dloc,

Thanks for posting the link.  However, I read that paper in a rather different light.  Looks to me like many studies find that removing surface residues does impact SOM long-term, especially under no-till.  (Tilled regimes tend to show less differences because SOM is being mined rather than maintained or increased.  Also, note that the authors are explicit about difficulties measuring SOM changes.) 

Further, surface residues are highly important for protecting soil aggregation from damage by raindrop impact.