"Cutting fertilizer" always has to start with the question of "cut from what".

Obviously we should not cut below the crop removal rate. The problem is determining just what that removal rate is - and it will vary enormously due to many factors.

When most folks talk about reducing fertilizer rates with strip till or "banding" application methods (Dr George Rehm at the U of MN has done alot of research on this), they are USUALLY referring to results that indicate by indexing the fertilizer to the plant location you can usually reduce rates from the older, standard, land-grant university soil-test based fertilizer recommendations.

The implication is that these older, usually dry surface broadcast-based recommendations that usually come back with soil test results were applying MORE than the plant removal rates in most cases.

"Cutting" fertilizer rates by say 1/3 from these older, university soil test based recommendations may have little to do with plant removal rates and may usually be done without "mining" the soil.

In my opinion THAT is usually the reference base for suggestions that strip till, banding or other indexed applicatrion system may often permit significant reductions in fertilizer rates. That is my understanding also. This is also what I have seen at multi-year strip till farms. 

What should also be stressed in these "reduced rate" fertilizer discussions is the necessity to apply the fertilizer you do apply as uniformly, row to row and along the row, as possible.  Some folks who go to a say 1/3 reduced rate and then have uneven crops blame the rate reduction when in fact their application system was putting out VASTLY different rates from row to row. This non uniformity is masked when we are applying excess fertilizer.

When fertilizer is cheap then maybe it was not worth taking the time, effort and making the investment necessary to do this right. When fertilizer is high priced, looking into setting up to apply 1/3 less than previous soil test recommendations with on-planter application or strip till may make economic sense. 

I always suggest to folks to not take anyone's word for it but try a test field on your own farm before making across the board changes. jmho.

Jim at Dawn