I’ve been doing a few small-scale tests of soil structure by simply seeing how easy it is for a fork to penetrate to full depth every six months or so. I started using no-dig in March 2014 and what I’ve found is that the longer a bed remains no dig, the easier I find the fork goes to full depth. In particular, growing potatoes has a massive benefit in that regard. The first season, I did fork along with hoeing away weeds before the first planting of beans and that worked well, but I did none of that the second season as the soil structure appeared good.
So I’m with Charles on this one. And I’m definitely seeing more and more worms as I harvest vegetables using the no-dig beds…….