Tillage in long time no-tilled fields.

Researchers in Nebraska looked at whether or not long term no-tilled fields were harmed by tillage.  Sometimes tillage is the most economical way to control certain perennials or to reduce stratification of nutrients, especially phosphorous.  They found that over a five year period, soil properties were not changed very much by tilling once as opposed to not tilling.  The only property that was affected negatively was the soil microbial community.  Also, they found that in the time period studied, that nutrients became stratified again.  I saw nothing in the study that convinced me that a one time tillage operation would be particularly beneficial to a committed long term no-tiller.