting. A provincal survey of >500 farms in Ontario showed no effect of cover crops, or use of reduced tillage, on soil organic matter content. However, the presence of perennial forages in rotation, and use of pastures (the "no disturbance" tillage option), did increase SOM.

This is an excellent paper that I'd missed earlier. I've long been of the opinion that comparative crop productivity can explain much of comparative differences between no-till versus conventional (inversion) tillage in soil organic matter accumulation.
academia.edu/12012163/Car...