Joe,

I started dabbling with grid soil samples in the mid-late 90's. I was seeing a lot of low Ph's as we had not kept up with our lime applications for years. Also in the late 90's Kyle Smith of Beck's Hybrids started his high cal lime plot where he dumped on 10 (?) tons of high cal lime (among other limes & rates). His plots kept showing a marked yield increase to the high calcium vs the mag lime....both in corn & beans.

Here is one sheet of info after a quick search....
http://www.beckshybrids.com/research/2002/pg62.pdf  There is much more information than that, so I would do some more searching on their PFR study archives to glean more data.

http://www.beckshybrids.com/research/2003/pg40.pdf

Also.....my soil tests were almost all high in mag....with base% in the 20-30% ranges. Kyle preached a 7-11% mg sat, and calcium in the 70-80%.

So in 1999 I purchased a lime spreader & spread 1500 tons of high cal (from Swayzee) during that winter. Since that time I cannot give you any hard evidence of yield bumps. I did not have a yield monitor, or weigh wagon to quantify anything. However, I noticed right away that many areas of visible nutrient deficiencies in the plant were disappearing. And this was verified in my subsequent soil samples. The nutrient levels evened out into a very small range (soil was now tested in grid zones by soil type). Even with my High Ph's I have not had to spray foliar manganese on my beans for 10+ years.

I have caught flak for having Ph's in the 7.0+ range.....but I do not lime for Ph as much any more. I lime to keep my Cal % in the 70-80 range.....and that just happens to result in a 7.0-7.3 ph range for my soils.

The past couple of years now I have found the need to spread both High cal and mag lime in the same fields depending on site, as my Mag levels have come down, and I have found a couple areas of low Mg in my tissue samples.

In hind sight, I really wish I would have kept a small plot where I could check myself.  I'm not going to tell anyone who does not do this that they are wrong. But I do believe I have made money on this farm by following the high cal program.

And without any hard yield data.....I can use my soil tests, tissue samples, and visual crop appearance to prove it to myself at least.